Changing playback speed by changing frame rate My camera does simple time-lapse but it makes the videos in a 20fps format. I just want to change it to 30fps and yes I want to make the video play faster as a result. I do not want to only change the frames per second, I actually want all the frames to play faster! So it seems like this would be extremely simple, yet I can't find any help on google. I just want a cheap way of changing the frame rate. Thanks
So you want an output video with the same frames in the same order, but with just the timing changed.  No problem.

ffmpeg can't do it without transcoding, unfortunately.  So you'll need a program that can muck around with the timing info in the container.  mkvmerge can do it, and so can MP4Box.

I knew I'd seen an answer to this when I googled on it before:
https://askubuntu.com/questions/370692/how-to-change-the-framerate-of-a-video-without-reencoding

From there: the guy eventually found the right MP4Box command line (since he was working with MP4.)

MP4Box -add test_track1.h264:fps=30 -new dest.mp4

(where test_track1.h264 is the raw h.264 stream he demuxed from his source.mp4)

If a Matroska container works for you, there's also the option of:

mkvmerge -o out.mkv  --default-duration 0:30fps --fix-bitstream-timing-information 0 in.mp4