This is easy with
ffmpeg -framerate 24 -i input.264 -c copy output.mp4
- This simply stream copies (re-muxes) the video so there is no unnecessary re-encoding occurring; therefore the quality is preserved and the whole process is quick.
- Frame rate is by default assumed to be 25. You can change this with the
-framerateinput option. Typical values are
24, or frame rate aliases such as
- If you don’t know the frame rate, you can perform the conversion using your best guess as to the frame rate, and then compare the running duration of the output file with the input file running duration and then calculate the actual frame rate. e.g. assume 24 fps and actual running time of 1:00:00 (60 mins) if resulting file has running time of 1:02:30 (62.5 mins) then actual frame rate is 25 fps (24 * 62.5 / 60)