* To set the video bitrate of the output file to 64kbit/s:
ffmpeg -i input.avi -b 64k output.avi
* To force the frame rate of the input and output file to 24 fps:
ffmpeg -r 24 -i input.avi output.avi
* To force the frame rate of the output file to 24 fps:
ffmpeg -i input.avi -r 24 output.avi
* To force the frame rate of input file to 1 fps and the output file to 24 fps:
ffmpeg -r 1 -i input.avi -r 24 output.avi
The format option may be needed for raw input files.
By default, FFmpeg tries to convert as losslessly as possible: It uses the same audio and video parameters for the outputs as the one specified for the inputs.