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| author | Mauro Carvalho Chehab <mchehab@redhat.com> | 2011-05-31 16:27:44 -0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@redhat.com> | 2011-07-27 17:52:05 -0300 |
| commit | 4266129964b8238526936d723de65b419d8069c6 (patch) | |
| tree | 38c6b5cd3dc99b8599391ffad3b87e399bef56a2 /Documentation/DocBook/v4l/compat.xml | |
| parent | 04893043ae9ea8aa82b712491ed25ba6c4ffbca3 (diff) | |
| download | op-kernel-dev-4266129964b8238526936d723de65b419d8069c6.zip op-kernel-dev-4266129964b8238526936d723de65b419d8069c6.tar.gz | |
[media] DocBook: Move all media docbook stuff into its own directory
This patch addresses several issues pointed by Randy Dunlap
<rdunlap@xenotime.net> at changeset ece722c:
- In the generated index.html file, "media" is listed first, but it
should be listed in alphabetical order, not first.
- The generated files are (hidden) in .tmpmedia/
- The link from the top-level index.html file to "media" is to
media/index.html, but the file is actually in .tmpmedia/media/index.html
- Please build docs with and without using "O=builddir" and test that.
- Would it be possible for media to have its own Makefile instead of
merging into this one?
Due to the way cleandocs target works, I had to rename the media DocBook
to media_api, otherwise cleandocs would remove the /media directory.
Thanks-to: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook/v4l/compat.xml')
| -rw-r--r-- | Documentation/DocBook/v4l/compat.xml | 2500 |
1 files changed, 0 insertions, 2500 deletions
diff --git a/Documentation/DocBook/v4l/compat.xml b/Documentation/DocBook/v4l/compat.xml deleted file mode 100644 index 9f7cd4f..0000000 --- a/Documentation/DocBook/v4l/compat.xml +++ /dev/null @@ -1,2500 +0,0 @@ - <title>Changes</title> - - <para>The following chapters document the evolution of the V4L2 API, -errata or extensions. They are also intended to help application and -driver writers to port or update their code.</para> - - <section id="diff-v4l"> - <title>Differences between V4L and V4L2</title> - - <para>The Video For Linux API was first introduced in Linux 2.1 to -unify and replace various TV and radio device related interfaces, -developed independently by driver writers in prior years. Starting -with Linux 2.5 the much improved V4L2 API replaces the V4L API, -although existing drivers will continue to support V4L applications in -the future, either directly or through the V4L2 compatibility layer in -the <filename>videodev</filename> kernel module translating ioctls on -the fly. For a transition period not all drivers will support the V4L2 -API.</para> - - <section> - <title>Opening and Closing Devices</title> - - <para>For compatibility reasons the character device file names -recommended for V4L2 video capture, overlay, radio and raw -vbi capture devices did not change from those used by V4L. They are -listed in <xref linkend="devices" /> and below in <xref - linkend="v4l-dev" />.</para> - - <para>The teletext devices (minor range 192-223) have been removed in -V4L2 and no longer exist. There is no hardware available anymore for handling -pure teletext. Instead raw or sliced VBI is used.</para> - - <para>The V4L <filename>videodev</filename> module automatically -assigns minor numbers to drivers in load order, depending on the -registered device type. We recommend that V4L2 drivers by default -register devices with the same numbers, but the system administrator -can assign arbitrary minor numbers using driver module options. The -major device number remains 81.</para> - - <table id="v4l-dev"> - <title>V4L Device Types, Names and Numbers</title> - <tgroup cols="3"> - <thead> - <row> - <entry>Device Type</entry> - <entry>File Name</entry> - <entry>Minor Numbers</entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry>Video capture and overlay</entry> - <entry><para><filename>/dev/video</filename> and -<filename>/dev/bttv0</filename><footnote> <para>According to -Documentation/devices.txt these should be symbolic links to -<filename>/dev/video0</filename>. Note the original bttv interface is -not compatible with V4L or V4L2.</para> </footnote>, -<filename>/dev/video0</filename> to -<filename>/dev/video63</filename></para></entry> - <entry>0-63</entry> - </row> - <row> - <entry>Radio receiver</entry> - <entry><para><filename>/dev/radio</filename><footnote> - <para>According to -<filename>Documentation/devices.txt</filename> a symbolic link to -<filename>/dev/radio0</filename>.</para> - </footnote>, <filename>/dev/radio0</filename> to -<filename>/dev/radio63</filename></para></entry> - <entry>64-127</entry> - </row> - <row> - <entry>Raw VBI capture</entry> - <entry><para><filename>/dev/vbi</filename>, -<filename>/dev/vbi0</filename> to -<filename>/dev/vbi31</filename></para></entry> - <entry>224-255</entry> - </row> - </tbody> - </tgroup> - </table> - - <para>V4L prohibits (or used to prohibit) multiple opens of a -device file. V4L2 drivers <emphasis>may</emphasis> support multiple -opens, see <xref linkend="open" /> for details and consequences.</para> - - <para>V4L drivers respond to V4L2 ioctls with an &EINVAL;. The -compatibility layer in the V4L2 <filename>videodev</filename> module -can translate V4L ioctl requests to their V4L2 counterpart, however a -V4L2 driver usually needs more preparation to become fully V4L -compatible. This is covered in more detail in <xref - linkend="driver" />.</para> - </section> - - <section> - <title>Querying Capabilities</title> - - <para>The V4L <constant>VIDIOCGCAP</constant> ioctl is -equivalent to V4L2's &VIDIOC-QUERYCAP;.</para> - - <para>The <structfield>name</structfield> field in struct -<structname>video_capability</structname> became -<structfield>card</structfield> in &v4l2-capability;, -<structfield>type</structfield> was replaced by -<structfield>capabilities</structfield>. Note V4L2 does not -distinguish between device types like this, better think of basic -video input, video output and radio devices supporting a set of -related functions like video capturing, video overlay and VBI -capturing. See <xref linkend="open" /> for an -introduction.<informaltable> - <tgroup cols="3"> - <thead> - <row> - <entry>struct -<structname>video_capability</structname> -<structfield>type</structfield></entry> - <entry>&v4l2-capability; -<structfield>capabilities</structfield> flags</entry> - <entry>Purpose</entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry><constant>VID_TYPE_CAPTURE</constant></entry> - <entry><constant>V4L2_CAP_VIDEO_CAPTURE</constant></entry> - <entry>The <link linkend="capture">video -capture</link> interface is supported.</entry> - </row> - <row> - <entry><constant>VID_TYPE_TUNER</constant></entry> - <entry><constant>V4L2_CAP_TUNER</constant></entry> - <entry>The device has a <link linkend="tuner">tuner or -modulator</link>.</entry> - </row> - <row> - <entry><constant>VID_TYPE_TELETEXT</constant></entry> - <entry><constant>V4L2_CAP_VBI_CAPTURE</constant></entry> - <entry>The <link linkend="raw-vbi">raw VBI -capture</link> interface is supported.</entry> - </row> - <row> - <entry><constant>VID_TYPE_OVERLAY</constant></entry> - <entry><constant>V4L2_CAP_VIDEO_OVERLAY</constant></entry> - <entry>The <link linkend="overlay">video -overlay</link> interface is supported.</entry> - </row> - <row> - <entry><constant>VID_TYPE_CHROMAKEY</constant></entry> - <entry><constant>V4L2_FBUF_CAP_CHROMAKEY</constant> in -field <structfield>capability</structfield> of -&v4l2-framebuffer;</entry> - <entry>Whether chromakey overlay is supported. For -more information on overlay see -<xref linkend="overlay" />.</entry> - </row> - <row> - <entry><constant>VID_TYPE_CLIPPING</constant></entry> - <entry><constant>V4L2_FBUF_CAP_LIST_CLIPPING</constant> -and <constant>V4L2_FBUF_CAP_BITMAP_CLIPPING</constant> in field -<structfield>capability</structfield> of &v4l2-framebuffer;</entry> - <entry>Whether clipping the overlaid image is -supported, see <xref linkend="overlay" />.</entry> - </row> - <row> - <entry><constant>VID_TYPE_FRAMERAM</constant></entry> - <entry><constant>V4L2_FBUF_CAP_EXTERNOVERLAY</constant> -<emphasis>not set</emphasis> in field -<structfield>capability</structfield> of &v4l2-framebuffer;</entry> - <entry>Whether overlay overwrites frame buffer memory, -see <xref linkend="overlay" />.</entry> - </row> - <row> - <entry><constant>VID_TYPE_SCALES</constant></entry> - <entry><constant>-</constant></entry> - <entry>This flag indicates if the hardware can scale -images. The V4L2 API implies the scale factor by setting the cropping -dimensions and image size with the &VIDIOC-S-CROP; and &VIDIOC-S-FMT; -ioctl, respectively. The driver returns the closest sizes possible. -For more information on cropping and scaling see <xref - linkend="crop" />.</entry> - </row> - <row> - <entry><constant>VID_TYPE_MONOCHROME</constant></entry> - <entry><constant>-</constant></entry> - <entry>Applications can enumerate the supported image -formats with the &VIDIOC-ENUM-FMT; ioctl to determine if the device -supports grey scale capturing only. For more information on image -formats see <xref linkend="pixfmt" />.</entry> - </row> - <row> - <entry><constant>VID_TYPE_SUBCAPTURE</constant></entry> - <entry><constant>-</constant></entry> - <entry>Applications can call the &VIDIOC-G-CROP; ioctl -to determine if the device supports capturing a subsection of the full -picture ("cropping" in V4L2). If not, the ioctl returns the &EINVAL;. -For more information on cropping and scaling see <xref - linkend="crop" />.</entry> - </row> - <row> - <entry><constant>VID_TYPE_MPEG_DECODER</constant></entry> - <entry><constant>-</constant></entry> - <entry>Applications can enumerate the supported image -formats with the &VIDIOC-ENUM-FMT; ioctl to determine if the device -supports MPEG streams.</entry> - </row> - <row> - <entry><constant>VID_TYPE_MPEG_ENCODER</constant></entry> - <entry><constant>-</constant></entry> - <entry>See above.</entry> - </row> - <row> - <entry><constant>VID_TYPE_MJPEG_DECODER</constant></entry> - <entry><constant>-</constant></entry> - <entry>See above.</entry> - </row> - <row> - <entry><constant>VID_TYPE_MJPEG_ENCODER</constant></entry> - <entry><constant>-</constant></entry> - <entry>See above.</entry> - </row> - </tbody> - </tgroup> - </informaltable></para> - - <para>The <structfield>audios</structfield> field was replaced -by <structfield>capabilities</structfield> flag -<constant>V4L2_CAP_AUDIO</constant>, indicating -<emphasis>if</emphasis> the device has any audio inputs or outputs. To -determine their number applications can enumerate audio inputs with -the &VIDIOC-G-AUDIO; ioctl. The audio ioctls are described in <xref - linkend="audio" />.</para> - - <para>The <structfield>maxwidth</structfield>, -<structfield>maxheight</structfield>, -<structfield>minwidth</structfield> and -<structfield>minheight</structfield> fields were removed. Calling the -&VIDIOC-S-FMT; or &VIDIOC-TRY-FMT; ioctl with the desired dimensions -returns the closest size possible, taking into account the current -video standard, cropping and scaling limitations.</para> - </section> - - <section> - <title>Video Sources</title> - - <para>V4L provides the <constant>VIDIOCGCHAN</constant> and -<constant>VIDIOCSCHAN</constant> ioctl using struct -<structname>video_channel</structname> to enumerate -the video inputs of a V4L device. The equivalent V4L2 ioctls -are &VIDIOC-ENUMINPUT;, &VIDIOC-G-INPUT; and &VIDIOC-S-INPUT; -using &v4l2-input; as discussed in <xref linkend="video" />.