Hi, > I'm trying to process an m4v video with the following subtitle stream: > > Stream #0:3(eng): Subtitle: eia_608 (c608 / 0x38303663), 1920x1080, 0 kb/s > (default) > Metadata: > creation_time : 2014-03-29T03:43:15.000000Z > handler_name : Apple Closed Caption Media Handler > > When I play the video in QuickTime Player, the subtitles are available for > selection and display properly.
Keep in mind closed captions and subtitles have subtle differences, though it seems more like a subtitle in formats like these, where the captions are carried as a separate stream, they are still captions, not text or bitmap subtitles. > If I copy the stream, I get an error: > [ipod @ 0x7f8074810600] Could not find tag for codec eia_608 in stream #0, > codec not currently supported in container > Could not write header for output file #0 (incorrect codec parameters ?): > Invalid argument > (I also tried with extension mp4, behavior is the same.) Try with extension mov, and/or -strict -2. > If I transcode the stream, I get a number of errors, and the resulting > subtitles are garbage: > Stream #0:3 -> #0:0 (eia_608 (cc_dec) -> mov_text (native)) > [Closed caption Decoder @ 0x7fb894079800] Data Ignored since exceeding screen > width > Last message repeated 1529 times > size= 2kB time=00:07:20.53 bitrate= 0.0kbits/s speed=1.2e+04x > video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing > overhead: 2963.333252% > > ~~~~~ > > (To test the output, I used a slightly different invocation, copying the > video/audio streams, and played the file in QuickTime Player. Subtitles are > gibberish.) > > How can I get ffmpeg to play nicely with these subtitles? I think this might be a bug? I didn’t think the captions decoder could decode in a way that direct conversion like cea-708 -> text subtitles was possible, I think it should be saying that and not do this. The gibberish is like if you used cat on a compiled executable I bet. > Suggestions: > - Is there an option to override the "codec not currently supported" error? > Can't ffmpeg just copy the bits and ignore the content? > - Is there another path/tool for transcoding the eia_608 subtitle stream > correctly? > - All I really want at the moment is to strip a "cover art" image appearing > as stream 0:4. Is there another way to accomplish that? - codec not currently supported _in container_ so you can dump the data or use a format that works. Usually broadcast captioning is done with scenarist .scc - Builds with libzvbi support can extract teletext pages to side data, then you can assemble the subtitle track from that I think. Transcoding is tricky because eia_608 is not just text, or even multiple pages of text, it is comparable to the machine language used in dvd subtitles. - Try mapping all input, negative mapping the stream you don’t want, and stream copying into QuickTime (.mov). -strict -2 might be needed. Regards, Ted Park _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
