Audio Sync Prob with Divx 5.01 & VirtualDub

[BramleyButcher]

I have been struggling with this for some time so I hope someone can help.

I wanted to capture a video sequence but my HD has restricted capacity so I captured the video in two parts (parta.avi, partb.avi). 'Parta.avi' was captured uncompressed using Hauppauge WinTV Theater card and then compressed using VirtualDub and Divx 5.01 codec. The same was then done with 'Partb.avi'.

I then wanted to join the two parts together to create the final video file (in Divx format). I read both files into VirtualDub, selected 'DirectStream' for both video and audio and copied them out to a third file.

The problem then is that when I play back the third (joined together) file the audio is in perfect sync until the point is reached where 'partb.avi' starts and the audio goes completely out of sync. I should point out that both 'parta.avi' and 'partb.avi' seperately play back in perfect sync. 'parta.avi' is 894MB and 'partb.avi' is 364MB after compression using Divx 5.01 codec, I am using Pentium III 930Mhz PC with 256MB Memory.

I hope someone has come across this problem before and can make some suggestions.

[Mac Sidewinder]

The easiest way to fix this is to extract the audio from both clips with virtual dub. Now join both video clips with the audio setting set to none. Join both audio clips together. No mux the video and audio back together.

Mac

[BramleyButcher]

Thanks for the response Mac. Unfortunately, it didn't work. However, splitting the audio and video as you suggested enabled me to notice that the audio track for 'parta.avi' was shorter by a couple of seconds than the video. I shortened the video so that they both matched in length and then spliced on 'partb.avi' audio and video tracks. This had the strange effect of moving the combined video sound out of sync at an earlier point than before, but synchronisation was then reestablished later at the point where before the sync had been lost (the point at which 'partb.avi' was added)!

Its as though the two parts of the video have contesting audio synchronisation information. Does this sound familiar to anyone? After having worked on this sync problem for over a week, I'm reaching the point where I'm about to give up.

[supertrucker]

BramleyButcher; I am having the somewhat same problem but a little different. I downloaded a movie that is over 800MB and I only have 700MB disks. I used Virtual Dub to split the movie in Half, but when you go to play the parts the video comes before the audieo. I have tried to use a command in VD to sync the audieo but I do not think I am doing the math right do you knoe where I am going wrong. John

[BramleyButcher]

Originally posted by Mac Sidewinder
The easiest way to fix this is to extract the audio from both clips with virtual dub. Now join both video clips with the audio setting set to none. Join both audio clips together. No mux the video and audio back together.

Mac

Thanks Mac, I did as you suggested but it made no difference, however splitting the video and audio enabled me to remove a few video frames and get the video and audio back into sync so thanks for pointing me in the right direction.
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[BramleyButcher]

SuperTrucker - Ensure that you split the video on a keyFrame by using the keyframe navigation icons before creating an outpoint for the first clip. This may help if you haven't done so already.

[Mac Sidewinder]

@ Supertrucker

There is a program called AviSplitCalc that will split that file based either on your desired filesize or based on movie time. I have used it numerous times and haven't had any sync problems. You can get it from the d/l section at www.doom9.org.

Mac