</para> - - <para>The <structfield>channel</structfield> field counting -inputs was renamed to <structfield>index</structfield>, the video -input types were renamed as follows: <informaltable> - <tgroup cols="2"> - <thead> - <row> - <entry>struct <structname>video_channel</structname> -<structfield>type</structfield></entry> - <entry>&v4l2-input; -<structfield>type</structfield></entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry><constant>VIDEO_TYPE_TV</constant></entry> - <entry><constant>V4L2_INPUT_TYPE_TUNER</constant></entry> - </row> - <row> - <entry><constant>VIDEO_TYPE_CAMERA</constant></entry> - <entry><constant>V4L2_INPUT_TYPE_CAMERA</constant></entry> - </row> - </tbody> - </tgroup> - </informaltable></para> - - <para>Unlike the <structfield>tuners</structfield> field -expressing the number of tuners of this input, V4L2 assumes each video -input is connected to at most one tuner. However a tuner can have more -than one input, &ie; RF connectors, and a device can have multiple -tuners. The index number of the tuner associated with the input, if -any, is stored in field <structfield>tuner</structfield> of -&v4l2-input;. Enumeration of tuners is discussed in <xref - linkend="tuner" />.</para> - - <para>The redundant <constant>VIDEO_VC_TUNER</constant> flag was -dropped. Video inputs associated with a tuner are of type -<constant>V4L2_INPUT_TYPE_TUNER</constant>. The -<constant>VIDEO_VC_AUDIO</constant> flag was replaced by the -<structfield>audioset</structfield> field. V4L2 considers devices with -up to 32 audio inputs. Each set bit in the -<structfield>audioset</structfield> field represents one audio input -this video input combines with. For information about audio inputs and -how to switch between them see <xref linkend="audio" />.</para> - - <para>The <structfield>norm</structfield> field describing the -supported video standards was replaced by -<structfield>std</structfield>. The V4L specification mentions a flag -<constant>VIDEO_VC_NORM</constant> indicating whether the standard can -be changed. This flag was a later addition together with the -<structfield>norm</structfield> field and has been removed in the -meantime. V4L2 has a similar, albeit more comprehensive approach -to video standards, see <xref linkend="standard" /> for more -information.</para> - </section> - - <section> - <title>Tuning</title> - - <para>The V4L <constant>VIDIOCGTUNER</constant> and -<constant>VIDIOCSTUNER</constant> ioctl and struct -<structname>video_tuner</structname> can be used to enumerate the -tuners of a V4L TV or radio device. The equivalent V4L2 ioctls are -&VIDIOC-G-TUNER; and &VIDIOC-S-TUNER; using &v4l2-tuner;. Tuners are -covered in <xref linkend="tuner" />.</para> - - <para>The <structfield>tuner</structfield> field counting tuners -was renamed to <structfield>index</structfield>. The fields -<structfield>name</structfield>, <structfield>rangelow</structfield> -and <structfield>rangehigh</structfield> remained unchanged.</para> - - <para>The <constant>VIDEO_TUNER_PAL</constant>, -<constant>VIDEO_TUNER_NTSC</constant> and -<constant>VIDEO_TUNER_SECAM</constant> flags indicating the supported -video standards were dropped. This information is now contained in the -associated &v4l2-input;. No replacement exists for the -<constant>VIDEO_TUNER_NORM</constant> flag indicating whether the -video standard can be switched. The <structfield>mode</structfield> -field to select a different video standard was replaced by a whole new -set of ioctls and structures described in <xref linkend="standard" />. -Due to its ubiquity it should be mentioned the BTTV driver supports -several standards in addition to the regular -<constant>VIDEO_MODE_PAL</constant> (0), -<constant>VIDEO_MODE_NTSC</constant>, -<constant>VIDEO_MODE_SECAM</constant> and -<constant>VIDEO_MODE_AUTO</constant> (3). Namely N/PAL Argentina, -M/PAL, N/PAL, and NTSC Japan with numbers 3-6 (sic).</para> - - <para>The <constant>VIDEO_TUNER_STEREO_ON</constant> flag -indicating stereo reception became -<constant>V4L2_TUNER_SUB_STEREO</constant> in field -<structfield>rxsubchans</structfield>. This field also permits the -detection of monaural and bilingual audio, see the definition of -&v4l2-tuner; for details. Presently no replacement exists for the -<constant>VIDEO_TUNER_RDS_ON</constant> and -<constant>VIDEO_TUNER_MBS_ON</constant> flags.</para> - - <para> The <constant>VIDEO_TUNER_LOW</constant> flag was renamed -to <constant>V4L2_TUNER_CAP_LOW</constant> in the &v4l2-tuner; -<structfield>capability</structfield> field.</para> - - <para>The <constant>VIDIOCGFREQ</constant> and -<constant>VIDIOCSFREQ</constant> ioctl to change the tuner frequency -where renamed to &VIDIOC-G-FREQUENCY; and &VIDIOC-S-FREQUENCY;. They -take a pointer to a &v4l2-frequency; instead of an unsigned long -integer.</para> - </section> - - <section id="v4l-image-properties"> - <title>Image Properties</title> - - <para>V4L2 has no equivalent of the -<constant>VIDIOCGPICT</constant> and <constant>VIDIOCSPICT</constant> -ioctl and struct <structname>video_picture</structname>. The following -fields where replaced by V4L2 controls accessible with the -&VIDIOC-QUERYCTRL;, &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls:<informaltable> - <tgroup cols="2"> - <thead> - <row> - <entry>struct <structname>video_picture</structname></entry> - <entry>V4L2 Control ID</entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry><structfield>brightness</structfield></entry> - <entry><constant>V4L2_CID_BRIGHTNESS</constant></entry> - </row> - <row> - <entry><structfield>hue</structfield></entry> - <entry><constant>V4L2_CID_HUE</constant></entry> - </row> - <row> - <entry><structfield>colour</structfield></entry> - <entry><constant>V4L2_CID_SATURATION</constant></entry> - </row> - <row> - <entry><structfield>contrast</structfield></entry> - <entry><constant>V4L2_CID_CONTRAST</constant></entry> - </row> - <row> - <entry><structfield>whiteness</structfield></entry> - <entry><constant>V4L2_CID_WHITENESS</constant></entry> - </row> - </tbody> - </tgroup> - </informaltable></para> - - <para>The V4L picture controls are assumed to range from 0 to -65535 with no particular reset value. The V4L2 API permits arbitrary -limits and defaults which can be queried with the &VIDIOC-QUERYCTRL; -ioctl. For general information about controls see <xref -linkend="control" />.</para> - - <para>The <structfield>depth</structfield> (average number of -bits per pixel) of a video image is implied by the selected image -format. V4L2 does not explicitely provide such information assuming -applications recognizing the format are aware of the image depth and -others need not know. The <structfield>palette</structfield> field -moved into the &v4l2-pix-format;:<informaltable> - <tgroup cols="2"> - <thead> - <row> - <entry>struct <structname>video_picture</structname> -<structfield>palette</structfield></entry> - <entry>&v4l2-pix-format; -<structfield>pixfmt</structfield></entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry><constant>VIDEO_PALETTE_GREY</constant></entry> - <entry><para><link -linkend="V4L2-PIX-FMT-GREY"><constant>V4L2_PIX_FMT_GREY</constant></link></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_HI240</constant></entry> - <entry><para><link -linkend="pixfmt-reserved"><constant>V4L2_PIX_FMT_HI240</constant></link><footnote> - <para>This is a custom format used by the BTTV -driver, not one of the V4L2 standard formats.</para> - </footnote></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_RGB565</constant></entry> - <entry><para><link -linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_RGB565</constant></link></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_RGB555</constant></entry> - <entry><para><link -linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_RGB555</constant></link></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_RGB24</constant></entry> - <entry><para><link -linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_BGR24</constant></link></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_RGB32</constant></entry> - <entry><para><link -linkend="pixfmt-rgb"><constant>V4L2_PIX_FMT_BGR32</constant></link><footnote> - <para>Presumably all V4L RGB formats are -little-endian, although some drivers might interpret them according to machine endianess. V4L2 defines little-endian, big-endian and red/blue -swapped variants. For details see <xref linkend="pixfmt-rgb" />.</para> - </footnote></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_YUV422</constant></entry> - <entry><para><link -linkend="V4L2-PIX-FMT-YUYV"><constant>V4L2_PIX_FMT_YUYV</constant></link></para></entry> - </row> - <row> - <entry><para><constant>VIDEO_PALETTE_YUYV</constant><footnote> - <para><constant>VIDEO_PALETTE_YUV422</constant> -and <constant>VIDEO_PALETTE_YUYV</constant> are the same formats. Some -V4L drivers respond to one, some to the other.</para> - </footnote></para></entry> - <entry><para><link -linkend="V4L2-PIX-FMT-YUYV"><constant>V4L2_PIX_FMT_YUYV</constant></link></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_UYVY</constant></entry> - <entry><para><link -linkend="V4L2-PIX-FMT-UYVY"><constant>V4L2_PIX_FMT_UYVY</constant></link></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_YUV420</constant></entry> - <entry>None</entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_YUV411</constant></entry> - <entry><para><link -linkend="V4L2-PIX-FMT-Y41P"><constant>V4L2_PIX_FMT_Y41P</constant></link><footnote> - <para>Not to be confused with -<constant>V4L2_PIX_FMT_YUV411P</constant>, which is a planar -format.</para> </footnote></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_RAW</constant></entry> - <entry><para>None<footnote> <para>V4L explains this -as: "RAW capture (BT848)"</para> </footnote></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_YUV422P</constant></entry> - <entry><para><link -linkend="V4L2-PIX-FMT-YUV422P"><constant>V4L2_PIX_FMT_YUV422P</constant></link></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_YUV411P</constant></entry> - <entry><para><link -linkend="V4L2-PIX-FMT-YUV411P"><constant>V4L2_PIX_FMT_YUV411P</constant></link><footnote> - <para>Not to be confused with -<constant>V4L2_PIX_FMT_Y41P</constant>, which is a packed -format.</para> </footnote></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_YUV420P</constant></entry> - <entry><para><link -linkend="V4L2-PIX-FMT-YVU420"><constant>V4L2_PIX_FMT_YVU420</constant></link></para></entry> - </row> - <row> - <entry><constant>VIDEO_PALETTE_YUV410P</constant></entry> - <entry><para><link -linkend="V4L2-PIX-FMT-YVU410"><constant>V4L2_PIX_FMT_YVU410</constant></link></para></entry> - </row> - </tbody> - </tgroup> - </informaltable></para> - - <para>V4L2 image formats are defined in <xref -linkend="pixfmt" />. The image format can be selected with the -&VIDIOC-S-FMT; ioctl.</para> - </section> - - <section> - <title>Audio</title> - - <para>The <constant>VIDIOCGAUDIO</constant> and -<constant>VIDIOCSAUDIO</constant> ioctl and struct -<structname>video_audio</structname> are used to enumerate the -audio inputs of a V4L device. The equivalent V4L2 ioctls are -&VIDIOC-G-AUDIO; and &VIDIOC-S-AUDIO; using &v4l2-audio; as -discussed in <xref linkend="audio" />.</para> - - <para>The <structfield>audio</structfield> "channel number" -field counting audio inputs was renamed to -<structfield>index</structfield>.</para> - - <para>On <constant>VIDIOCSAUDIO</constant> the -<structfield>mode</structfield> field selects <emphasis>one</emphasis> -of the <constant>VIDEO_SOUND_MONO</constant>, -<constant>VIDEO_SOUND_STEREO</constant>, -<constant>VIDEO_SOUND_LANG1</constant> or -<constant>VIDEO_SOUND_LANG2</constant> audio demodulation modes. When -the current audio standard is BTSC -<constant>VIDEO_SOUND_LANG2</constant> refers to SAP and -<constant>VIDEO_SOUND_LANG1</constant> is meaningless. Also -undocumented in the V4L specification, there is no way to query the -selected mode. On <constant>VIDIOCGAUDIO</constant> the driver returns -the <emphasis>actually received</emphasis> audio programmes in this -field. In the V4L2 API this information is stored in the &v4l2-tuner; -<structfield>rxsubchans</structfield> and -<structfield>audmode</structfield> fields, respectively. See <xref -linkend="tuner" /> for more information on tuners. Related to audio -modes &v4l2-audio; also reports if this is a mono or stereo -input, regardless if the source is a tuner.