[mythtv-users] newbie audio problems

[Isaac Richards]

On Sunday 15 June 2003 06:02 pm, Stephen Mathezer wrote:
> I'm relatively new to mythtv, I have things sort of working but am
> having trouble with audio quality.
>
> I'm running 0.9.1 on Debian with a 2.4.20 kernel and alsa 0.9.4. I have
> a Gigabyte 7VAXP which has VIA 8235 sound built in.  My capture card is
> a WinTV GO.
>
> With some screwing around I have managed to get btaudio to work with
> analog output on /dev/dsp2. I am able to watch live tv and record. Sound
> quality is however pretty poor no matter what I try.  There is a fair
> bit of hissing and crackling all the time.
>
> If I run xawtv and do the "sox -r 480000 -c 1 -t ossdsp /dev/dsp2 -t
> ossdsp /dev/dsp" thing then sound quality is vastly better. My question
> is, how do I set the sample rate that high in MythTV for both live
> watching and recording? I tried actually setting the samplerate to
> 480000 in the codecparams table manually but that caused backend
> crashes.  If I run sox all the time, then I am getting sound output all
> the time which also isn't good.
>
> I've searched through the mailing list which did help me get btaudio
> going, but I couldn't find any solutions to the poor quality sound.
>
> Can anyone help me out with this?

lame can't encode with a sampling rate that absurdly high, and I doubt the a/v 
sync code in mythtv deals with it either.  Only way you're going to get it 
working is to add some audio resampling code to the record pipeline to bump 
the sample rate down to normal levels.

Isaac