ffmpeg shortening calculated video run time

Question

I have an image sequence of 5,664 .tga images which are to be played at 24fps (so 236 seconds) and an audio ac3 file which I edited to be exactly 236 seconds (plus minus 0.01s) in length.

I used the following ffmpeg command to mix them into a .mpg file:

ffmpeg -i music.ac3 -i o%04d.tga -r 24 -sameq a.mpg

The audio played for the full 236 seconds; however the video finished at only 226 seconds, holding the final frame for the last 10s of audio.

Why is ffmpeg shortening my image sequence playback by 10s, and how can I get it to run for the full time?

Answer 1

The console output (you should always include this) probably shows that the input is being read at 25 fps. This is the default behavior unless you tell it otherwise. Your -r 24 is being applied to the output and I'm guessing this may be causing your problem. Move -r 24 as an input option so it's before -i o%04d.tga. The output will then inherit this frame rate. Another option to consider is -shortest and will finish encoding within the shortest input (either the audio or video).

Also, -sameq is not a recommended option. It does not mean "same quality". Use -qscale instead. The full range is 1-31, but try values between 2-5. Generally you use the highest value that still looks good to you. See this FFmpeg tutorial for more information and examples.