</para> - - <para>The following fields where replaced by V4L2 controls -accessible with the &VIDIOC-QUERYCTRL;, &VIDIOC-G-CTRL; and -&VIDIOC-S-CTRL; ioctls:<informaltable> - <tgroup cols="2"> - <thead> - <row> - <entry>struct -<structname>video_audio</structname></entry> - <entry>V4L2 Control ID</entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry><structfield>volume</structfield></entry> - <entry><constant>V4L2_CID_AUDIO_VOLUME</constant></entry> - </row> - <row> - <entry><structfield>bass</structfield></entry> - <entry><constant>V4L2_CID_AUDIO_BASS</constant></entry> - </row> - <row> - <entry><structfield>treble</structfield></entry> - <entry><constant>V4L2_CID_AUDIO_TREBLE</constant></entry> - </row> - <row> - <entry><structfield>balance</structfield></entry> - <entry><constant>V4L2_CID_AUDIO_BALANCE</constant></entry> - </row> - </tbody> - </tgroup> - </informaltable></para> - - <para>To determine which of these controls are supported by a -driver V4L provides the <structfield>flags</structfield> -<constant>VIDEO_AUDIO_VOLUME</constant>, -<constant>VIDEO_AUDIO_BASS</constant>, -<constant>VIDEO_AUDIO_TREBLE</constant> and -<constant>VIDEO_AUDIO_BALANCE</constant>. In the V4L2 API the -&VIDIOC-QUERYCTRL; ioctl reports if the respective control is -supported. Accordingly the <constant>VIDEO_AUDIO_MUTABLE</constant> -and <constant>VIDEO_AUDIO_MUTE</constant> flags where replaced by the -boolean <constant>V4L2_CID_AUDIO_MUTE</constant> control.</para> - - <para>All V4L2 controls have a <structfield>step</structfield> -attribute replacing the struct <structname>video_audio</structname> -<structfield>step</structfield> field. The V4L audio controls are -assumed to range from 0 to 65535 with no particular reset value. The -V4L2 API permits arbitrary limits and defaults which can be queried -with the &VIDIOC-QUERYCTRL; ioctl. For general information about -controls see <xref linkend="control" />.</para> - </section> - - <section> - <title>Frame Buffer Overlay</title> - - <para>The V4L2 ioctls equivalent to -<constant>VIDIOCGFBUF</constant> and <constant>VIDIOCSFBUF</constant> -are &VIDIOC-G-FBUF; and &VIDIOC-S-FBUF;. The -<structfield>base</structfield> field of struct -<structname>video_buffer</structname> remained unchanged, except V4L2 -defines a flag to indicate non-destructive overlays instead of a -<constant>NULL</constant> pointer. All other fields moved into the -&v4l2-pix-format; <structfield>fmt</structfield> substructure of -&v4l2-framebuffer;. The <structfield>depth</structfield> field was -replaced by <structfield>pixelformat</structfield>. See <xref - linkend="pixfmt-rgb" /> for a list of RGB formats and their -respective color depths.</para> - - <para>Instead of the special ioctls -<constant>VIDIOCGWIN</constant> and <constant>VIDIOCSWIN</constant> -V4L2 uses the general-purpose data format negotiation ioctls -&VIDIOC-G-FMT; and &VIDIOC-S-FMT;. They take a pointer to a -&v4l2-format; as argument. Here the <structfield>win</structfield> -member of the <structfield>fmt</structfield> union is used, a -&v4l2-window;.</para> - - <para>The <structfield>x</structfield>, -<structfield>y</structfield>, <structfield>width</structfield> and -<structfield>height</structfield> fields of struct -<structname>video_window</structname> moved into &v4l2-rect; -substructure <structfield>w</structfield> of struct -<structname>v4l2_window</structname>. The -<structfield>chromakey</structfield>, -<structfield>clips</structfield>, and -<structfield>clipcount</structfield> fields remained unchanged. Struct -<structname>video_clip</structname> was renamed to &v4l2-clip;, also -containing a struct <structname>v4l2_rect</structname>, but the -semantics are still the same.</para> - - <para>The <constant>VIDEO_WINDOW_INTERLACE</constant> flag was -dropped. Instead applications must set the -<structfield>field</structfield> field to -<constant>V4L2_FIELD_ANY</constant> or -<constant>V4L2_FIELD_INTERLACED</constant>. The -<constant>VIDEO_WINDOW_CHROMAKEY</constant> flag moved into -&v4l2-framebuffer;, under the new name -<constant>V4L2_FBUF_FLAG_CHROMAKEY</constant>.</para> - - <para>In V4L, storing a bitmap pointer in -<structfield>clips</structfield> and setting -<structfield>clipcount</structfield> to -<constant>VIDEO_CLIP_BITMAP</constant> (-1) requests bitmap -clipping, using a fixed size bitmap of 1024 × 625 bits. Struct -<structname>v4l2_window</structname> has a separate -<structfield>bitmap</structfield> pointer field for this purpose and -the bitmap size is determined by <structfield>w.width</structfield> and -<structfield>w.height</structfield>.</para> - - <para>The <constant>VIDIOCCAPTURE</constant> ioctl to enable or -disable overlay was renamed to &VIDIOC-OVERLAY;.</para> - </section> - - <section> - <title>Cropping</title> - - <para>To capture only a subsection of the full picture V4L -defines the <constant>VIDIOCGCAPTURE</constant> and -<constant>VIDIOCSCAPTURE</constant> ioctls using struct -<structname>video_capture</structname>. The equivalent V4L2 ioctls are -&VIDIOC-G-CROP; and &VIDIOC-S-CROP; using &v4l2-crop;, and the related -&VIDIOC-CROPCAP; ioctl. This is a rather complex matter, see -<xref linkend="crop" /> for details.</para> - - <para>The <structfield>x</structfield>, -<structfield>y</structfield>, <structfield>width</structfield> and -<structfield>height</structfield> fields moved into &v4l2-rect; -substructure <structfield>c</structfield> of struct -<structname>v4l2_crop</structname>. The -<structfield>decimation</structfield> field was dropped. In the V4L2 -API the scaling factor is implied by the size of the cropping -rectangle and the size of the captured or overlaid image.</para> - - <para>The <constant>VIDEO_CAPTURE_ODD</constant> -and <constant>VIDEO_CAPTURE_EVEN</constant> flags to capture only the -odd or even field, respectively, were replaced by -<constant>V4L2_FIELD_TOP</constant> and -<constant>V4L2_FIELD_BOTTOM</constant> in the field named -<structfield>field</structfield> of &v4l2-pix-format; and -&v4l2-window;. These structures are used to select a capture or -overlay format with the &VIDIOC-S-FMT; ioctl.</para> - </section> - - <section> - <title>Reading Images, Memory Mapping</title> - - <section> - <title>Capturing using the read method</title> - - <para>There is no essential difference between reading images -from a V4L or V4L2 device using the &func-read; function, however V4L2 -drivers are not required to support this I/O method. Applications can -determine if the function is available with the &VIDIOC-QUERYCAP; -ioctl. All V4L2 devices exchanging data with applications must support -the &func-select; and &func-poll; functions.</para> - - <para>To select an image format and size, V4L provides the -<constant>VIDIOCSPICT</constant> and <constant>VIDIOCSWIN</constant> -ioctls. V4L2 uses the general-purpose data format negotiation ioctls -&VIDIOC-G-FMT; and &VIDIOC-S-FMT;. They take a pointer to a -&v4l2-format; as argument, here the &v4l2-pix-format; named -<structfield>pix</structfield> of its <structfield>fmt</structfield> -union is used.</para> - - <para>For more information about the V4L2 read interface see -<xref linkend="rw" />.</para> - </section> - <section> - <title>Capturing using memory mapping</title> - - <para>Applications can read from V4L devices by mapping -buffers in device memory, or more often just buffers allocated in -DMA-able system memory, into their address space. This avoids the data -copying overhead of the read method. V4L2 supports memory mapping as -well, with a few differences.</para> - - <informaltable> - <tgroup cols="2"> - <thead> - <row> - <entry>V4L</entry> - <entry>V4L2</entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry></entry> - <entry>The image format must be selected before -buffers are allocated, with the &VIDIOC-S-FMT; ioctl. When no format -is selected the driver may use the last, possibly by another -application requested format.</entry> - </row> - <row> - <entry><para>Applications cannot change the number of -buffers. The it is built into the driver, unless it has a module -option to change the number when the driver module is -loaded.</para></entry> - <entry><para>The &VIDIOC-REQBUFS; ioctl allocates the -desired number of buffers, this is a required step in the initialization -sequence.</para></entry> - </row> - <row> - <entry><para>Drivers map all buffers as one contiguous -range of memory. The <constant>VIDIOCGMBUF</constant> ioctl is -available to query the number of buffers, the offset of each buffer -from the start of the virtual file, and the overall amount of memory -used, which can be used as arguments for the &func-mmap; -function.</para></entry> - <entry><para>Buffers are individually mapped. The -offset and size of each buffer can be determined with the -&VIDIOC-QUERYBUF; ioctl.</para></entry> - </row> - <row> - <entry><para>The <constant>VIDIOCMCAPTURE</constant> -ioctl prepares a buffer for capturing. It also determines the image -format for this buffer. The ioctl returns immediately, eventually with -an &EAGAIN; if no video signal had been detected. When the driver -supports more than one buffer applications can call the ioctl multiple -times and thus have multiple outstanding capture -requests.</para><para>The <constant>VIDIOCSYNC</constant> ioctl -suspends execution until a particular buffer has been -filled.</para></entry> - <entry><para>Drivers maintain an incoming and outgoing -queue. &VIDIOC-QBUF; enqueues any empty buffer into the incoming -queue. Filled buffers are dequeued from the outgoing queue with the -&VIDIOC-DQBUF; ioctl. To wait until filled buffers become available this -function, &func-select; or &func-poll; can be used. The -&VIDIOC-STREAMON; ioctl must be called once after enqueuing one or -more buffers to start capturing. Its counterpart -&VIDIOC-STREAMOFF; stops capturing and dequeues all buffers from both -queues. Applications can query the signal status, if known, with the -&VIDIOC-ENUMINPUT; ioctl.</para></entry> - </row> - </tbody> - </tgroup> - </informaltable> - - <para>For a more in-depth discussion of memory mapping and -examples, see <xref linkend="mmap" />.</para> - </section> - </section> - - <section> - <title>Reading Raw VBI Data</title> - - <para>Originally the V4L API did not specify a raw VBI capture -interface, only the device file <filename>/dev/vbi</filename> was -reserved for this purpose. The only driver supporting this interface -was the BTTV driver, de-facto defining the V4L VBI interface. Reading -from the device yields a raw VBI image with the following -parameters:<informaltable> - <tgroup cols="2"> - <thead> - <row> - <entry>&v4l2-vbi-format;</entry> - <entry>V4L, BTTV driver</entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry>sampling_rate</entry> - <entry>28636363 Hz NTSC (or any other 525-line -standard); 35468950 Hz PAL and SECAM (625-line standards)</entry> - </row> - <row> - <entry>offset</entry> - <entry>?</entry> - </row> - <row> - <entry>samples_per_line</entry> - <entry>2048</entry> - </row> - <row> - <entry>sample_format</entry> - <entry>V4L2_PIX_FMT_GREY. The last four bytes (a -machine endianess integer) contain a frame counter.</entry> - </row> - <row> - <entry>start[]</entry> - <entry>10, 273 NTSC; 22, 335 PAL and SECAM</entry> - </row> - <row> - <entry>count[]</entry> - <entry><para>16, 16<footnote><para>Old driver -versions used different values, eventually the custom -<constant>BTTV_VBISIZE</constant> ioctl was added to query the -correct values.</para></footnote></para></entry> - </row> - <row> - <entry>flags</entry> - <entry>0</entry> - </row> - </tbody> - </tgroup> - </informaltable></para> - - <para>Undocumented in the V4L specification, in Linux 2.3 the -<constant>VIDIOCGVBIFMT</constant> and -<constant>VIDIOCSVBIFMT</constant> ioctls using struct -<structname>vbi_format</structname> were added to determine the VBI -image parameters. These ioctls are only partially compatible with the -V4L2 VBI interface specified in <xref linkend="raw-vbi" />.</para> - - <para>An <structfield>offset</structfield> field does not -exist, <structfield>sample_format</structfield> is supposed to be -<constant>VIDEO_PALETTE_RAW</constant>, equivalent to -<constant>V4L2_PIX_FMT_GREY</constant>. The remaining fields are -probably equivalent to &v4l2-vbi-format;.