Opened 5 years ago

Closed 3 years ago

Last modified 3 years ago

#7912 closed defect (fixed)

timing is all wrong when extracting Closed Captions

Reported by: jookiyaya Owned by:
Priority: normal Component: undetermined
Version: git-master Keywords: cc
Cc: Blocked By:
Blocking: Reproduced by developer: yes
Analyzed by developer: no

Description

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

Change History (8)

comment:1 by Carl Eugen Hoyos, 5 years ago

Keywords: cc added
Reproduced by developer: set
Status: newopen
Version: unspecifiedgit-master

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%

comment:2 by Carl Eugen Hoyos, 4 years ago

Summary: timing is all wrong when extract srt subtitle from videotiming is all wrong when extracting Closed Captions

comment:3 by findmyip, 4 years ago

Summary: timing is all wrong when extracting Closed Captionstiming is off by factor of 90 or 3 when extracting srt subtitle from video

comment:4 by findmyip, 4 years ago

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

comment:5 by Carl Eugen Hoyos, 4 years ago

Summary: timing is off by factor of 90 or 3 when extracting srt subtitle from videotiming is all wrong when extracting Closed Captions

comment:6 by Balling, 3 years ago

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?

Last edited 3 years ago by Balling (previous) (diff)

comment:7 by Balling, 3 years ago

So how is a27853a7300bb3c2752256b2fc02f2439619f6f8 affecting this?

comment:8 by Balling, 3 years ago

Resolution: fixed
Status: openclosed

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

Last edited 3 years ago by Balling (previous) (diff)
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