diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/DocBook/media-entities.tmpl | 4 | ||||
| -rw-r--r-- | Documentation/DocBook/v4l/dev-subdev.xml | 33 | ||||
| -rw-r--r-- | Documentation/DocBook/v4l/v4l2.xml | 1 | ||||
| -rw-r--r-- | Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml | 155 |
4 files changed, 193 insertions, 0 deletions
diff --git a/Documentation/DocBook/media-entities.tmpl b/Documentation/DocBook/media-entities.tmpl index a95eb57..40158ee 100644 --- a/Documentation/DocBook/media-entities.tmpl +++ b/Documentation/DocBook/media-entities.tmpl @@ -88,8 +88,10 @@ <!ENTITY VIDIOC-S-TUNER "<link linkend='vidioc-g-tuner'><constant>VIDIOC_S_TUNER</constant></link>"> <!ENTITY VIDIOC-SUBDEV-ENUM-FRAME-SIZE "<link linkend='vidioc-subdev-enum-frame-size'><constant>VIDIOC_SUBDEV_ENUM_FRAME_SIZE</constant></link>"> <!ENTITY VIDIOC-SUBDEV-ENUM-MBUS-CODE "<link linkend='vidioc-subdev-enum-mbus-code'><constant>VIDIOC_SUBDEV_ENUM_MBUS_CODE</constant></link>"> +<!ENTITY VIDIOC-SUBDEV-G-CROP "<link linkend='vidioc-subdev-g-crop'><constant>VIDIOC_SUBDEV_G_CROP</constant></link>"> <!ENTITY VIDIOC-SUBDEV-G-FMT "<link linkend='vidioc-subdev-g-fmt'><constant>VIDIOC_SUBDEV_G_FMT</constant></link>"> <!ENTITY VIDIOC-SUBDEV-G-FRAME-INTERVAL "<link linkend='vidioc-subdev-g-frame-interval'><constant>VIDIOC_SUBDEV_G_FRAME_INTERVAL</constant></link>"> +<!ENTITY VIDIOC-SUBDEV-S-CROP "<link linkend='vidioc-subdev-g-crop'><constant>VIDIOC_SUBDEV_S_CROP</constant></link>"> <!ENTITY VIDIOC-SUBDEV-S-FMT "<link linkend='vidioc-subdev-g-fmt'><constant>VIDIOC_SUBDEV_S_FMT</constant></link>"> <!ENTITY VIDIOC-SUBDEV-S-FRAME-INTERVAL "<link linkend='vidioc-subdev-g-frame-interval'><constant>VIDIOC_SUBDEV_S_FRAME_INTERVAL</constant></link>"> <!ENTITY VIDIOC-TRY-ENCODER-CMD "<link linkend='vidioc-encoder-cmd'><constant>VIDIOC_TRY_ENCODER_CMD</constant></link>"> @@ -198,6 +200,7 @@ <!ENTITY v4l2-subdev-frame-interval "struct <link linkend='v4l2-subdev-frame-interval'>v4l2_subdev_frame_interval</link>"> <!ENTITY v4l2-subdev-frame-interval-enum "struct <link linkend='v4l2-subdev-frame-interval-enum'>v4l2_subdev_frame_interval_enum</link>"> <!ENTITY v4l2-subdev-frame-size-enum "struct <link linkend='v4l2-subdev-frame-size-enum'>v4l2_subdev_frame_size_enum</link>"> +<!ENTITY v4l2-subdev-crop "struct <link linkend='v4l2-subdev-crop'>v4l2_subdev_crop</link>"> <!ENTITY v4l2-subdev-format "struct <link linkend='v4l2-subdev-format'>v4l2_subdev_format</link>"> <!ENTITY v4l2-subdev-mbus-code-enum "struct <link linkend='v4l2-subdev-mbus-code-enum'>v4l2_subdev_mbus_code_enum</link>"> <!ENTITY v4l2-standard "struct <link linkend='v4l2-standard'>v4l2_standard</link>"> @@ -339,6 +342,7 @@ <!ENTITY sub-subdev-enum-frame-size SYSTEM "v4l/vidioc-subdev-enum-frame-size.xml"> <!ENTITY sub-subdev-enum-mbus-code SYSTEM "v4l/vidioc-subdev-enum-mbus-code.xml"> <!ENTITY sub-subdev-formats SYSTEM "v4l/subdev-formats.xml"> +<!ENTITY sub-subdev-g-crop SYSTEM "v4l/vidioc-subdev-g-crop.xml"> <!ENTITY sub-subdev-g-fmt SYSTEM "v4l/vidioc-subdev-g-fmt.xml"> <!ENTITY sub-subdev-g-frame-interval SYSTEM "v4l/vidioc-subdev-g-frame-interval.xml"> <!ENTITY sub-capture-c SYSTEM "v4l/capture.c.xml"> diff --git a/Documentation/DocBook/v4l/dev-subdev.xml b/Documentation/DocBook/v4l/dev-subdev.xml index fc62e65..e9eb8af 100644 --- a/Documentation/DocBook/v4l/dev-subdev.xml +++ b/Documentation/DocBook/v4l/dev-subdev.xml @@ -275,6 +275,39 @@ </para> </section> + <section> + <title>Cropping and scaling</title> + + <para>Many sub-devices support cropping frames on their input or output + pads (or possible even on both). Cropping is used to select the area of + interest in an image, typically on a video sensor or video decoder. It can + also be used as part of digital zoom implementations to select the area of + the image that will be scaled up.</para> + + <para>Crop settings are defined by a crop rectangle and represented in a + &v4l2-rect; by the coordinates of the top left corner and the rectangle + size. Both the coordinates and sizes are expressed in pixels.</para> + + <para>The crop rectangle is retrieved and set using the + &VIDIOC-SUBDEV-G-CROP; and &VIDIOC-SUBDEV-S-CROP; ioctls. Like for pad + formats, drivers store try and active crop rectangles. The format + negotiation mechanism applies to crop settings as well.</para> + + <para>On input pads, cropping is applied relatively to the current pad + format. The pad format represents the image size as received by the + sub-device from the previous block in the pipeline, and the crop rectangle + represents the sub-image that will be transmitted further inside the + sub-device for processing. The crop rectangle be entirely containted + inside the input image size.</para> + + <para>Input crop rectangle are reset to their default value when the input + image format is modified. Drivers should use the input image size as the + crop rectangle default value, but hardware requirements may prevent this. + </para> + + <para>Cropping behaviour on output pads is not defined.