how can i timewarp a video to a lesser length?

[KneeRow]

i have video and the audio is OK but 1 minute shorter than the video, which is 5:50

How do I change the video so that it keeps every frame but shortens it to 4:52, the original audio length?

i've tried changing the framerate from 29 to 25 but maybe i did that wrong, idk?

[Cornucopia]

Since frames per second or "FPS" is Frames / Seconds, and you want to keep the # of frames while shortening the length, you have to do this:

# Frames / Length = #FPS

X frames / 5:50 = 29.97fps
X frames / 4:52 = ?fps

Solving for ? means X frames = 29.97fps * 5:50 = 30 frames/second * 300 seconds = 10500 frames

Plugging it back into the equation:
10500 F/ 4:52 = 10500 frames / 292 seconds = ~35.95 or 36FPS. Simple math

But that's kind of silly, because nobody in their right mind is going to use such a non-standard video framerate. Ask yourself: does the video show the motion at the right speed already? If so, you should be adjusting the length of the Audio, not the Video.

Scott

[DarrellS]

Scott is correct. The best program that I've found to do this is Goldwave which has an option to timewarp the audio but it is not free. Others have used Audacity which is free but I could never figure out how to do it with Audacity. Maybe someone will chime in to explain just how to do it in Audacity.

Goldwave has a fully functional evaluation version...

http://www.goldwave.com/index.php
http://www.goldwaving.com/downloads/gwave568.exe

Open your video in Virtualdub and go to the last frame. Note the time code at the bottom of page. Either save the audio in Virtualdub (file>save WAV) and open in Goldwave or try opening the video itself in Goldwave. Go to Effects>Timewarp and add the timecode that you noted in Virtualdub (5:50.xxx) and clip OK. Select all>Save as>file of choice (yourfile.mp3). In Virtualdub, select Audio>Audio from other file and select yourfile. Test to make sure it plays right and direct stream copy audio and video and save as new file.

[budwzr]

You have to "re-time", or "undersample" the playback rate, then the length will shorten.