Free software to stretch or compress video

[smigh]

I want to merge video with audio tracks but most of the time they're out of sync and with different tempos so if I sync them in the beginning, they're out of sync in the end. I can already change the audio's tempo easily but I'd rather change the video and keep the original audio.

Is there any free app that stretches and compresses video out there?

[guns1inger]

Unless you are looking to do this for a particular effect, you are better off changing the audio. There are tools that let you alter the length of an audio track while maintaining the original pitch (Audacity, Sound Forge etc). However altering the speed of video will always be noticeable.

If you do want to match video to audio then you can use virtualdub or avisynth to change the speed of the video, or more complicated avisynth scripts that also frame blend, or bigger tools such as Vegas which have interactive stretching capabilities.