Usual AV synch problems can be easily solved with Goldwave?

[Phoebos]

As many of us I m having AV synch problems in the mpeg file, meaning that the mpeg file is starting synchronised and then as the time passes the sound is before the video (video follows by 2,3 secs).

I ve been told that the AV synch problems can be eliminated by using Goldwave. I have inserted the wav file in GW but I scratch my head looking at the program's Time Wrap option contents, to understand how the job shall be done. The problem is that I have a progressive asychronisation and not for example 1 sec constant difference all the time which would make things simple. Can you please tell me how GW can solve the problem?

Is there any method (program) to automatically identify asychronisations and correct them, w/o having to check speech and mouth lips?

If you could give me some advice about the easier method to have synched DVDs from captured VHS (avi) I would appreciate.

Thank you in advance

[jimmalenko]

You can demux the MPEG, then check the video and audio file durations - if the sound is out by 3 seconds by the end of the video, this should be reflected in the duration of the audio being 3 seconds shorter/longer than the video.

With the TimeWarp in GW, for videos that start in synch and then drift out, you'd be best off specifying the exact running time of the video as the time you want the audio to be adjusted to. This should fix the problem.

[Phoebos]

Thanks a lot Jimmalenko

if I understood well I will demux the ENCODED mpeg (and NOT encode the avi in separate streams=mp2+mpv)
And to demux the mpeg I could use Vdub to extract the wav file? Then if the wav's length is not 120mins as the original avi but 119 mins+58 secs I will enlong it by 2 secs to make it 120 mins. Am I right?


Thanks

[jimmalenko]

if I understood well I will demux the ENCODED mpeg (and NOT encode the avi in separate streams=mp2+mpv)
And to demux the mpeg I could use Vdub to extract the wav file? Then if the wav's length is not 120mins as the original avi but 119 mins+58 secs I will enlong it by 2 secs to make it 120 mins. Am I right?

Ideally, you should use the AVI source, and get the synch right before encoding to MPEG. You're spot on - use virtualdub or one of it's variants to save the audio out to a WAV file. Then load this WAV into GW and adjust as necessary, saving back out to a new WAV file again. Now when you encode to MPEG, specify this new WAV file as your audio source, or encode both the video and audio portions separately (if you don't want to use PCM), and remux them together in the authoring stage.

If you only have an MPEG source, You can do exactly the same as above - you may need Virtualdub-MPEG2 or VirtualdubMod if you've got an MPEG-2 file. You'd need to then convert this WAV file to MP2 or AC3 if you don't want to use PCM. To add the audio back in, you would demux (I use TMPGEnc's MPEG Tools, but there's even a DOS-based demux.exe somewhere in the tools section), and then remux the video and the new audio.

[lordsmurf]

Audio sync is often a sign of dropped frames.

[Phoebos]

I know lordsmurf but there are not any dropped frames !
Anyway thank you all for your feedback and you have a lot of wishes
for Mery Christmas from Athens if we will not communicate until next week! (I will be out of work for 15 days so I will be experimenting a lot!)

[reboot]

I use this method, for both avi and mpg:
http://club.cdfreaks.com/showthread.php?s=&threadid=59487

[NamPla]

Man, A/V sync issues is like a bloody dog chasing it's tail. You nail it, perfect A/V synced captures etc... Then suddenly it's outa sync again. So you tweak another setting. Fine again! Then...out of sync again. Tweak another setting.

Crikey, I've never worked out why it goes out of sync sometimes.

I wish a tech-head would respond to this, with concrete answers.

HOW COME it is in perfect sync, then (for no apparent reason) is out of sync?

Put it this way, I use VirtualVCR. I started off using this with NOTHING checked under the "AV Sync" tab. Perfect sync. Then it a-sync'd, so I switched on the "resample audio dynamically" switch. Perfect sync again. Then it a-sync'd again, so I switched on "Adjust Stream Offset" and "Offset Audio by 0ms". Perfect sync again.

If it f#cks up again, I guess I'm screwed!