</para> - - <para>Apparently only the Zoran (ZR 36120) driver implements -these ioctls. The semantics differ from those specified for V4L2 in two -ways. The parameters are reset on &func-open; and -<constant>VIDIOCSVBIFMT</constant> always returns an &EINVAL; if the -parameters are invalid.</para> - </section> - - <section> - <title>Miscellaneous</title> - - <para>V4L2 has no equivalent of the -<constant>VIDIOCGUNIT</constant> ioctl. Applications can find the VBI -device associated with a video capture device (or vice versa) by -reopening the device and requesting VBI data. For details see -<xref linkend="open" />.</para> - - <para>No replacement exists for <constant>VIDIOCKEY</constant>, -and the V4L functions for microcode programming. A new interface for -MPEG compression and playback devices is documented in <xref - linkend="extended-controls" />.</para> - </section> - - </section> - - <section id="hist-v4l2"> - <title>Changes of the V4L2 API</title> - - <para>Soon after the V4L API was added to the kernel it was -criticised as too inflexible. In August 1998 Bill Dirks proposed a -number of improvements and began to work on documentation, example -drivers and applications. With the help of other volunteers this -eventually became the V4L2 API, not just an extension but a -replacement for the V4L API. However it took another four years and -two stable kernel releases until the new API was finally accepted for -inclusion into the kernel in its present form.</para> - - <section> - <title>Early Versions</title> - <para>1998-08-20: First version.</para> - - <para>1998-08-27: The &func-select; function was introduced.</para> - - <para>1998-09-10: New video standard interface.</para> - - <para>1998-09-18: The <constant>VIDIOC_NONCAP</constant> ioctl -was replaced by the otherwise meaningless <constant>O_TRUNC</constant> -&func-open; flag, and the aliases <constant>O_NONCAP</constant> and -<constant>O_NOIO</constant> were defined. Applications can set this -flag if they intend to access controls only, as opposed to capture -applications which need exclusive access. The -<constant>VIDEO_STD_XXX</constant> identifiers are now ordinals -instead of flags, and the <function>video_std_construct()</function> -helper function takes id and transmission arguments.</para> - - <para>1998-09-28: Revamped video standard. Made video controls -individually enumerable.</para> - - <para>1998-10-02: The <structfield>id</structfield> field was -removed from struct <structname>video_standard</structname> and the -color subcarrier fields were renamed. The &VIDIOC-QUERYSTD; ioctl was -renamed to &VIDIOC-ENUMSTD;, &VIDIOC-G-INPUT; to &VIDIOC-ENUMINPUT;. A -first draft of the Codec API was released.</para> - - <para>1998-11-08: Many minor changes. Most symbols have been -renamed. Some material changes to &v4l2-capability;.</para> - - <para>1998-11-12: The read/write directon of some ioctls was misdefined.</para> - - <para>1998-11-14: <constant>V4L2_PIX_FMT_RGB24</constant> -changed to <constant>V4L2_PIX_FMT_BGR24</constant>, and -<constant>V4L2_PIX_FMT_RGB32</constant> changed to -<constant>V4L2_PIX_FMT_BGR32</constant>. Audio controls are now -accessible with the &VIDIOC-G-CTRL; and &VIDIOC-S-CTRL; ioctls under -names starting with <constant>V4L2_CID_AUDIO</constant>. The -<constant>V4L2_MAJOR</constant> define was removed from -<filename>videodev.h</filename> since it was only used once in the -<filename>videodev</filename> kernel module. The -<constant>YUV422</constant> and <constant>YUV411</constant> planar -image formats were added.</para> - - <para>1998-11-28: A few ioctl symbols changed. Interfaces for codecs and -video output devices were added.</para> - - <para>1999-01-14: A raw VBI capture interface was added.</para> - - <para>1999-01-19: The <constant>VIDIOC_NEXTBUF</constant> ioctl - was removed.</para> - </section> - - <section> - <title>V4L2 Version 0.16 1999-01-31</title> - <para>1999-01-27: There is now one QBUF ioctl, VIDIOC_QWBUF and VIDIOC_QRBUF -are gone. VIDIOC_QBUF takes a v4l2_buffer as a parameter. Added -digital zoom (cropping) controls.</para> - </section> - - <!-- Where's 0.17? mhs couldn't find that videodev.h, perhaps Bill - forgot to bump the version number or never released it. --> - - <section> - <title>V4L2 Version 0.18 1999-03-16</title> - <para>Added a v4l to V4L2 ioctl compatibility layer to -videodev.c. Driver writers, this changes how you implement your ioctl -handler. See the Driver Writer's Guide. Added some more control id -codes.</para> - </section> - - <section> - <title>V4L2 Version 0.19 1999-06-05</title> - <para>1999-03-18: Fill in the category and catname fields of -v4l2_queryctrl objects before passing them to the driver. Required a -minor change to the VIDIOC_QUERYCTRL handlers in the sample -drivers.</para> - <para>1999-03-31: Better compatibility for v4l memory capture -ioctls. Requires changes to drivers to fully support new compatibility -features, see Driver Writer's Guide and v4l2cap.c. Added new control -IDs: V4L2_CID_HFLIP, _VFLIP. Changed V4L2_PIX_FMT_YUV422P to _YUV422P, -and _YUV411P to _YUV411P.</para> - <para>1999-04-04: Added a few more control IDs.</para> - <para>1999-04-07: Added the button control type.</para> - <para>1999-05-02: Fixed a typo in videodev.h, and added the -V4L2_CTRL_FLAG_GRAYED (later V4L2_CTRL_FLAG_GRABBED) flag.</para> - <para>1999-05-20: Definition of VIDIOC_G_CTRL was wrong causing -a malfunction of this ioctl.</para> - <para>1999-06-05: Changed the value of -V4L2_CID_WHITENESS.</para> - </section> - - <section> - <title>V4L2 Version 0.20 (1999-09-10)</title> - - <para>Version 0.20 introduced a number of changes which were -<emphasis>not backward compatible</emphasis> with 0.19 and earlier -versions. Purpose of these changes was to simplify the API, while -making it more extensible and following common Linux driver API -conventions.</para> - - <orderedlist> - <listitem> - <para>Some typos in <constant>V4L2_FMT_FLAG</constant> -symbols were fixed. &v4l2-clip; was changed for compatibility with -v4l. (1999-08-30)</para> - </listitem> - - <listitem> - <para><constant>V4L2_TUNER_SUB_LANG1</constant> was added. -(1999-09-05)</para> - </listitem> - - <listitem> - <para>All ioctl() commands that used an integer argument now -take a pointer to an integer. Where it makes sense, ioctls will return -the actual new value in the integer pointed to by the argument, a -common convention in the V4L2 API. The affected ioctls are: -VIDIOC_PREVIEW, VIDIOC_STREAMON, VIDIOC_STREAMOFF, VIDIOC_S_FREQ, -VIDIOC_S_INPUT, VIDIOC_S_OUTPUT, VIDIOC_S_EFFECT. For example -<programlisting> -err = ioctl (fd, VIDIOC_XXX, V4L2_XXX); -</programlisting> becomes <programlisting> -int a = V4L2_XXX; err = ioctl(fd, VIDIOC_XXX, &a); -</programlisting> - </para> - </listitem> - - <listitem> - <para>All the different get- and set-format commands were -swept into one &VIDIOC-G-FMT; and &VIDIOC-S-FMT; ioctl taking a union -and a type field selecting the union member as parameter. Purpose is to -simplify the API by eliminating several ioctls and to allow new and -driver private data streams without adding new ioctls.</para> - - <para>This change obsoletes the following ioctls: -<constant>VIDIOC_S_INFMT</constant>, -<constant>VIDIOC_G_INFMT</constant>, -<constant>VIDIOC_S_OUTFMT</constant>, -<constant>VIDIOC_G_OUTFMT</constant>, -<constant>VIDIOC_S_VBIFMT</constant> and -<constant>VIDIOC_G_VBIFMT</constant>. The image format structure -<structname>v4l2_format</structname> was renamed to &v4l2-pix-format;, -while &v4l2-format; is now the envelopping structure for all format -negotiations.</para> - </listitem> - - <listitem> - <para>Similar to the changes above, the -<constant>VIDIOC_G_PARM</constant> and -<constant>VIDIOC_S_PARM</constant> ioctls were merged with -<constant>VIDIOC_G_OUTPARM</constant> and -<constant>VIDIOC_S_OUTPARM</constant>. A -<structfield>type</structfield> field in the new &v4l2-streamparm; -selects the respective union member.</para> - - <para>This change obsoletes the -<constant>VIDIOC_G_OUTPARM</constant> and -<constant>VIDIOC_S_OUTPARM</constant> ioctls.</para> - </listitem> - - <listitem> - <para>Control enumeration was simplified, and two new -control flags were introduced and one dropped. The -<structfield>catname</structfield> field was replaced by a -<structfield>group</structfield> field.</para> - - <para>Drivers can now flag unsupported and temporarily -unavailable controls with <constant>V4L2_CTRL_FLAG_DISABLED</constant> -and <constant>V4L2_CTRL_FLAG_GRABBED</constant> respectively. The -<structfield>group</structfield> name indicates a possibly narrower -classification than the <structfield>category</structfield>. In other -words, there may be multiple groups within a category. Controls within -a group would typically be drawn within a group box. Controls in -different categories might have a greater separation, or may even -appear in separate windows.</para> - </listitem> - - <listitem> - <para>The &v4l2-buffer; <structfield>timestamp</structfield> -was changed to a 64 bit integer, containing the sampling or output -time of the frame in nanoseconds. Additionally timestamps will be in -absolute system time, not starting from zero at the beginning of a -stream. The data type name for timestamps is stamp_t, defined as a -signed 64-bit integer. Output devices should not send a buffer out -until the time in the timestamp field has arrived. I would like to -follow SGI's lead, and adopt a multimedia timestamping system like -their UST (Unadjusted System Time). See -http://web.archive.org/web/*/http://reality.sgi.com -/cpirazzi_engr/lg/time/intro.html. -UST uses timestamps that are 64-bit signed integers -(not struct timeval's) and given in nanosecond units. The UST clock -starts at zero when the system is booted and runs continuously and -uniformly. It takes a little over 292 years for UST to overflow. There -is no way to set the UST clock. The regular Linux time-of-day clock -can be changed periodically, which would cause errors if it were being -used for timestamping a multimedia stream. A real UST style clock will -require some support in the kernel that is not there yet. But in -anticipation, I will change the timestamp field to a 64-bit integer, -and I will change the v4l2_masterclock_gettime() function (used only -by drivers) to return a 64-bit integer.</para> - </listitem> - - <listitem> - <para>A <structfield>sequence</structfield> field was added -to &v4l2-buffer;. The <structfield>sequence</structfield> field counts -captured frames, it is ignored by output devices. When a capture -driver drops a frame, the sequence number of that frame is -skipped.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 Version 0.20 incremental changes</title> - <!-- Version number didn't change anymore, reason unknown. --> - - <para>1999-12-23: In &v4l2-vbi-format; the -<structfield>reserved1</structfield> field became -<structfield>offset</structfield>. Previously drivers were required to -clear the <structfield>reserved1</structfield> field.</para> - - <para>2000-01-13: The - <constant>V4L2_FMT_FLAG_NOT_INTERLACED</constant> flag was added.</para> - - <para>2000-07-31: The <filename>linux/poll.h</filename> header -is now included by <filename>videodev.h</filename> for compatibility -with the original <filename>videodev.h</filename> file.</para> - - <para>2000-11-20: <constant>V4L2_TYPE_VBI_OUTPUT</constant> and -<constant>V4L2_PIX_FMT_Y41P</constant> were added.</para> - - <para>2000-11-25: <constant>V4L2_TYPE_VBI_INPUT</constant> was -added.</para> - - <para>2000-12-04: A couple typos in symbol names were fixed.</para> - - <para>2001-01-18: To avoid namespace conflicts the -<constant>fourcc</constant> macro defined in the -<filename>videodev.h</filename> header file was renamed to -<constant>v4l2_fourcc</constant>.</para> - - <para>2001-01-25: A possible driver-level compatibility problem -between the <filename>videodev.h</filename> file in Linux 2.4.0 and -the <filename>videodev.h</filename> file included in the -<filename>videodevX</filename> patch was fixed. Users of an earlier -version of <filename>videodevX</filename> on Linux 2.4.0 should -recompile their V4L and V4L2 drivers.