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authorTakashi Iwai <tiwai@suse.de>2016-11-10 18:59:08 +0300
committerTakashi Iwai <tiwai@suse.de>2016-11-11 00:33:26 +0300
commit7bb97dfdcaca0963d59f986e0a88d5bcd0783552 (patch)
treed8e7f467e3537a45096021309f39a905e81b801e /Documentation/sound/cards
parent3d8e81862ce404d861b75bcb1e7d986e4febb025 (diff)
downloadlinux-7bb97dfdcaca0963d59f986e0a88d5bcd0783552.tar.xz
ALSA: doc: ReSTize Bt87x.txt
Another simple conversion from a plain text file. Put to cards directory. Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'Documentation/sound/cards')
-rw-r--r--Documentation/sound/cards/bt87x.rst83
-rw-r--r--Documentation/sound/cards/index.rst1
2 files changed, 84 insertions, 0 deletions
diff --git a/Documentation/sound/cards/bt87x.rst b/Documentation/sound/cards/bt87x.rst
new file mode 100644
index 000000000000..912732d3ef9e
--- /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>
diff --git a/Documentation/sound/cards/index.rst b/Documentation/sound/cards/index.rst
index 0006bc547bb8..157372faae06 100644
--- a/Documentation/sound/cards/index.rst
+++ b/Documentation/sound/cards/index.rst
@@ -12,3 +12,4 @@ Card-Specific Information
via82xx-mixer
audiophile-usb
mixart
+ bt87x