How can I convert a MKV to MP4 using FFmpeg and hardsub the subtitles?

Question

I use the following command :

ffmpeg -i old_video.mkv -vcodec copy -acodec copy -c:s mov_text new_video.mp4

It does convert the mkv to mp4, but the resulting mp4 doesn't have the subtitles hardcoded but as a separate channel, which is a problem as my TV doesn't support subtitles (but they show in a media player with subtitles support).

Solution

Use

ffmpeg -i old_video.mkv -vf subtitles=old_video.mkv -acodec copy new_video.mp4