</para> - - <para>2001-01-26: A possible kernel-level incompatibility -between the <filename>videodev.h</filename> file in the -<filename>videodevX</filename> patch and the -<filename>videodev.h</filename> file in Linux 2.2.x with devfs patches -applied was fixed.</para> - - <para>2001-03-02: Certain V4L ioctls which pass data in both -direction although they are defined with read-only parameter, did not -work correctly through the backward compatibility layer. -[Solution?]</para> - - <para>2001-04-13: Big endian 16-bit RGB formats were added.</para> - - <para>2001-09-17: New YUV formats and the &VIDIOC-G-FREQUENCY; and -&VIDIOC-S-FREQUENCY; ioctls were added. (The old -<constant>VIDIOC_G_FREQ</constant> and -<constant>VIDIOC_S_FREQ</constant> ioctls did not take multiple tuners -into account.)</para> - - <para>2000-09-18: <constant>V4L2_BUF_TYPE_VBI</constant> was -added. This may <emphasis>break compatibility</emphasis> as the -&VIDIOC-G-FMT; and &VIDIOC-S-FMT; ioctls may fail now if the struct -<structname>v4l2_fmt</structname> <structfield>type</structfield> -field does not contain <constant>V4L2_BUF_TYPE_VBI</constant>. In the -documentation of the &v4l2-vbi-format; -<structfield>offset</structfield> field the ambiguous phrase "rising -edge" was changed to "leading edge".</para> - </section> - - <section> - <title>V4L2 Version 0.20 2000-11-23</title> - - <para>A number of changes were made to the raw VBI -interface.</para> - - <orderedlist> - <listitem> - <para>Figures clarifying the line numbering scheme were -added to the V4L2 API specification. The -<structfield>start</structfield>[0] and -<structfield>start</structfield>[1] fields no longer count line -numbers beginning at zero. Rationale: a) The previous definition was -unclear. b) The <structfield>start</structfield>[] values are ordinal -numbers. c) There is no point in inventing a new line numbering -scheme. We now use line number as defined by ITU-R, period. -Compatibility: Add one to the start values. Applications depending on -the previous semantics may not function correctly.</para> - </listitem> - - <listitem> - <para>The restriction "count[0] > 0 and count[1] > 0" -has been relaxed to "(count[0] + count[1]) > 0". Rationale: -Drivers may allocate resources at scan line granularity and some data -services are transmitted only on the first field. The comment that -both <structfield>count</structfield> values will usually be equal is -misleading and pointless and has been removed. This change -<emphasis>breaks compatibility</emphasis> with earlier versions: -Drivers may return EINVAL, applications may not function -correctly.</para> - </listitem> - - <listitem> - <para>Drivers are again permitted to return negative -(unknown) start values as proposed earlier. Why this feature was -dropped is unclear. This change may <emphasis>break -compatibility</emphasis> with applications depending on the start -values being positive. The use of <constant>EBUSY</constant> and -<constant>EINVAL</constant> error codes with the &VIDIOC-S-FMT; ioctl -was clarified. The &EBUSY; was finally documented, and the -<structfield>reserved2</structfield> field which was previously -mentioned only in the <filename>videodev.h</filename> header -file.</para> - </listitem> - - <listitem> - <para>New buffer types -<constant>V4L2_TYPE_VBI_INPUT</constant> and -<constant>V4L2_TYPE_VBI_OUTPUT</constant> were added. The former is an -alias for the old <constant>V4L2_TYPE_VBI</constant>, the latter was -missing in the <filename>videodev.h</filename> file.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 Version 0.20 2002-07-25</title> - <para>Added sliced VBI interface proposal.</para> - </section> - - <section> - <title>V4L2 in Linux 2.5.46, 2002-10</title> - - <para>Around October-November 2002, prior to an announced -feature freeze of Linux 2.5, the API was revised, drawing from -experience with V4L2 0.20. This unnamed version was finally merged -into Linux 2.5.46.</para> - - <orderedlist> - <listitem> - <para>As specified in <xref linkend="related" />, drivers -must make related device functions available under all minor device -numbers.</para> - </listitem> - - <listitem> - <para>The &func-open; function requires access mode -<constant>O_RDWR</constant> regardless of the device type. All V4L2 -drivers exchanging data with applications must support the -<constant>O_NONBLOCK</constant> flag. The <constant>O_NOIO</constant> -flag, a V4L2 symbol which aliased the meaningless -<constant>O_TRUNC</constant> to indicate accesses without data -exchange (panel applications) was dropped. Drivers must stay in "panel -mode" until the application attempts to initiate a data exchange, see -<xref linkend="open" />.</para> - </listitem> - - <listitem> - <para>The &v4l2-capability; changed dramatically. Note that -also the size of the structure changed, which is encoded in the ioctl -request code, thus older V4L2 devices will respond with an &EINVAL; to -the new &VIDIOC-QUERYCAP; ioctl.</para> - - <para>There are new fields to identify the driver, a new RDS -device function <constant>V4L2_CAP_RDS_CAPTURE</constant>, the -<constant>V4L2_CAP_AUDIO</constant> flag indicates if the device has -any audio connectors, another I/O capability -<constant>V4L2_CAP_ASYNCIO</constant> can be flagged. In response to -these changes the <structfield>type</structfield> field became a bit -set and was merged into the <structfield>flags</structfield> field. -<constant>V4L2_FLAG_TUNER</constant> was renamed to -<constant>V4L2_CAP_TUNER</constant>, -<constant>V4L2_CAP_VIDEO_OVERLAY</constant> replaced -<constant>V4L2_FLAG_PREVIEW</constant> and -<constant>V4L2_CAP_VBI_CAPTURE</constant> and -<constant>V4L2_CAP_VBI_OUTPUT</constant> replaced -<constant>V4L2_FLAG_DATA_SERVICE</constant>. -<constant>V4L2_FLAG_READ</constant> and -<constant>V4L2_FLAG_WRITE</constant> were merged into -<constant>V4L2_CAP_READWRITE</constant>.</para> - - <para>The redundant fields -<structfield>inputs</structfield>, <structfield>outputs</structfield> -and <structfield>audios</structfield> were removed. These properties -can be determined as described in <xref linkend="video" /> and <xref -linkend="audio" />.</para> - - <para>The somewhat volatile and therefore barely useful -fields <structfield>maxwidth</structfield>, -<structfield>maxheight</structfield>, -<structfield>minwidth</structfield>, -<structfield>minheight</structfield>, -<structfield>maxframerate</structfield> were removed. This information -is available as described in <xref linkend="format" /> and -<xref linkend="standard" />.</para> - - <para><constant>V4L2_FLAG_SELECT</constant> was removed. We -believe the select() function is important enough to require support -of it in all V4L2 drivers exchanging data with applications. The -redundant <constant>V4L2_FLAG_MONOCHROME</constant> flag was removed, -this information is available as described in <xref - linkend="format" />.</para> - </listitem> - - <listitem> - <para>In &v4l2-input; the -<structfield>assoc_audio</structfield> field and the -<structfield>capability</structfield> field and its only flag -<constant>V4L2_INPUT_CAP_AUDIO</constant> was replaced by the new -<structfield>audioset</structfield> field. Instead of linking one -video input to one audio input this field reports all audio inputs -this video input combines with.</para> - - <para>New fields are <structfield>tuner</structfield> -(reversing the former link from tuners to video inputs), -<structfield>std</structfield> and -<structfield>status</structfield>.</para> - - <para>Accordingly &v4l2-output; lost its -<structfield>capability</structfield> and -<structfield>assoc_audio</structfield> fields. -<structfield>audioset</structfield>, -<structfield>modulator</structfield> and -<structfield>std</structfield> where added instead.</para> - </listitem> - - <listitem> - <para>The &v4l2-audio; field -<structfield>audio</structfield> was renamed to -<structfield>index</structfield>, for consistency with other -structures. A new capability flag -<constant>V4L2_AUDCAP_STEREO</constant> was added to indicated if the -audio input in question supports stereo sound. -<constant>V4L2_AUDCAP_EFFECTS</constant> and the corresponding -<constant>V4L2_AUDMODE</constant> flags where removed. This can be -easily implemented using controls. (However the same applies to AVL -which is still there.)</para> - - <para>Again for consistency the &v4l2-audioout; field -<structfield>audio</structfield> was renamed to -<structfield>index</structfield>.</para> - </listitem> - - <listitem> - <para>The &v4l2-tuner; -<structfield>input</structfield> field was replaced by an -<structfield>index</structfield> field, permitting devices with -multiple tuners. The link between video inputs and tuners is now -reversed, inputs point to their tuner. The -<structfield>std</structfield> substructure became a -simple set (more about this below) and moved into &v4l2-input;. A -<structfield>type</structfield> field was added.</para> - - <para>Accordingly in &v4l2-modulator; the -<structfield>output</structfield> was replaced by an -<structfield>index</structfield> field.</para> - - <para>In &v4l2-frequency; the -<structfield>port</structfield> field was replaced by a -<structfield>tuner</structfield> field containing the respective tuner -or modulator index number. A tuner <structfield>type</structfield> -field was added and the <structfield>reserved</structfield> field -became larger for future extensions (satellite tuners in -particular).</para> - </listitem> - - <listitem> - <para>The idea of completely transparent video standards was -dropped. Experience showed that applications must be able to work with -video standards beyond presenting the user a menu. Instead of -enumerating supported standards with an ioctl applications can now -refer to standards by &v4l2-std-id; and symbols defined in the -<filename>videodev2.h</filename> header file. For details see <xref - linkend="standard" />. The &VIDIOC-G-STD; and -&VIDIOC-S-STD; now take a pointer to this type as argument. -&VIDIOC-QUERYSTD; was added to autodetect the received standard, if -the hardware has this capability. In &v4l2-standard; an -<structfield>index</structfield> field was added for &VIDIOC-ENUMSTD;. -A &v4l2-std-id; field named <structfield>id</structfield> was added as -machine readable identifier, also replacing the -<structfield>transmission</structfield> field. The misleading -<structfield>framerate</structfield> field was renamed -to <structfield>frameperiod</structfield>. The now obsolete -<structfield>colorstandard</structfield> information, originally -needed to distguish between variations of standards, were -removed.</para> - - <para>Struct <structname>v4l2_enumstd</structname> ceased to -be. &VIDIOC-ENUMSTD; now takes a pointer to a &v4l2-standard; -directly. The information which standards are supported by a -particular video input or output moved into &v4l2-input; and -&v4l2-output; fields named <structfield>std</structfield>, -respectively.</para> - </listitem> - - <listitem> - <para>The &v4l2-queryctrl; fields -<structfield>category</structfield> and -<structfield>group</structfield> did not catch on and/or were not -implemented as expected and therefore removed.</para> - </listitem> - - <listitem> - <para>The &VIDIOC-TRY-FMT; ioctl was added to negotiate data -formats as with &VIDIOC-S-FMT;, but without the overhead of -programming the hardware and regardless of I/O in progress.</para> - - <para>In &v4l2-format; the <structfield>fmt</structfield> -union was extended to contain &v4l2-window;. All image format -negotiations are now possible with <constant>VIDIOC_G_FMT</constant>, -<constant>VIDIOC_S_FMT</constant> and -<constant>VIDIOC_TRY_FMT</constant>; ioctl. The -<constant>VIDIOC_G_WIN</constant> and -<constant>VIDIOC_S_WIN</constant> ioctls to prepare for a video -overlay were removed. The <structfield>type</structfield> field -changed to type &v4l2-buf-type; and the buffer type names changed as -follows.