Gradual offset

[asian215]

What do you guys do when you have a video clip that changes gradually in respect to the audio and video sync. At the beginning it's only a little off, but by the end it's way off. Does anyone know how to cure this? Also what causes this? I downloaded the file from a filesharing program if it matters. It's in AVI format too.

[Olli]

If it is a framerate conversion problem (e.g you are converting an NTSC source to PAL in TMPGEnc) you can do the following:

Please note this is my own guide for doing framerate conversion to XVCD, but the same steps apply


1) Extract the audio to wav using Virtual Dub
Go to the audio menu and set audio to full processing mode.
Then select File -> Save WAV to save the audio track as an uncompressed WAV file to your harddisk

2) Then find out the 25 fps video length of the decompressed avi using avifrate - change fps to 25 then write down the new length of the film exactly (to 3dp) in seconds .

3) Use "avi frame rate changer" to change the frame rate header of the decompressed avi to 25fps and execute the change.

4) Use "cool edit" to stretch the audio to the exact length of the video file as found in (2)
When the program opens you will be presented with a box allowing you to choose 2 options. Choose options 1 and 3.

In the program click file>open and open the wav you created earlier.
Wait for it to finish then click 'Edit' and untick 'enable undo' then click 'select entire wave' next click 'Transform' and choose 'Time/pitch' from the drop down menu then click 'stretch'
In this box tick the following options:

Low precision (can use High precision if you have a fast CPU)
Time stretch (preserves pitch)
In the length box enter the exact length of the decompressed avi in seconds as found in (2)
Pitch and time settings - check choose appropriate default

When its finished (it spends a long time on 99% before completing) click 'file' then 'save as' and name and save your file as a wav.
This should give you a Wav file which will be the same length as the decompressed AVI.

5) Then encode to XVCD template in TMPGenc specifying the decompressed avi that was changed to 25fps using avifrate as video source and the stretched wav as audio source - Note this will still use toolame and ssrc if they are specified as external tools in TMPGenc