[mythtv] Audio for a second tuner [was: no video with mythtv]

Bruce Markey mythtv-dev@snowman.net
Sat, 07 Dec 2002 04:59:57 -0800

Harondel J. Sibble wrote:
> I have my two cards in the machine and they both work fine with Xawtv.  
> However, in Mythtv I don't seem to get anything when I hit V to bring up the 
> PiP window.  I know something is getting written to the ringbuf2.nuv file as 
> it has a time/date stamp of earlier today when I was playing with it.
> Also wondering on what sound devices to use as both cards go through my 
> SBLive!  My AverMedia TVPhone goes in the rear bracket line-in while my ATI 
> TV Wonder goes internally to the auxilliary connector.  When running setup, I 
> used /dev/dsp for audio for both cards as that seemed most appropriate.  Is 
> there a better way of doing thso

You need separate DSP devices for each tuner card. You can
either use the DSPs of two sound cards (which is what I did)
or use the btaudio kernel module (which I haven't done).

I use an SB card instead of the on board sound. When I added
a second bttv card, I plugged the audio jack into the on board
line in and configured the ALSA driver for it as card-1.

# ALSA portion
alias char-major-116 snd
alias snd-card-0 snd-ens1371 # sound blaster
alias snd-card-1 snd-via82xx # on board audio
# OSS/Free portion
alias char-major-14 soundcore
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
alias sound-slot-1 snd-card-1
alias sound-service-1-0 snd-mixer-oss
alias sound-service-1-1 snd-seq-oss
alias sound-service-1-3 snd-pcm-oss
alias sound-service-1-8 snd-seq-oss
alias sound-service-1-12 snd-pcm-oss

"alsamixer -c 1" to set line as the capture device and to
set the volume for line and capture. So now my /dev/dsp1
is the audio device for /dev/video1 .

This worked for me but perhaps ignorance is bliss as I now
assume that btaudio is supposed to be the right way.

 From the kernel Configure.help:

BT878 audio DMA
   Audio DMA support for bt878 based grabber boards.  As you might have
   already noticed, bt878 is listed with two functions in /proc/pci.
   Function 0 does the video stuff (bt848 compatible), function 1 does
   the same for audio data.  This is a driver for the audio part of
   the chip.  If you say 'Y' here you get a oss-compatible dsp device
   where you can record from.  If you want just watch TV you probably
   don't need this driver as most TV cards handle sound with a short
   cable from the TV card to your sound card's line-in.

   This driver is available as a module called btaudio.o ...

Hope this helps,

--  bjm