<informaltable> - <tgroup cols="2"> - <thead> - <row> - <entry>Old defines</entry> - <entry>&v4l2-buf-type;</entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry><constant>V4L2_BUF_TYPE_CAPTURE</constant></entry> - <entry><constant>V4L2_BUF_TYPE_VIDEO_CAPTURE</constant></entry> - </row> - <row> - <entry><constant>V4L2_BUF_TYPE_CODECIN</constant></entry> - <entry>Omitted for now</entry> - </row> - <row> - <entry><constant>V4L2_BUF_TYPE_CODECOUT</constant></entry> - <entry>Omitted for now</entry> - </row> - <row> - <entry><constant>V4L2_BUF_TYPE_EFFECTSIN</constant></entry> - <entry>Omitted for now</entry> - </row> - <row> - <entry><constant>V4L2_BUF_TYPE_EFFECTSIN2</constant></entry> - <entry>Omitted for now</entry> - </row> - <row> - <entry><constant>V4L2_BUF_TYPE_EFFECTSOUT</constant></entry> - <entry>Omitted for now</entry> - </row> - <row> - <entry><constant>V4L2_BUF_TYPE_VIDEOOUT</constant></entry> - <entry><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT</constant></entry> - </row> - <row> - <entry><constant>-</constant></entry> - <entry><constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant></entry> - </row> - <row> - <entry><constant>-</constant></entry> - <entry><constant>V4L2_BUF_TYPE_VBI_CAPTURE</constant></entry> - </row> - <row> - <entry><constant>-</constant></entry> - <entry><constant>V4L2_BUF_TYPE_VBI_OUTPUT</constant></entry> - </row> - <row> - <entry><constant>-</constant></entry> - <entry><constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant></entry> - </row> - <row> - <entry><constant>-</constant></entry> - <entry><constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant></entry> - </row> - <row> - <entry><constant>V4L2_BUF_TYPE_PRIVATE_BASE</constant></entry> - <entry><constant>V4L2_BUF_TYPE_PRIVATE</constant></entry> - </row> - </tbody> - </tgroup> - </informaltable></para> - </listitem> - - <listitem> - <para>In &v4l2-fmtdesc; a &v4l2-buf-type; field named -<structfield>type</structfield> was added as in &v4l2-format;. The -<constant>VIDIOC_ENUM_FBUFFMT</constant> ioctl is no longer needed and -was removed. These calls can be replaced by &VIDIOC-ENUM-FMT; with -type <constant>V4L2_BUF_TYPE_VIDEO_OVERLAY</constant>.</para> - </listitem> - - <listitem> - <para>In &v4l2-pix-format; the -<structfield>depth</structfield> field was removed, assuming -applications which recognize the format by its four-character-code -already know the color depth, and others do not care about it. The -same rationale lead to the removal of the -<constant>V4L2_FMT_FLAG_COMPRESSED</constant> flag. The -<constant>V4L2_FMT_FLAG_SWCONVECOMPRESSED</constant> flag was removed -because drivers are not supposed to convert images in kernel space. A -user library of conversion functions should be provided instead. The -<constant>V4L2_FMT_FLAG_BYTESPERLINE</constant> flag was redundant. -Applications can set the <structfield>bytesperline</structfield> field -to zero to get a reasonable default. Since the remaining flags were -replaced as well, the <structfield>flags</structfield> field itself -was removed.</para> - <para>The interlace flags were replaced by a &v4l2-field; -value in a newly added <structfield>field</structfield> -field.<informaltable> - <tgroup cols="2"> - <thead> - <row> - <entry>Old flag</entry> - <entry>&v4l2-field;</entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry><constant>V4L2_FMT_FLAG_NOT_INTERLACED</constant></entry> - <entry>?</entry> - </row> - <row> - <entry><constant>V4L2_FMT_FLAG_INTERLACED</constant> -= <constant>V4L2_FMT_FLAG_COMBINED</constant></entry> - <entry><constant>V4L2_FIELD_INTERLACED</constant></entry> - </row> - <row> - <entry><constant>V4L2_FMT_FLAG_TOPFIELD</constant> -= <constant>V4L2_FMT_FLAG_ODDFIELD</constant></entry> - <entry><constant>V4L2_FIELD_TOP</constant></entry> - </row> - <row> - <entry><constant>V4L2_FMT_FLAG_BOTFIELD</constant> -= <constant>V4L2_FMT_FLAG_EVENFIELD</constant></entry> - <entry><constant>V4L2_FIELD_BOTTOM</constant></entry> - </row> - <row> - <entry><constant>-</constant></entry> - <entry><constant>V4L2_FIELD_SEQ_TB</constant></entry> - </row> - <row> - <entry><constant>-</constant></entry> - <entry><constant>V4L2_FIELD_SEQ_BT</constant></entry> - </row> - <row> - <entry><constant>-</constant></entry> - <entry><constant>V4L2_FIELD_ALTERNATE</constant></entry> - </row> - </tbody> - </tgroup> - </informaltable></para> - - <para>The color space flags were replaced by a -&v4l2-colorspace; value in a newly added -<structfield>colorspace</structfield> field, where one of -<constant>V4L2_COLORSPACE_SMPTE170M</constant>, -<constant>V4L2_COLORSPACE_BT878</constant>, -<constant>V4L2_COLORSPACE_470_SYSTEM_M</constant> or -<constant>V4L2_COLORSPACE_470_SYSTEM_BG</constant> replaces -<constant>V4L2_FMT_CS_601YUV</constant>.</para> - </listitem> - - <listitem> - <para>In &v4l2-requestbuffers; the -<structfield>type</structfield> field was properly defined as -&v4l2-buf-type;. Buffer types changed as mentioned above. A new -<structfield>memory</structfield> field of type &v4l2-memory; was -added to distinguish between I/O methods using buffers allocated -by the driver or the application. See <xref linkend="io" /> for -details.</para> - </listitem> - - <listitem> - <para>In &v4l2-buffer; the <structfield>type</structfield> -field was properly defined as &v4l2-buf-type;. Buffer types changed as -mentioned above. A <structfield>field</structfield> field of type -&v4l2-field; was added to indicate if a buffer contains a top or -bottom field. The old field flags were removed. Since no unadjusted -system time clock was added to the kernel as planned, the -<structfield>timestamp</structfield> field changed back from type -stamp_t, an unsigned 64 bit integer expressing the sample time in -nanoseconds, to struct <structname>timeval</structname>. With the -addition of a second memory mapping method the -<structfield>offset</structfield> field moved into union -<structfield>m</structfield>, and a new -<structfield>memory</structfield> field of type &v4l2-memory; was -added to distinguish between I/O methods. See <xref linkend="io" /> -for details.</para> - - <para>The <constant>V4L2_BUF_REQ_CONTIG</constant> -flag was used by the V4L compatibility layer, after changes to this -code it was no longer needed. The -<constant>V4L2_BUF_ATTR_DEVICEMEM</constant> flag would indicate if -the buffer was indeed allocated in device memory rather than DMA-able -system memory. It was barely useful and so was removed.</para> - </listitem> - - <listitem> - <para>In &v4l2-framebuffer; the -<structfield>base[3]</structfield> array anticipating double- and -triple-buffering in off-screen video memory, however without defining -a synchronization mechanism, was replaced by a single pointer. The -<constant>V4L2_FBUF_CAP_SCALEUP</constant> and -<constant>V4L2_FBUF_CAP_SCALEDOWN</constant> flags were removed. -Applications can determine this capability more accurately using the -new cropping and scaling interface. The -<constant>V4L2_FBUF_CAP_CLIPPING</constant> flag was replaced by -<constant>V4L2_FBUF_CAP_LIST_CLIPPING</constant> and -<constant>V4L2_FBUF_CAP_BITMAP_CLIPPING</constant>.</para> - </listitem> - - <listitem> - <para>In &v4l2-clip; the <structfield>x</structfield>, -<structfield>y</structfield>, <structfield>width</structfield> and -<structfield>height</structfield> field moved into a -<structfield>c</structfield> substructure of type &v4l2-rect;. The -<structfield>x</structfield> and <structfield>y</structfield> fields -were renamed to <structfield>left</structfield> and -<structfield>top</structfield>, &ie; offsets to a context dependent -origin.</para> - </listitem> - - <listitem> - <para>In &v4l2-window; the <structfield>x</structfield>, -<structfield>y</structfield>, <structfield>width</structfield> and -<structfield>height</structfield> field moved into a -<structfield>w</structfield> substructure as above. A -<structfield>field</structfield> field of type %v4l2-field; was added -to distinguish between field and frame (interlaced) overlay.</para> - </listitem> - - <listitem> - <para>The digital zoom interface, including struct -<structname>v4l2_zoomcap</structname>, struct -<structname>v4l2_zoom</structname>, -<constant>V4L2_ZOOM_NONCAP</constant> and -<constant>V4L2_ZOOM_WHILESTREAMING</constant> was replaced by a new -cropping and scaling interface. The previously unused struct -<structname>v4l2_cropcap</structname> and -<structname>v4l2_crop</structname> where redefined for this purpose. -See <xref linkend="crop" /> for details.</para> - </listitem> - - <listitem> - <para>In &v4l2-vbi-format; the -<structfield>SAMPLE_FORMAT</structfield> field now contains a -four-character-code as used to identify video image formats and -<constant>V4L2_PIX_FMT_GREY</constant> replaces the -<constant>V4L2_VBI_SF_UBYTE</constant> define. The -<structfield>reserved</structfield> field was extended.</para> - </listitem> - - <listitem> - <para>In &v4l2-captureparm; the type of the -<structfield>timeperframe</structfield> field changed from unsigned -long to &v4l2-fract;. This allows the accurate expression of multiples -of the NTSC-M frame rate 30000 / 1001. A new field -<structfield>readbuffers</structfield> was added to control the driver -behaviour in read I/O mode.</para> - - <para>Similar changes were made to &v4l2-outputparm;.</para> - </listitem> - - <listitem> - <para>The struct <structname>v4l2_performance</structname> -and <constant>VIDIOC_G_PERF</constant> ioctl were dropped. Except when -using the <link linkend="rw">read/write I/O method</link>, which is -limited anyway, this information is already available to -applications.</para> - </listitem> - - <listitem> - <para>The example transformation from RGB to YCbCr color -space in the old V4L2 documentation was inaccurate, this has been -corrected in <xref linkend="pixfmt" />.<!-- 0.5670G should be -0.587, and 127/112 != 255/224 --></para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 2003-06-19</title> - - <orderedlist> - <listitem> - <para>A new capability flag -<constant>V4L2_CAP_RADIO</constant> was added for radio devices. Prior -to this change radio devices would identify solely by having exactly one -tuner whose type field reads <constant>V4L2_TUNER_RADIO</constant>.</para> - </listitem> - - <listitem> - <para>An optional driver access priority mechanism was -added, see <xref linkend="app-pri" /> for details.</para> - </listitem> - - <listitem> - <para>The audio input and output interface was found to be -incomplete.</para> - <para>Previously the &VIDIOC-G-AUDIO; -ioctl would enumerate the available audio inputs. An ioctl to -determine the current audio input, if more than one combines with the -current video input, did not exist. So -<constant>VIDIOC_G_AUDIO</constant> was renamed to -<constant>VIDIOC_G_AUDIO_OLD</constant>, this ioctl was removed on -Kernel 2.6.39. The &VIDIOC-ENUMAUDIO; ioctl was added to enumerate -audio inputs, while &VIDIOC-G-AUDIO; now reports the current audio -input.</para> - <para>The same changes were made to &VIDIOC-G-AUDOUT; and -&VIDIOC-ENUMAUDOUT;.</para> - <para>Until further the "videodev" module will automatically -translate between the old and new ioctls, but drivers and applications -must be updated to successfully compile again.</para> - </listitem> - - <listitem> - <para>The &VIDIOC-OVERLAY; ioctl was incorrectly defined with -write-read parameter. It was changed to write-only, while the write-read -version was renamed to <constant>VIDIOC_OVERLAY_OLD</constant>. The old -ioctl was removed on Kernel 2.6.39. Until further the "videodev" -kernel module will automatically translate to the new version, so drivers -must be recompiled, but not applications.</para> - </listitem> - - <listitem> - <para><xref linkend="overlay" /> incorrectly stated that -clipping rectangles define regions where the video can be seen. -Correct is that clipping rectangles define regions where -<emphasis>no</emphasis> video shall be displayed and so the graphics -surface can be seen.