[FFmpeg-user] subtitle for mp4

[James Lee]

Hi,

Does ffmpeg can only embed mov_text subtitle format for mp4?
Srt or ass doesn't work.
ffmpeg -i vid.mp4 -f ass -i vid.ass -c:v copy -c:a copy -c:s ass 
subtitle.mp4
ffmpeg -i vid.mp4 -f srt -i vid.srt -c:v copy -c:a copy -c:s srt 
subtitle.mp4
Both commands throw an error:
Could not write header for output file #0 (incorrect codec parameters 
?): Invalid argument

However, this work.
ffmpeg -i vid.mp4 -f ass -i vid.ass -c:v copy -c:a copy -c:s mov_text 
subtitle.mp4

I use ffmpeg version N-71455-gfbdaebb.
Thanks,

JL