[mythtv-users] What would cause choppy audio recording?

[Michael T. Dean]

Brian McEntire wrote:

> I'm recording OTA HDTV with a PC HD-3000 card.
>
> The video quality looks perfect, rarely pixelates, but the audio is 
> very bad: it sounds choppy, echos frequently, and has a pulsing 
> quality to it.
>
> I'm recording on a P3 1.6 with 768 MB RAM. From what I understand, 
> recording OTA HDTV doesn't take a lot of resources because the card is 
> just capturing the (already encoded) MPEG2 stream from within the ATSC 
> broadcast.
>
> I think the problem does lay in the capture side though because even 
> if I transcode a captured show to xvid using nuvexport, the audio 
> still sounds the same on playback and I think those transcoded formats 
> wouldn't tax the CPU enough to cause audio problems.

Actually, MPEG-4 (DivX, XviD, etc.) requires more resources to decode 
than MPEG-2.  Basically, the higher the compression, the harder your CPU 
has to work (for both compression and decompression).  H.264 gives even 
more compression than MPEG-4, but will put the the best-on-the-market 
general-purpose CPU's to the test for decoding a 1920x1080 stream.

So, how about fessing up--what kind of system are you using to play back 
the video?  Have you tried playing it back in other players (i.e. 
MPlayer or xine)?  Have you tested it on a Windows machine?  It sounds 
to me like a playback problem since--as you correctly observed--HDTV 
capture is just writing the already-encoded MPEG-2 stream to disk.

Mike