I have an MP4 file containing H.264 Video, AAC Audio, and EIA-608 Closed Captions:
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf57.83.100 Duration: 00:11:26.02, start: 0.000000, bitrate: 4952 kb/s Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], Closed Captions, 4818 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc (default) Metadata: handler_name : VideoHandler Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 125 kb/s (default) Metadata: handler_name : SoundHandler
However, the subtitles are displaying about 2 seconds too early.
The catch is, as you can see, ffmpeg doesn't recognize
eia_608 as a "stream" that can be manipulated with the
-map commands (as in this question). So inputting the file multiple times to remux the subtitles back in with a delay gives the following error:
Stream map '1:s' matches no streams. To ignore this, add a trailing '?' to the map.
-itsoffset affects the video exactly as much as the subtitles in every case, anyway.