[mythtv-users] snd-bt87x dsp : was snd-bt87x not detected?

Eric Hattemer eric at hattenator.dyndns.org
Wed Aug 23 07:56:18 UTC 2006

Eric Hattemer wrote:
> With neither the btaudio nor snd-bt87x modules loaded, I can hear faint
> sound if I crank the volume up.  I believe I need something to turn the
> CD-size output on the card on.  I believe what I need is for snd-bt87x
> to create an alsa card that I can control the volume on. 
> Fedora 5 dropped all OSS.  There is no btaudio.  With bt878 and
> snd_bt87x and the CD input cranked all the way up, I could hear some
> tiny sound.  I compiled my own kernel.  I modprobed btaudio without
> snd-bt87x.  I connected mythtv-setup to /dev/dsp1 (never remember doing
> that before).  I managed to get good volume audio, but the video files
> are not synchronized with audio and video anymore, and the audio
> repeats/chops. 

> I am currently compiling the btaudio module into fedora 5's
> 2.6.17-1.2174_FC5 kernel to see if it is less choppy.  If you have an
> ATi TV wonder and are running fedora5, please let me know how your
> modprobe.conf and your lsmod looks, and which device you have
> mythtv-setup using. 

So I've been working on this lately and haven't gotten much farther.  I
put a whole ton of lines into my modprobe.conf without really affecting
anything.  One thing I learned is that with snd_bt87x, the alsa
recording of the tv sound works fine:

arecord -D hw:1,1 -f S16_LE -t wav test.wav

However, the sox recording of the dsp doesn't make any noise but a
slight hiss:

sox -w -r 32000 -t ossdsp /dev/dsp1 -t ossdsp /dev/dsp

So I think its a modprobe.conf issue or a snd_pcm_oss kind of issue. 
Basically if ALSA:1,1 works, but /dev/dsp1 doesn't, its probably an
ALSA-oss translation issue, right?

I changed modprobe.conf around and cut part into modprobe.d/tv.  For
some reason snd_bt87x module doesn't load on boot anymore.  I don't
understand modprobe or udev or how modules are loaded very well.  This
is my new modprobe.d/tv file:

alias char-major-81 bttv
options char-major-81 card=63 gbuffers=4 automute=0 tuner=2
alias tuner0 tuner

# ALSA portion
alias char-major-116 snd
alias snd-card-1 snd-bt87x
options snd-card-1 index=1 load_all=1
# module options should go here

# OSS/Free portion
alias char-major-14 soundcore

# card #1

# OSS/Free portion - card #1
alias sound-slot-0 snd-card-0
alias sound-service-0-0 snd-mixer-oss
alias sound-service-0-1 snd-seq-oss
alias sound-service-0-3 snd-pcm-oss
alias sound-service-0-8 snd-seq-oss
alias sound-service-0-12 snd-pcm-oss

# OSS/Free portion - card #2 (cmipci)
alias sound-slot-1  snd-card-1
alias sound-service-1-0 snd-mixer-oss
alias sound-service-1-3 snd-pcm-oss
alias sound-service-1-12 snd-pcm-oss

#alias sound-slot-1 snd-bt87x
#alias sound-service-1-0 snd-bt87x

#alias sound-slot-2      btaudio
#alias sound-service-2-0 btaudio

-Eric Hattemer

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