Captured video/audio progressively out of sync (on linux)

[daytooner]

I am trying to capture video (and audio) from a TV source (mainly VHS player, but also analog cable).

But the audio becomes progressively out of sync (slower) with the video. This also happens when just playing the captured video (as opposed to recording it on disk).

The stats:

Linux, F11.
P4 2.6GHz, 2G RAM
Pinnacle PC Pro capture card (Conexant chip)

I have tried FFMPeg, and Mencoder/MPlayer. Both give the same results. After about 10 min, the audio is about 3 to 5 seconds behind the video. And that offset continues to grow as the video progresses. I last tried Mencoder, with the following command:

mencoder -tv device=/dev/video0:input=1:adevice=/dev/dsp1:amode=1:immediatemode=0:audiorate=48000:mjpeg :decimation=1:norm=ntsc -vf harddup -vf expand=::::0:1 -mc 0 -o /mnt/xfs/vhs.avi -noskip -forceidx -ni -oac copy -ovc raw tv://

Any help with this will be greatly appreciated (a lot of good karma).

TIA

ken

[redwudz]

The simple answer is your video and audio files are likely different lengths. What part of your procedure is causing it may be a bit more complicated.

And welcome to our forums.

[daytooner]

The simple answer is your video and audio files are likely different lengths. What part of your procedure is causing it may be a bit more complicated.

Yes that is a simple answer .

But there are no "files" involved. This is capturing the video/audio stream from a tv source (via capture card).

I am wondering how/why the two streams become different "lengths". As I said, the out-of-syncing is progressive - it gets more as the capture continues. I noticed that after about 5 minutes captured, the audio is "stretched out" past the video by about 1 second; after about 10 minutes, it becomes 3+ seconds.

I should try to capture the video and audio separately (two passes), then mux them together.

And welcome to our forums.

Thank you.

ken