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author | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-12 21:58:13 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-12-12 21:58:13 -0800 |
commit | e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba (patch) | |
tree | f63906f41699c8e38af9d12b063e2ceab0286ef2 /Documentation/sound/cards/bt87x.rst | |
parent | e34bac726d27056081d0250c0e173e4b155aa340 (diff) | |
parent | 868c97a846a73e937d835b09b8c885a69df50ec8 (diff) | |
download | op-kernel-dev-e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba.zip op-kernel-dev-e7aa8c2eb11ba69b1b69099c3c7bd6be3087b0ba.tar.gz |
Merge tag 'docs-4.10' of git://git.lwn.net/linux
Pull documentation update from Jonathan Corbet:
"These are the documentation changes for 4.10.
It's another busy cycle for the docs tree, as the sphinx conversion
continues. Highlights include:
- Further work on PDF output, which remains a bit of a pain but
should be more solid now.
- Five more DocBook template files converted to Sphinx. Only 27 to
go... Lots of plain-text files have also been converted and
integrated.
- Images in binary formats have been replaced with more
source-friendly versions.
- Various bits of organizational work, including the renaming of
various files discussed at the kernel summit.
- New documentation for the device_link mechanism.
... and, of course, lots of typo fixes and small updates"
* tag 'docs-4.10' of git://git.lwn.net/linux: (193 commits)
dma-buf: Extract dma-buf.rst
Update Documentation/00-INDEX
docs: 00-INDEX: document directories/files with no docs
docs: 00-INDEX: remove non-existing entries
docs: 00-INDEX: add missing entries for documentation files/dirs
docs: 00-INDEX: consolidate process/ and admin-guide/ description
scripts: add a script to check if Documentation/00-INDEX is sane
Docs: change sh -> awk in REPORTING-BUGS
Documentation/core-api/device_link: Add initial documentation
core-api: remove an unexpected unident
ppc/idle: Add documentation for powersave=off
Doc: Correct typo, "Introdution" => "Introduction"
Documentation/atomic_ops.txt: convert to ReST markup
Documentation/local_ops.txt: convert to ReST markup
Documentation/assoc_array.txt: convert to ReST markup
docs-rst: parse-headers.pl: cleanup the documentation
docs-rst: fix media cleandocs target
docs-rst: media/Makefile: reorganize the rules
docs-rst: media: build SVG from graphviz files
docs-rst: replace bayer.png by a SVG image
...
Diffstat (limited to 'Documentation/sound/cards/bt87x.rst')
-rw-r--r-- | Documentation/sound/cards/bt87x.rst | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/Documentation/sound/cards/bt87x.rst b/Documentation/sound/cards/bt87x.rst new file mode 100644 index 0000000..912732d --- /dev/null +++ b/Documentation/sound/cards/bt87x.rst @@ -0,0 +1,83 @@ +================= +ALSA BT87x Driver +================= + +Intro +===== + +You might have noticed that the bt878 grabber cards have actually +*two* PCI functions: +:: + + $ lspci + [ ... ] + 00:0a.0 Multimedia video controller: Brooktree Corporation Bt878 (rev 02) + 00:0a.1 Multimedia controller: Brooktree Corporation Bt878 (rev 02) + [ ... ] + +The first does video, it is backward compatible to the bt848. The second +does audio. snd-bt87x is a driver for the second function. It's a sound +driver which can be used for recording sound (and *only* recording, no +playback). As most TV cards come with a short cable which can be plugged +into your sound card's line-in you probably don't need this driver if all +you want to do is just watching TV... + +Some cards do not bother to connect anything to the audio input pins of +the chip, and some other cards use the audio function to transport MPEG +video data, so it's quite possible that audio recording may not work +with your card. + + +Driver Status +============= + +The driver is now stable. However, it doesn't know about many TV cards, +and it refuses to load for cards it doesn't know. + +If the driver complains ("Unknown TV card found, the audio driver will +not load"), you can specify the ``load_all=1`` option to force the driver to +try to use the audio capture function of your card. If the frequency of +recorded data is not right, try to specify the ``digital_rate`` option with +other values than the default 32000 (often it's 44100 or 64000). + +If you have an unknown card, please mail the ID and board name to +<alsa-devel@alsa-project.org>, regardless of whether audio capture works +or not, so that future versions of this driver know about your card. + + +Audio modes +=========== + +The chip knows two different modes (digital/analog). snd-bt87x +registers two PCM devices, one for each mode. They cannot be used at +the same time. + + +Digital audio mode +================== + +The first device (hw:X,0) gives you 16 bit stereo sound. The sample +rate depends on the external source which feeds the Bt87x with digital +sound via I2S interface. + + +Analog audio mode (A/D) +======================= + +The second device (hw:X,1) gives you 8 or 16 bit mono sound. Supported +sample rates are between 119466 and 448000 Hz (yes, these numbers are +that high). If you've set the CONFIG_SND_BT87X_OVERCLOCK option, the +maximum sample rate is 1792000 Hz, but audio data becomes unusable +beyond 896000 Hz on my card. + +The chip has three analog inputs. Consequently you'll get a mixer +device to control these. + + +Have fun, + + Clemens + + +Written by Clemens Ladisch <clemens@ladisch.de> +big parts copied from btaudio.txt by Gerd Knorr <kraxel@bytesex.org> |