</para> - </listitem> - - <listitem> - <para>The &VIDIOC-S-PARM; and &VIDIOC-S-CTRL; ioctls were -defined with write-only parameter, inconsistent with other ioctls -modifying their argument. They were changed to write-read, while a -<constant>_OLD</constant> suffix was added to the write-only versions. -The old ioctls were removed on Kernel 2.6.39. Drivers and -applications assuming a constant parameter need an update.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 2003-11-05</title> - <orderedlist> - <listitem> - <para>In <xref linkend="pixfmt-rgb" /> the following pixel -formats were incorrectly transferred from Bill Dirks' V4L2 -specification. Descriptions below refer to bytes in memory, in -ascending address order.<informaltable> - <tgroup cols="3"> - <thead> - <row> - <entry>Symbol</entry> - <entry>In this document prior to revision -0.5</entry> - <entry>Corrected</entry> - </row> - </thead> - <tbody valign="top"> - <row> - <entry><constant>V4L2_PIX_FMT_RGB24</constant></entry> - <entry>B, G, R</entry> - <entry>R, G, B</entry> - </row> - <row> - <entry><constant>V4L2_PIX_FMT_BGR24</constant></entry> - <entry>R, G, B</entry> - <entry>B, G, R</entry> - </row> - <row> - <entry><constant>V4L2_PIX_FMT_RGB32</constant></entry> - <entry>B, G, R, X</entry> - <entry>R, G, B, X</entry> - </row> - <row> - <entry><constant>V4L2_PIX_FMT_BGR32</constant></entry> - <entry>R, G, B, X</entry> - <entry>B, G, R, X</entry> - </row> - </tbody> - </tgroup> - </informaltable> The -<constant>V4L2_PIX_FMT_BGR24</constant> example was always -correct.</para> - <para>In <xref linkend="v4l-image-properties" /> the mapping -of the V4L <constant>VIDEO_PALETTE_RGB24</constant> and -<constant>VIDEO_PALETTE_RGB32</constant> formats to V4L2 pixel formats -was accordingly corrected.</para> - </listitem> - - <listitem> - <para>Unrelated to the fixes above, drivers may still -interpret some V4L2 RGB pixel formats differently. These issues have -yet to be addressed, for details see <xref - linkend="pixfmt-rgb" />.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.6, 2004-05-09</title> - <orderedlist> - <listitem> - <para>The &VIDIOC-CROPCAP; ioctl was incorrectly defined -with read-only parameter. It is now defined as write-read ioctl, while -the read-only version was renamed to -<constant>VIDIOC_CROPCAP_OLD</constant>. The old ioctl was removed -on Kernel 2.6.39.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.8</title> - <orderedlist> - <listitem> - <para>A new field <structfield>input</structfield> (former -<structfield>reserved[0]</structfield>) was added to the &v4l2-buffer; -structure. Purpose of this field is to alternate between video inputs -(⪚ cameras) in step with the video capturing process. This function -must be enabled with the new <constant>V4L2_BUF_FLAG_INPUT</constant> -flag. The <structfield>flags</structfield> field is no longer -read-only.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 spec erratum 2004-08-01</title> - - <orderedlist> - <listitem> - <para>The return value of the -<xref linkend="func-open" /> function was incorrectly documented.</para> - </listitem> - - <listitem> - <para>Audio output ioctls end in -AUDOUT, not -AUDIOOUT.</para> - </listitem> - - <listitem> - <para>In the Current Audio Input example the -<constant>VIDIOC_G_AUDIO</constant> ioctl took the wrong -argument.</para> - </listitem> - - <listitem> - <para>The documentation of the &VIDIOC-QBUF; and -&VIDIOC-DQBUF; ioctls did not mention the &v4l2-buffer; -<structfield>memory</structfield> field. It was also missing from -examples. Also on the <constant>VIDIOC_DQBUF</constant> page the &EIO; -was not documented.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.14</title> - <orderedlist> - <listitem> - <para>A new sliced VBI interface was added. It is documented -in <xref linkend="sliced" /> and replaces the interface first -proposed in V4L2 specification 0.8.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.15</title> - <orderedlist> - <listitem> - <para>The &VIDIOC-LOG-STATUS; ioctl was added.</para> - </listitem> - - <listitem> - <para>New video standards -<constant>V4L2_STD_NTSC_443</constant>, -<constant>V4L2_STD_SECAM_LC</constant>, -<constant>V4L2_STD_SECAM_DK</constant> (a set of SECAM D, K and K1), -and <constant>V4L2_STD_ATSC</constant> (a set of -<constant>V4L2_STD_ATSC_8_VSB</constant> and -<constant>V4L2_STD_ATSC_16_VSB</constant>) were defined. Note the -<constant>V4L2_STD_525_60</constant> set now includes -<constant>V4L2_STD_NTSC_443</constant>. See also <xref - linkend="v4l2-std-id" />.</para> - </listitem> - - <listitem> - <para>The <constant>VIDIOC_G_COMP</constant> and -<constant>VIDIOC_S_COMP</constant> ioctl were renamed to -<constant>VIDIOC_G_MPEGCOMP</constant> and -<constant>VIDIOC_S_MPEGCOMP</constant> respectively. Their argument -was replaced by a struct -<structname>v4l2_mpeg_compression</structname> pointer. (The -<constant>VIDIOC_G_MPEGCOMP</constant> and -<constant>VIDIOC_S_MPEGCOMP</constant> ioctls where removed in Linux -2.6.25.)</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 spec erratum 2005-11-27</title> - <para>The capture example in <xref linkend="capture-example" /> -called the &VIDIOC-S-CROP; ioctl without checking if cropping is -supported. In the video standard selection example in -<xref linkend="standard" /> the &VIDIOC-S-STD; call used the wrong -argument type.</para> - </section> - - <section> - <title>V4L2 spec erratum 2006-01-10</title> - <orderedlist> - <listitem> - <para>The <constant>V4L2_IN_ST_COLOR_KILL</constant> flag in -&v4l2-input; not only indicates if the color killer is enabled, but -also if it is active. (The color killer disables color decoding when -it detects no color in the video signal to improve the image -quality.)</para> - </listitem> - - <listitem> - <para>&VIDIOC-S-PARM; is a write-read ioctl, not write-only as -stated on its reference page. The ioctl changed in 2003 as noted above.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 spec erratum 2006-02-03</title> - <orderedlist> - <listitem> - <para>In &v4l2-captureparm; and &v4l2-outputparm; the -<structfield>timeperframe</structfield> field gives the time in -seconds, not microseconds.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 spec erratum 2006-02-04</title> - <orderedlist> - <listitem> - <para>The <structfield>clips</structfield> field in -&v4l2-window; must point to an array of &v4l2-clip;, not a linked -list, because drivers ignore the struct -<structname>v4l2_clip</structname>.<structfield>next</structfield> -pointer.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.17</title> - <orderedlist> - <listitem> - <para>New video standard macros were added: -<constant>V4L2_STD_NTSC_M_KR</constant> (NTSC M South Korea), and the -sets <constant>V4L2_STD_MN</constant>, -<constant>V4L2_STD_B</constant>, <constant>V4L2_STD_GH</constant> and -<constant>V4L2_STD_DK</constant>. The -<constant>V4L2_STD_NTSC</constant> and -<constant>V4L2_STD_SECAM</constant> sets now include -<constant>V4L2_STD_NTSC_M_KR</constant> and -<constant>V4L2_STD_SECAM_LC</constant> respectively.</para> - </listitem> - - <listitem> - <para>A new <constant>V4L2_TUNER_MODE_LANG1_LANG2</constant> -was defined to record both languages of a bilingual program. The -use of <constant>V4L2_TUNER_MODE_STEREO</constant> for this purpose -is deprecated now. See the &VIDIOC-G-TUNER; section for -details.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 spec erratum 2006-09-23 (Draft 0.15)</title> - <orderedlist> - <listitem> - <para>In various places -<constant>V4L2_BUF_TYPE_SLICED_VBI_CAPTURE</constant> and -<constant>V4L2_BUF_TYPE_SLICED_VBI_OUTPUT</constant> of the sliced VBI -interface were not mentioned along with other buffer types.</para> - </listitem> - - <listitem> - <para>In <xref linkend="vidioc-g-audio" /> it was clarified -that the &v4l2-audio; <structfield>mode</structfield> field is a flags -field.</para> - </listitem> - - <listitem> - <para><xref linkend="vidioc-querycap" /> did not mention the -sliced VBI and radio capability flags.</para> - </listitem> - - <listitem> - <para>In <xref linkend="vidioc-g-frequency" /> it was -clarified that applications must initialize the tuner -<structfield>type</structfield> field of &v4l2-frequency; before -calling &VIDIOC-S-FREQUENCY;.</para> - </listitem> - - <listitem> - <para>The <structfield>reserved</structfield> array -in &v4l2-requestbuffers; has 2 elements, not 32.</para> - </listitem> - - <listitem> - <para>In <xref linkend="output" /> and <xref - linkend="raw-vbi" /> the device file names -<filename>/dev/vout</filename> which never caught on were replaced -by <filename>/dev/video</filename>.</para> - </listitem> - - <listitem> - <para>With Linux 2.6.15 the possible range for VBI device minor -numbers was extended from 224-239 to 224-255. Accordingly device file names -<filename>/dev/vbi0</filename> to <filename>/dev/vbi31</filename> are -possible now.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.18</title> - <orderedlist> - <listitem> - <para>New ioctls &VIDIOC-G-EXT-CTRLS;, &VIDIOC-S-EXT-CTRLS; -and &VIDIOC-TRY-EXT-CTRLS; were added, a flag to skip unsupported -controls with &VIDIOC-QUERYCTRL;, new control types -<constant>V4L2_CTRL_TYPE_INTEGER64</constant> and -<constant>V4L2_CTRL_TYPE_CTRL_CLASS</constant> (<xref - linkend="v4l2-ctrl-type" />), and new control flags -<constant>V4L2_CTRL_FLAG_READ_ONLY</constant>, -<constant>V4L2_CTRL_FLAG_UPDATE</constant>, -<constant>V4L2_CTRL_FLAG_INACTIVE</constant> and -<constant>V4L2_CTRL_FLAG_SLIDER</constant> (<xref - linkend="control-flags" />). See <xref - linkend="extended-controls" /> for details.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.19</title> - <orderedlist> - <listitem> - <para>In &v4l2-sliced-vbi-cap; a buffer type field was added -replacing a reserved field. Note on architectures where the size of -enum types differs from int types the size of the structure changed. -The &VIDIOC-G-SLICED-VBI-CAP; ioctl was redefined from being read-only -to write-read. Applications must initialize the type field and clear -the reserved fields now. These changes may <emphasis>break the -compatibility</emphasis> with older drivers and applications.</para> - </listitem> - - <listitem> - <para>The ioctls &VIDIOC-ENUM-FRAMESIZES; and -&VIDIOC-ENUM-FRAMEINTERVALS; were added.</para> - </listitem> - - <listitem> - <para>A new pixel format <constant>V4L2_PIX_FMT_RGB444</constant> (<xref -linkend="rgb-formats" />) was added.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 spec erratum 2006-10-12 (Draft 0.17)</title> - <orderedlist> - <listitem> - <para><constant>V4L2_PIX_FMT_HM12</constant> (<xref -linkend="reserved-formats" />) is a YUV 4:2:0, not 4:2:2 format.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.21</title> - <orderedlist> - <listitem> - <para>The <filename>videodev2.h</filename> header file is -now dual licensed under GNU General Public License version two or -later, and under a 3-clause BSD-style license.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.22</title> - <orderedlist> - <listitem> - <para>Two new field orders - <constant>V4L2_FIELD_INTERLACED_TB</constant> and - <constant>V4L2_FIELD_INTERLACED_BT</constant> were - added. See <xref linkend="v4l2-field" /> for details.</para> - </listitem> - - <listitem> - <para>Three new clipping/blending methods with a global or -straight or inverted local alpha value were added to the video overlay -interface. See the description of the &VIDIOC-G-FBUF; and -&VIDIOC-S-FBUF; ioctls for details.</para> - <para>A new <structfield>global_alpha</structfield> field -was added to <link -linkend="v4l2-window"><structname>v4l2_window</structname></link>, -extending the structure. This may <emphasis>break -compatibility</emphasis> with applications using a struct -<structname>v4l2_window</structname> directly. However the <link -linkend="vidioc-g-fmt">VIDIOC_G/S/TRY_FMT</link> ioctls, which take a -pointer to a <link linkend="v4l2-format">v4l2_format</link> parent -structure with padding bytes at the end, are not affected.</para> - </listitem> - - <listitem> - <para>The format of the <structfield>chromakey</structfield> -field in &v4l2-window; changed from "host order RGB32" to a pixel -value in the same format as the framebuffer. This may <emphasis>break -compatibility</emphasis> with existing applications. Drivers -supporting the "host order RGB32" format are not known.