problem audio-video

[billman1234]

Hello,
I am facing a strange problem :
I have found some episodes of a cartoon dubbed in my native language but they have poor video quality. So, I try to take the audio and merge it into the same video files which are in french but they have superb video quality. I take the audio from the dubbed files by converting them to mp3, and then I merge the audio with the good quality video files using avimux. However, in this format audio and video are totally desync, so I use virtual dub mod this way : I press Ctrl+R and I choose "Change so video and audio durations match" . This way, I have made the first 3 episodes perfectly dubbed!! However, on episodes 4 and 5, while following the same process, after the use of virtualdub, sound and video are totally desync (in fact firstly audio comes late, and then it comes too early in the same video file!!!) I can't really imagine why this happens in files 4 and 5, because it worked prefectly for files 1, 2 and 3!!
Any ideas ?

[redwudz]

Make sure the audio and video lengths are the same. Sometimes a video or the audio has been edited and that can cause a sync problem when trying to match them. If they are exactly the same length, then you need a offset to correct the start of the audio. You can play the video with the new audio in Media Player Classic and adjust the offset till it's right, then note down the offset amount and use AVIDemux or VirtualDub to add that offset to the audio, then save it.

If the audio sync error gets worse as the video plays, then the lengths are likely different. You may be able to stretch or compress the audio to fit with Audacity. If some audio has been edited out, then it's harder as you usually have to adjust each part of the audio by adding silence to pad it out so the sync matches the duration of the video.

[billman1234]

thank you! I will try to stretch the audio with audacity. Is there any guide in videohelp.com on how exactly I can do that ?

[billman1234]

I just noticed something else about the first 3 episodes in which sound and video matched perfectly : while on the first episode the initial audio and the good quality video actually have the same length, in episode 2 their lengths are different!!! However, the audio matched perfectly with the video!! I just cannot explain it!!!