Extracting and changing the soundtrack

Supposing you have a video of car-crashes and want to add some rousing music, Tschaikowsky's 1812 Overture for example. VirtualDub allows you to do this very easily.

Replacing the audio

Open the video clip, then go to the Audio menu, select Audio from other file and choose your clip. It could be an AVI or MPEG video file, or a WAV or MP3 audio-only file. Then simply save with Direct stream copy enabled on both the Video and Audio menus.

Unfortunately this will probably not produce the result you want due to the clips being of different lengths. This may need some time-consuming editing. If the video is longer than the audio then you can hack away at it fairly freely to get it down to time. If the audio is longer then you can slow down the video (you might want to do this anyway). Go to Video -> Frame Rate..., then under Source rate adjustment select Change so video and audio durations match.

Extracting a soundtrack

You can save the soundtrack from a video clip as a WAV file for editing in an audio program of your choice. Just load the clip, go to the File menu and pick Save WAV....

To save a track from a CD as a WAV you'll need another program. Media Player Classic will do. Just insert the CD, select the track you want, and use the File menu Save As... option to create the WAV file.

Compressing the audio

When saving a clip always use Audio -> Direct stream copy until you're ready to produce the final result. Uncompressed formats such as WAV have the advantage of the View -> Audio display option for easier editing, but will eventually need compressing or the file will be twice the size it ought to be. Audio imported in MP3 or similar formats shouldn't need re-compressing. Use the File -> File Information option to chect that the audio data rate isn't excessive (ie. greater than 192kbps).

Example video

You can often get a cheap but amusing effect by combining a video with a totally unsuitable soundtrack. Here I've taken some nasty blood-and-guts and set it to a beautiful piece by Mozart:

http://rapidshare.com/files/238693851/Cutting-Moments-Mozart-01.avi
(1:42 minutes, 384 x 288, 8MB)