[mythtv-users] Audio Distortion Problem NForce2 Realtek ALC650

[Robert.Mctasney at colorado.edu]

I have an audio distortion problem that occurs while watching "Live TV" and
recording.  I am using a bttv based video capture card (in the video4linux list
it is listed as card 40).  Analog audio is connected from the video capture card
to the on-board (motherboard) audio (the internal CD input) on a Biostar
motherboard M7NCG 400 ver 7.2 (Realtek ALC650/655 6-Channel AC97 CODEC) with an
Nvidia NForce2 chipset.

I am using alsa audio drivers (MythTV might be using the oss emulation options).
 I am running Fedora Core 4.

I do get audio during "Live TV" and recording, but it distorted.  I think it may
be due to a low sample rate, because when I listen to the audio while running
xawtv with CD unmuted (listening to the live audio feed from the video capture
card) the sound is excellent (not distorted).  When I mute CD and run aplay
/dev/dsp, I get the distortion (same as when I watch "Live TV" or record using
MythTV).  Also, while aplay is running, on the command-line it states that it
is sampling 8-bits, 8000Hz, mono.  When I try to increase the sampling rate
using the aplay -r option, I get underrun errors and the sound is high pitched
that consistently skips.

According to Realtek, the ALC650 has full-duplex capability.  So I'm not sure
why I am having this problem.

I'm looking for any advice on how to fix this audio capture distortion problem. 
I have played with the settings in the .asoundrc file with regard to sample
rate, buffer time, period time, buffer size, channel and period but with no
improvement.  If someone has a .asoundrc they are using for this audio chipset,
that might help also.

I'm really happy with MythTV (ver 0.19).  Everything works very well except for
this audio problem I am having.

Any advice would be appreciated.

Bob McTasney