On date Tuesday 2015-02-10 20:43:31 -0700, Deron wrote: > On 2/10/15 3:20 AM, Stefano Sabatini wrote: > >On date Saturday 2015-02-07 22:15:58 -0700, Deron wrote: > >>I'm trying to capture ATSC with a tuner card and stream it out via > >>HLS. I've got it more or less working, and now I would like to try > >>my hand and streaming out closed captioning in WebVTT utilizing the > >>eia 608 demuxer. > >> > >>First, I captured 10 minutes of video to my HD. Then I used: > >> > >>ffmpeg -f lavfi -i "movie=WPEC.ts[out0+subcc]" -map s WPEC.vtt > >> > >>which generated a good .vtt file and then > >> > >>ffmpeg -i WPEC.vtt -f segment -segment_time 10 -segment_format > >>webvtt -scodec copy WPEC-%05d.vtt > >> > >>to generate segments 00000 to 00038 and it works just fine. > >> > >>However, > >> > >>ffmpeg -f lavfi -i "movie=WPEC.ts[out0+subcc]" -map s -f segment > >>-segment_time 10 -segment_format webvtt WPEC-%05d.vtt > >> > >>fails to generate segments. What it generates is just one segment > >>named WPEC-00000.vtt. > >> > >>What am I doing wrong? > >> > >>Deron > >> > >>Complete uncut output: > >> > >># ffmpeg -f lavfi -i "movie=WPEC.ts[out0+subcc]" -map s -f segment > >>-segment_time 10 -segment_format webvtt WPEC-%05d.vtt > >Use -loglevel debug, segment will generate log messages showing the > >input PTSs. Also, are you sure you have many key-frames in your input > >file? > > >
> I can't imagine how PTS or i-frames can be defined in a .vtt ? But > I'm certainly looking for understanding! In a private email, Anshul > Maheshwari suggested that it was incomplete in his WebVTT > implementation and he hopes to get it resolved some day. I've > started trying to just trace along to figure out what it is doing > but it is a large amount of stuff to absorb at once. I wanted to > learn more about HLS, so I'm not apposed to trying to solve the > problem if it needs to be. For example to check for key-frames: ffprobe INPUT -show_entries packet=pts,flags -of compact you check the packet flags to see if it is a key-frame (in that case it will be marked with a "K"). Alternatively: ffprobe INPUT -skip_frames nokey -show_frames -of compact > Thanks for your input, _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user
