replace audio in a avi file.

[bigjohnny002]

how do i replace audio in a movie, avi format, with a better audio from another source? i have 2 of the same movie but one has good video quality but bad audio and the other, just the opposite. i want to put both good audio and video together. i do have virtualdub.

[redwudz]

In VD, disable the old audio and add in the new one, then save out all in Direct stream mode. But the audio length has to match exactly or you will have sync problems. (It rarely does ) I find VD Mod a bit easier for dealing with audio. AVIDemux can do this also.

[bigjohnny002]

it's funny you should mention about the syncing. i tried loading good video, then in the audio tab i chose the avi with the better audio and when i give a go, it's really out of sync. is there any way to adjust the audio with vd.

by the way thanks for the quick response

[guns1inger]

Start by checking if the two videos are the same. Mediainfo's Tree view can help you.

You need to ensure that they have the same framerate (fps) and the same length.

[redwudz]

Two main types of sync problems. First is offset error. That's where the audio begins too early or too late. You can correct this by changing the amount of offset in a program like VirtualDub. It's usually in milliseconds (1/1000 of a second.) You can spot this type of sync problem because the amount of sync error stays the same throughout the length of playback.

Second is audio length error. You can correct this by changing the audio or video length so they match. I use Audacity for this. You can spot this type of error because the sync error gradually gets worse as the video plays.

But it may not be that simple. If your new audio file has other audio added, no simple way to correct the length. Or you may have a combination of both types of sync errors. And it's rare that you would find a alternate audio file that exactly matches the length of your video, unless it was originally a part of that original video. If the lengths are exactly the same and correcting the offset doesn't help, I would give it up.

[bigjohnny002]

i will give a try, just to see what its like. i have been using audacity for a while and virtualdub off and on for a couple of years. i will let you know my progress and again thanks
u 2 guns1inger

[bigjohnny002]

WOW! i check both files with mediainfo as recommended by gunslinger, both files are of same video format, both audio are of mp3 format. BUT file 1 is 8 seconds shorter then file 2 I'm attempting to import good audio from file 1 and add 8sec of blank audio to match up with file 2. wish me luck

[redwudz]

That may or may not work, depending on why it's eight seconds different. But give it a try. Usually if the audio length is different, I use Audacity and shrink or stretch the audio length to match the video. But the two tracks may have slightly different content. Are you sure one's not PAL and the other NTSC? But that would probably be more than eight seconds off, depending on the length of the video.

[bigjohnny002]

im having a problem loading audio track in audicity. how do i load audio from avi file into audicity?

[redwudz]

What I do most times is use VD to demux the audio out, then add that to Audacity. You can add it back the same way, disabling the old audio. Use the Audacity file browser to open the audio. Use the 'Change Tempo' effect if you want to change the length. I usually just leave VD open while I work on the audio file with Audacity.

If the audio is VBR, you can also just save it out as a WAV with full processing and convert it back to MP3 in Audacity, then export.