</para> - </listitem> - - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.24</title> - <orderedlist> - <listitem> - <para>The pixel formats -<constant>V4L2_PIX_FMT_PAL8</constant>, -<constant>V4L2_PIX_FMT_YUV444</constant>, -<constant>V4L2_PIX_FMT_YUV555</constant>, -<constant>V4L2_PIX_FMT_YUV565</constant> and -<constant>V4L2_PIX_FMT_YUV32</constant> were added.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.25</title> - <orderedlist> - <listitem> - <para>The pixel formats <link linkend="V4L2-PIX-FMT-Y16"> -<constant>V4L2_PIX_FMT_Y16</constant></link> and <link -linkend="V4L2-PIX-FMT-SBGGR16"> -<constant>V4L2_PIX_FMT_SBGGR16</constant></link> were added.</para> - </listitem> - <listitem> - <para>New <link linkend="control">controls</link> -<constant>V4L2_CID_POWER_LINE_FREQUENCY</constant>, -<constant>V4L2_CID_HUE_AUTO</constant>, -<constant>V4L2_CID_WHITE_BALANCE_TEMPERATURE</constant>, -<constant>V4L2_CID_SHARPNESS</constant> and -<constant>V4L2_CID_BACKLIGHT_COMPENSATION</constant> were added. The -controls <constant>V4L2_CID_BLACK_LEVEL</constant>, -<constant>V4L2_CID_WHITENESS</constant>, -<constant>V4L2_CID_HCENTER</constant> and -<constant>V4L2_CID_VCENTER</constant> were deprecated. -</para> - </listitem> - <listitem> - <para>A <link linkend="camera-controls">Camera controls -class</link> was added, with the new controls -<constant>V4L2_CID_EXPOSURE_AUTO</constant>, -<constant>V4L2_CID_EXPOSURE_ABSOLUTE</constant>, -<constant>V4L2_CID_EXPOSURE_AUTO_PRIORITY</constant>, -<constant>V4L2_CID_PAN_RELATIVE</constant>, -<constant>V4L2_CID_TILT_RELATIVE</constant>, -<constant>V4L2_CID_PAN_RESET</constant>, -<constant>V4L2_CID_TILT_RESET</constant>, -<constant>V4L2_CID_PAN_ABSOLUTE</constant>, -<constant>V4L2_CID_TILT_ABSOLUTE</constant>, -<constant>V4L2_CID_FOCUS_ABSOLUTE</constant>, -<constant>V4L2_CID_FOCUS_RELATIVE</constant> and -<constant>V4L2_CID_FOCUS_AUTO</constant>.</para> - </listitem> - <listitem> - <para>The <constant>VIDIOC_G_MPEGCOMP</constant> and -<constant>VIDIOC_S_MPEGCOMP</constant> ioctls, which were superseded -by the <link linkend="extended-controls">extended controls</link> -interface in Linux 2.6.18, where finally removed from the -<filename>videodev2.h</filename> header file.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.26</title> - <orderedlist> - <listitem> - <para>The pixel formats -<constant>V4L2_PIX_FMT_Y16</constant> and -<constant>V4L2_PIX_FMT_SBGGR16</constant> were added.</para> - </listitem> - <listitem> - <para>Added user controls -<constant>V4L2_CID_CHROMA_AGC</constant> and -<constant>V4L2_CID_COLOR_KILLER</constant>.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.27</title> - <orderedlist> - <listitem> - <para>The &VIDIOC-S-HW-FREQ-SEEK; ioctl and the -<constant>V4L2_CAP_HW_FREQ_SEEK</constant> capability were added.</para> - </listitem> - <listitem> - <para>The pixel formats -<constant>V4L2_PIX_FMT_YVYU</constant>, -<constant>V4L2_PIX_FMT_PCA501</constant>, -<constant>V4L2_PIX_FMT_PCA505</constant>, -<constant>V4L2_PIX_FMT_PCA508</constant>, -<constant>V4L2_PIX_FMT_PCA561</constant>, -<constant>V4L2_PIX_FMT_SGBRG8</constant>, -<constant>V4L2_PIX_FMT_PAC207</constant> and -<constant>V4L2_PIX_FMT_PJPG</constant> were added.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.28</title> - <orderedlist> - <listitem> - <para>Added <constant>V4L2_MPEG_AUDIO_ENCODING_AAC</constant> and -<constant>V4L2_MPEG_AUDIO_ENCODING_AC3</constant> MPEG audio encodings.</para> - </listitem> - <listitem> - <para>Added <constant>V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC</constant> MPEG -video encoding.</para> - </listitem> - <listitem> - <para>The pixel formats -<constant>V4L2_PIX_FMT_SGRBG10</constant> and -<constant>V4L2_PIX_FMT_SGRBG10DPCM8</constant> were added.</para> - </listitem> - </orderedlist> - </section> - - <section> - <title>V4L2 in Linux 2.6.29</title> - <orderedlist> - <listitem> - <para>The <constant>VIDIOC_G_CHIP_IDENT</constant> ioctl was renamed -to <constant>VIDIOC_G_CHIP_IDENT_OLD</constant> and &VIDIOC-DBG-G-CHIP-IDENT; -was introduced in its place. The old struct <structname>v4l2_chip_ident</structname> -was renamed to <structname id="v4l2-chip-ident-old">v4l2_chip_ident_old</structname>.</para> - </listitem> - <listitem> - <para>The pixel formats -<constant>V4L2_PIX_FMT_VYUY</constant>, -<constant>V4L2_PIX_FMT_NV16</constant> and -<constant>V4L2_PIX_FMT_NV61</constant> were added.</para> - </listitem> - <listitem> - <para>Added camera controls -<constant>V4L2_CID_ZOOM_ABSOLUTE</constant>, -<constant>V4L2_CID_ZOOM_RELATIVE</constant>, -<constant>V4L2_CID_ZOOM_CONTINUOUS</constant> and -<constant>V4L2_CID_PRIVACY</constant>.</para> - </listitem> - </orderedlist> - </section> - <section> - <title>V4L2 in Linux 2.6.30</title> - <orderedlist> - <listitem> - <para>New control flag <constant>V4L2_CTRL_FLAG_WRITE_ONLY</constant> was added.</para> - </listitem> - <listitem> - <para>New control <constant>V4L2_CID_COLORFX</constant> was added.</para> - </listitem> - </orderedlist> - </section> - <section> - <title>V4L2 in Linux 2.6.32</title> - <orderedlist> - <listitem> - <para>In order to be easier to compare a V4L2 API and a kernel -version, now V4L2 API is numbered using the Linux Kernel version numeration.</para> - </listitem> - <listitem> - <para>Finalized the RDS capture API. See <xref linkend="rds" /> for -more information.</para> - </listitem> - <listitem> - <para>Added new capabilities for modulators and RDS encoders.</para> - </listitem> - <listitem> - <para>Add description for libv4l API.</para> - </listitem> - <listitem> - <para>Added support for string controls via new type <constant>V4L2_CTRL_TYPE_STRING</constant>.</para> - </listitem> - <listitem> - <para>Added <constant>V4L2_CID_BAND_STOP_FILTER</constant> documentation.</para> - </listitem> - <listitem> - <para>Added FM Modulator (FM TX) Extended Control Class: <constant>V4L2_CTRL_CLASS_FM_TX</constant> and their Control IDs.</para> - </listitem> - <listitem> - <para>Added Remote Controller chapter, describing the default Remote Controller mapping for media devices.</para> - </listitem> - </orderedlist> - </section> - <section> - <title>V4L2 in Linux 2.6.33</title> - <orderedlist> - <listitem> - <para>Added support for Digital Video timings in order to support HDTV receivers and transmitters.</para> - </listitem> - </orderedlist> - </section> - <section> - <title>V4L2 in Linux 2.6.34</title> - <orderedlist> - <listitem> - <para>Added -<constant>V4L2_CID_IRIS_ABSOLUTE</constant> and -<constant>V4L2_CID_IRIS_RELATIVE</constant> controls to the - <link linkend="camera-controls">Camera controls class</link>. - </para> - </listitem> - </orderedlist> - </section> - <section> - <title>V4L2 in Linux 2.6.37</title> - <orderedlist> - <listitem> - <para>Remove the vtx (videotext/teletext) API. This API was no longer -used and no hardware exists to verify the API. Nor were any userspace applications found -that used it. It was originally scheduled for removal in 2.6.35. - </para> - </listitem> - </orderedlist> - </section> - <section> - <title>V4L2 in Linux 2.6.39</title> - <orderedlist> - <listitem> - <para>The old VIDIOC_*_OLD symbols and V4L1 support were removed.</para> - </listitem> - <listitem> - <para>Multi-planar API added. Does not affect the compatibility of - current drivers and applications. See - <link linkend="planar-apis">multi-planar API</link> - for details.</para> - </listitem> - </orderedlist> - </section> - - <section id="other"> - <title>Relation of V4L2 to other Linux multimedia APIs</title> - - <section id="xvideo"> - <title>X Video Extension</title> - - <para>The X Video Extension (abbreviated XVideo or just Xv) is -an extension of the X Window system, implemented for example by the -XFree86 project. Its scope is similar to V4L2, an API to video capture -and output devices for X clients. Xv allows applications to display -live video in a window, send window contents to a TV output, and -capture or output still images in XPixmaps<footnote> - <para>This is not implemented in XFree86.</para> - </footnote>. With their implementation XFree86 makes the -extension available across many operating systems and -architectures.</para> - - <para>Because the driver is embedded into the X server Xv has a -number of advantages over the V4L2 <link linkend="overlay">video -overlay interface</link>. The driver can easily determine the overlay -target, &ie; visible graphics memory or off-screen buffers for a -destructive overlay. It can program the RAMDAC for a non-destructive -overlay, scaling or color-keying, or the clipping functions of the -video capture hardware, always in sync with drawing operations or -windows moving or changing their stacking order.</para> - - <para>To combine the advantages of Xv and V4L a special Xv -driver exists in XFree86 and XOrg, just programming any overlay capable -Video4Linux device it finds. To enable it -<filename>/etc/X11/XF86Config</filename> must contain these lines:</para> - <para><screen> -Section "Module" - Load "v4l" -EndSection</screen></para> - - <para>As of XFree86 4.2 this driver still supports only V4L -ioctls, however it should work just fine with all V4L2 devices through -the V4L2 backward-compatibility layer. Since V4L2 permits multiple -opens it is possible (if supported by the V4L2 driver) to capture -video while an X client requested video overlay. Restrictions of -simultaneous capturing and overlay are discussed in <xref - linkend="overlay" /> apply.</para> - - <para>Only marginally related to V4L2, XFree86 extended Xv to -support hardware YUV to RGB conversion and scaling for faster video -playback, and added an interface to MPEG-2 decoding hardware. This API -is useful to display images captured with V4L2 devices.</para> - </section> - - <section> - <title>Digital Video</title> - - <para>V4L2 does not support digital terrestrial, cable or -satellite broadcast. A separate project aiming at digital receivers -exists. You can find its homepage at <ulink -url="http://linuxtv.org">http://linuxtv.org</ulink>. The Linux DVB API -has no connection to the V4L2 API except that drivers for hybrid -hardware may support both.</para> - </section> - - <section> - <title>Audio Interfaces</title> - - <para>[to do - OSS/ALSA]</para> - </section> - </section> - - <section id="experimental"> - <title>Experimental API Elements</title> - - <para>The following V4L2 API elements are currently experimental -and may change in the future.</para> - - <itemizedlist> - <listitem> - <para>Video Output Overlay (OSD) Interface, <xref - linkend="osd" />.</para> - </listitem> - <listitem> - <para><constant>V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY</constant>, - &v4l2-buf-type;, <xref linkend="v4l2-buf-type" />.</para> - </listitem> - <listitem> - <para><constant>V4L2_CAP_VIDEO_OUTPUT_OVERLAY</constant>, -&VIDIOC-QUERYCAP; ioctl, <xref linkend="device-capabilities" />.</para> - </listitem> - <listitem> - <para>&VIDIOC-ENUM-FRAMESIZES; and -&VIDIOC-ENUM-FRAMEINTERVALS; ioctls.</para> - </listitem> - <listitem> - <para>&VIDIOC-G-ENC-INDEX; ioctl.</para> - </listitem> - <listitem> - <para>&VIDIOC-ENCODER-CMD; and &VIDIOC-TRY-ENCODER-CMD; -ioctls.</para> - </listitem> - <listitem> - <para>&VIDIOC-DBG-G-REGISTER; and &VIDIOC-DBG-S-REGISTER; -ioctls.</para> - </listitem> - <listitem> - <para>&VIDIOC-DBG-G-CHIP-IDENT; ioctl.</para> - </listitem> - </itemizedlist> - </section> - - <section id="obsolete"> - <title>Obsolete API Elements</title> - - <para>The following V4L2 API elements were superseded by new -interfaces and should not be implemented in new drivers.</para> - - <itemizedlist> - <listitem> - <para><constant>VIDIOC_G_MPEGCOMP</constant> and -<constant>VIDIOC_S_MPEGCOMP</constant> ioctls. Use Extended Controls, -<xref linkend="extended-controls" />.</para> - </listitem> - </itemizedlist> - </section> - </section> - - <!-- -Local Variables: -mode: sgml -sgml-parent-document: "v4l2.sgml" -indent-tabs-mode: nil -End: - --> |
