timing is all wrong when extracting Closed Captions

[jookiyaya]

ffmpeg -fix_sub_duration -f lavfi -i "movie=test.mkv[out+subcc]" -map 0:1 test.srt

also tried

ffmpeg -fix_sub_duration -real_time 1 -f lavfi -i "movie=test.mkv[out+subcc]" -map 0:1 test.srt

video sample: ​https://x0.at/SrG.mkv

result of test.srt ​https://x0.at/pUA.srt

version 4.1.3

[Carl Eugen Hoyos]

For future tickets: Please always test current FFmpeg git head, nothing else is supported, and provide the command line you tested together with the complete, uncut console output.

$ ffmpeg -f lavfi -i movie=SrG.mkv[out+subcc] out.srt
ffmpeg version N-93886-gfbdb3aa179 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 8 (SUSE Linux)
  configuration: --enable-gpl --enable-gnutls --enable-libxml2 --enable-libx264 --enable-libx265 --enable-libvpx --enable-libaom --enable-libdav1d --enable-libmfx
  libavutil      56. 28.100 / 56. 28.100
  libavcodec     58. 52.101 / 58. 52.101
  libavformat    58. 27.103 / 58. 27.103
  libavdevice    58.  7.100 / 58.  7.100
  libavfilter     7. 53.101 /  7. 53.101
  libswscale      5.  4.101 /  5.  4.101
  libswresample   3.  4.100 /  3.  4.100
  libpostproc    55.  4.100 / 55.  4.100
Input #0, lavfi, from 'movie=SrG.mkv[out+subcc]':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 29.97 fps, 29.97 tbr, 1k tbn, 1k tbc
    Stream #0:1: Subtitle: eia_608
Output #0, srt, to 'out.srt':
  Metadata:
    encoder         : Lavf58.27.103
    Stream #0:0: Subtitle: subrip (srt)
    Metadata:
      encoder         : Lavc58.52.101 srt
Stream mapping:
  Stream #0:1 -> #0:0 (eia_608 (cc_dec) -> subrip (srt))
Press [q] to stop, [?] for help
size=      15kB time=00:00:03.27 bitrate=  38.2kbits/s speed=0.114x     
video:0kB audio:0kB subtitle:10kB other streams:0kB global headers:0kB muxing overhead: 48.054531%

[findmyip]

​https://x0.at/3hu.mp4

ffmpeg -fix_sub_duration -f lavfi -i "movie=3hu.mp4[out+subcc]" -map 0:1 3hu.srt

3hu.srt : timing is off by factor of 3

[Balling]

First of all sample is here now: ​https://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket7912/

Second, mediainfo does not see CC in mkv.

Third, I do not understand what is the actual problem here. And VLC is no help, it looks good, but sees some kind of second stream there of cc?

4th, where is 3hu.mp4?

[Balling]

So how is a27853a7300bb3c2752256b2fc02f2439619f6f8 affecting this?

[Balling]

Fixed in a27853a7300bb3c2752256b2fc02f2439619f6f8. It was happening because SrG.mkv has "1k tbn (default)".