</para> + + </section> </section> &sub-subdev-formats; diff --git a/Documentation/DocBook/v4l/v4l2.xml b/Documentation/DocBook/v4l/v4l2.xml index a436716..3a6e3b5 100644 --- a/Documentation/DocBook/v4l/v4l2.xml +++ b/Documentation/DocBook/v4l/v4l2.xml @@ -510,6 +510,7 @@ and discussions on the V4L mailing list.</revremark> &sub-subdev-enum-frame-interval; &sub-subdev-enum-frame-size; &sub-subdev-enum-mbus-code; + &sub-subdev-g-crop; &sub-subdev-g-fmt; &sub-subdev-g-frame-interval; &sub-subscribe-event; diff --git a/Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml b/Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml new file mode 100644 index 0000000..0619732 --- /dev/null +++ b/Documentation/DocBook/v4l/vidioc-subdev-g-crop.xml @@ -0,0 +1,155 @@ +<refentry id="vidioc-subdev-g-crop"> + <refmeta> + <refentrytitle>ioctl VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_SUBDEV_G_CROP</refname> + <refname>VIDIOC_SUBDEV_S_CROP</refname> + <refpurpose>Get or set the crop rectangle on a subdev pad</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>struct v4l2_subdev_crop *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_subdev_crop *<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Arguments</title> + + <variablelist> + <varlistentry> + <term><parameter>fd</parameter></term> + <listitem> + <para>&fd;</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>request</parameter></term> + <listitem> + <para>VIDIOC_SUBDEV_G_CROP, VIDIOC_SUBDEV_S_CROP</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + <para>This is an <link linkend="experimental">experimental</link> + interface and may change in the future.</para> + </note> + + <para>To retrieve the current crop rectangle applications set the + <structfield>pad</structfield> field of a &v4l2-subdev-crop; to the + desired pad number as reported by the media API and the + <structfield>which</structfield> field to + <constant>V4L2_SUBDEV_FORMAT_ACTIVE</constant>. They then call the + <constant>VIDIOC_SUBDEV_G_CROP</constant> ioctl with a pointer to this + structure. The driver fills the members of the <structfield>rect</structfield> + field or returns &EINVAL; if the input arguments are invalid, or if cropping + is not supported on the given pad.</para> + + <para>To change the current crop rectangle applications set both the + <structfield>pad</structfield> and <structfield>which</structfield> fields + and all members of the <structfield>rect</structfield> field. They then call + the <constant>VIDIOC_SUBDEV_S_CROP</constant> ioctl with a pointer to this + structure. The driver verifies the requested crop rectangle, adjusts it + based on the hardware capabilities and configures the device. Upon return + the &v4l2-subdev-crop; contains the current format as would be returned + by a <constant>VIDIOC_SUBDEV_G_CROP</constant> call.</para> + + <para>Applications can query the device capabilities by setting the + <structfield>which</structfield> to + <constant>V4L2_SUBDEV_FORMAT_TRY</constant>. When set, 'try' crop + rectangles are not applied to the device by the driver, but are mangled + exactly as active crop rectangles and stored in the sub-device file handle. + Two applications querying the same sub-device would thus not interact with + each other.</para> + + <para>Drivers must not return an error solely because the requested crop + rectangle doesn't match the device capabilities. They must instead modify + the rectangle to match what the hardware can provide. The modified format + should be as close as possible to the original request.</para> + + <table pgwide="1" frame="none" id="v4l2-subdev-crop"> + <title>struct <structname>v4l2_subdev_crop</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>pad</structfield></entry> + <entry>Pad number as reported by the media framework.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>which</structfield></entry> + <entry>Crop rectangle to get or set, from + &v4l2-subdev-format-whence;.</entry> + </row> + <row> + <entry>&v4l2-rect;</entry> + <entry><structfield>rect</structfield></entry> + <entry>Crop rectangle boundaries, in pixels.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[8]</entry> + <entry>Reserved for future extensions. Applications and drivers must + set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EBUSY</errorcode></term> + <listitem> + <para>The crop rectangle can't be changed because the pad is currently + busy. This can be caused, for instance, by an active video stream on + the pad. The ioctl must not be retried without performing another + action to fix the problem first. Only returned by + <constant>VIDIOC_SUBDEV_S_CROP</constant></para> + </listitem> + </varlistentry> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-subdev-crop; <structfield>pad</structfield> + references a non-existing pad, the <structfield>which</structfield> + field references a non-existing format, or cropping is not supported + on the given subdev pad.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> |
