[FFmpeg-trac] #10949(undetermined:new): Cutting videos with ass streams (duration and timestamps)

[FFmpeg]

#10949: Cutting videos with ass streams (duration and timestamps)
--------------------------------------+----------------------------------
             Reporter:  x-yuri        |                     Type:  defect
               Status:  new           |                 Priority:  normal
            Component:  undetermined  |                  Version:  6.1.1
             Keywords:                |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
--------------------------------------+----------------------------------
 {{{
 // the video is 20 seconds long
 $ ffprobe -i a.mkv |& grep -E 'Duration:| DURATION |Stream' | grep -v
 STATISTICS
   Duration: 00:00:20.00, start: 0.000000, bitrate: 2223 kb/s
   Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080 [SAR
 1:1 DAR 16:9], 25 fps, 25 tbr, 1k tbn (default)
       DURATION        : 00:00:20.003000000
   Stream #0:1(spa): Audio: vorbis, 48000 Hz, 5.1, fltp
       DURATION        : 00:00:20.003000000
   Stream #0:2(eng): Subtitle: ass
       DURATION        : 00:00:18.523000000

 $ ffmpeg -i a.mkv a.ass

 // cut -ss 10 -to 20
 $ ffmpeg -i a.mkv -ss 10 b.mkv

 // the overall and ass stream duration is 20 seconds
 $ ffprobe -i b.mkv |& grep -E 'Duration:| DURATION |Stream' | grep -v
 STATISTICS
   Duration: 00:00:18.53, start: 0.000000, bitrate: 1450 kb/s
   Stream #0:0: Video: h264 (High), yuv420p(progressive), 1920x1080 [SAR
 1:1 DAR 16:9], 25 fps, 25 tbr, 1k tbn (default)
       DURATION        : 00:00:10.003000000
   Stream #0:1(spa): Audio: vorbis, 48000 Hz, 5.1, fltp
       DURATION        : 00:00:10.016000000
   Stream #0:2(eng): Subtitle: ass
       DURATION        : 00:00:18.526000000

 $ ffmpeg -i b.mkv b.ass

 // it removed the dialogues, but didn't change the timestamps
 // actually the timestamps changed a bit, but not enough and in the wrong
 direction
 $ diff -u a.ass b.ass
 --- a.ass       2024-04-06 03:08:02.822240448 +0300
 +++ b.ass       2024-04-06 03:08:46.379108389 +0300
 @@ -12,9 +12,7 @@

  [Events]
  Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV,
 Effect, Text
 -Dialogue: 0,0:00:06.04,0:00:08.36,Default,,0,0,0,,{\c&HFFFFFF&}Where's
 the surgical instrument kit?{\c}
 -Dialogue: 0,0:00:08.44,0:00:10.64,Default,,0,0,0,,{\c&HFFFFFF&}-There's a
 scalpel in it.{\c}\N{\c&HFFFFFF&}-Berlin has it.{\c}
 -Dialogue: 0,0:00:11.40,0:00:14.40,Default,,0,0,0,,{\c&HFFFFFF&}The
 surgeons!{\c}\N{\c&HFFFFFF&}Go steal tools from them. Hurry!{\c}
 -Dialogue: 0,0:00:14.48,0:00:15.36,Default,,0,0,0,,{\c&HFFFFFF&}Okay.{\c}
 -Dialogue: 0,0:00:15.44,0:00:16.52,Default,,0,0,0,,{\c&HFFFFFF&}Wait!{\c}
 -Dialogue: 0,0:00:17.12,0:00:18.52,Default,,0,0,0,,{\c&HFFFFFF&}Give him
 this note, please.{\c}
 +Dialogue: 0,0:00:11.41,0:00:14.41,Default,,0,0,0,,{\c&HFFFFFF&}The
 surgeons!{\c}\N{\c&HFFFFFF&}Go steal tools from them. Hurry!{\c}
 +Dialogue: 0,0:00:14.49,0:00:15.37,Default,,0,0,0,,{\c&HFFFFFF&}Okay.{\c}
 +Dialogue: 0,0:00:15.45,0:00:16.53,Default,,0,0,0,,{\c&HFFFFFF&}Wait!{\c}
 +Dialogue: 0,0:00:17.13,0:00:18.53,Default,,0,0,0,,{\c&HFFFFFF&}Give him
 this note, please.{\c}

 $ ffmpeg -version
 ffmpeg version n6.1.1 Copyright (c) 2000-2023 the FFmpeg developers
 built with gcc 13.2.1 (GCC) 20230801
 configuration: --prefix=/usr --disable-debug --disable-static --disable-
 stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto
 --enable-fontconfig --enable-frei0r --enable-gmp --enable-gnutls --enable-
 gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray
 --enable-libbs2b --enable-libdav1d --enable-libdrm --enable-libfreetype
 --enable-libfribidi --enable-libgsm --enable-libharfbuzz --enable-
 libiec61883 --enable-libjack --enable-libjxl --enable-libmodplug --enable-
 libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-
 libopenjpeg --enable-libopenmpt --enable-libopus --enable-libplacebo
 --enable-libpulse --enable-librav1e --enable-librsvg --enable-
 librubberband --enable-libsnappy --enable-libsoxr --enable-libspeex
 --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora
 --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis
 --enable-libvpl --enable-libvpx --enable-libwebp --enable-libx264
 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid
 --enable-libzimg --enable-nvdec --enable-nvenc --enable-opencl --enable-
 opengl --enable-shared --enable-vapoursynth --enable-version3 --enable-
 vulkan
 libavutil      58. 29.100 / 58. 29.100
 libavcodec     60. 31.102 / 60. 31.102
 libavformat    60. 16.100 / 60. 16.100
 libavdevice    60.  3.100 / 60.  3.100
 libavfilter     9. 12.100 /  9. 12.100
 libswscale      7.  5.100 /  7.  5.100
 libswresample   4. 12.100 /  4. 12.100
 libpostproc    57.  3.100 / 57.  3.100
 }}}
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10949>
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