Multimedia support forum - Wierd A-V sync problem

Author

Wierd A-V sync problem

RedFox

2004-09-22, 7:27 pm

I have a VHS tape that plays perfectly to DScaler and when capturing with
AVI_IO
in preview mode.

When playing to AVI_IO prior to capture, the video is a bit jerky and the
sound out of sync.
The capture is the same - jerky and the sound out of sync.-, although in
preview while capturing,
it is fine.

OS - Win2K SP4 with Athlon XP 2100+, AVI_IO is the latest, capture hardware
is Hauppauge WinTV-FM card and the sound is fed from the VCR to the sound
board directly. .

Help appreciated.

RF

Markus Zingg

2004-09-22, 7:27 pm

>I have a VHS tape that plays perfectly to DScaler and when capturing with
>AVI_IO
>in preview mode.
>
>When playing to AVI_IO prior to capture, the video is a bit jerky and the
>sound out of sync.
>The capture is the same - jerky and the sound out of sync.-, although in
>preview while capturing,
>it is fine.

I honestly don't understand propperly what you mean. Do you
experinence problems while capturing or if you use avi_io's player?

You can check if the FILE is in sync by compareing the audio sample
number with the number of frames in relation to the respecitve sample
rates. I.e. if you use NTSC, divide the number of frames by 29.97. Do
the same with audio (the number of audio sampels divided by the audio
sample rate). The resulting numbers should be identical up to some
digits behind the radix.

>OS - Win2K SP4 with Athlon XP 2100+, AVI_IO is the latest, capture hardware
>is Hauppauge WinTV-FM card and the sound is fed from the VCR to the sound
>board directly. .

huffyuv is known to cause problem with playback cause the decoder is
not so optimised.

I'm sure you may get help here if you clarify the situation a bit.

Markus

RedFox

2004-09-22, 7:27 pm

Hello Marcus

Great to have your help. Thanks :-)

"Markus Zingg" <m.zingg@nct.ch> wrote in message
news:gh74i09q0kpjqni4lbeugp741tkb5jin0a@4ax.com...
>
> I honestly don't understand propperly what you mean. Do you
> experinence problems while capturing or if you use avi_io's player?

I was not using AVI_IO as a player. No problems making captures. While
watching
the video in AVI_IO (set to preview) just before pressing the Capture
button, the
sound and video are a bit jerky. While capturing, the video and audio are
normal - in sync and no jerkiness. Playback with any program shows the audio
out of sync.

> You can check if the FILE is in sync by compareing the audio sample
> number with the number of frames in relation to the respecitve sample
> rates. I.e. if you use NTSC, divide the number of frames by 29.97. Do
> the same with audio (the number of audio sampels divided by the audio
> sample rate). The resulting numbers should be identical up to some
> digits behind the radix.

I haven't tried that but will do sometime soon.

hardware[color=darkred]
>
> huffyuv is known to cause problem with playback cause the decoder is
> not so optimised.

I made some good captures with HuffyUV and the video looked jerky before
starting to capture
but after capture, in the playback the audio was in sync so there were no
problems. Recently
I used DScaler a bit to watch TV and it has so many settings that I may have
made a bad one.
Do you know if there is any simple way to set the BTWinCap drivers without
using DScaler?
I tried Amcap and was never able to get it to run more than once or twice
without crashing.

> I'm sure you may get help here if you clarify the situation a bit.

My apologies for the lack of clarity and I hope this effort is an
improvement.

Thanks for your help.

RF

> Markus

Markus Zingg

2004-09-22, 7:27 pm

>Do you know if there is any simple way to set the BTWinCap drivers without
>using DScaler?

No, belive it or not but I havent used DScaler up to now. Does just
mean that I'm still short on time.

>I tried Amcap and was never able to get it to run more than once or twice
>without crashing.
>
>
>My apologies for the lack of clarity and I hope this effort is an
>improvement.

Err - not really :-) So, you have a problem with out of synch when
playing the video? I first would verify the files are in synch with
the method described in my previous post. If they are, there is a
problem with one of the renderes involved. The audio board comes to
mind. You could try if they play fine with AVI_IO cause AVI_IO does
not just play both streams but also does synchronise them during
playback. So after these basic checks I would try to either get new /
updated audio board drivers or consider replacing the board. While we
are at it, choose the SIMPLEST board you can get. All those fancy
features like 3D sound etc pp just add delay and complexity and are
counter productive in the context of video editing.

Markus