video encode frame rate change

Question

I have a video in mp4 with frame rate of .33 (i frame for 3 seconds). I want to increase the frame rate to 5 frames/sec. I have tried the below command but it does not do any thing...

ffmpeg -i <input.mp4> -r 5 <output.mp4>

Any idea why ffmpeg is ignoring -r option.

thank you

Answer 1

If the input file doesn't have a valid frame rate you might have to set it explicitly

ffmpeg -r 1 -i input.mp4 -r 24 output.mp4