[FFmpeg-trac] #9028(undetermined:new): mp4 durations include edit list delay

[FFmpeg]

#9028: mp4 durations include edit list delay
-------------------------------------+-------------------------------------
             Reporter:  j0sh         |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 When clipping and transmuxing to mp4 (eg, `-ss <seek> -i <in>` ), the
 duration of the resulting clip includes the edit list delay (start time
 offset from the beginning of the clip). This does not match the actual
 track duration.

 Generated the source (also attached):

 ffmpeg -f lavfi -i testsrc=duration=20:rate=30 -an -c:v libx264 -g 60
 test-timecode.mp4

 Now try to trim it. This should attempt to cut in the middle of the second
 GOP, with one extra second of "delay".

 ffmpeg -ss 3 -i test-timecode.mp4 -t 5 -c copy out.mp4

 Note that the reported time is mostly correct: `time=00:00:04.96`

 ```
 ffmpeg -ss 3 -i test-timecode.mp4 -t 5 -c copy out.mp4
 ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
   built with clang version 7.1.0 (tags/RELEASE_710/final)
   configuration: --disable-static --prefix=/nix/store
 /dwplnqraah2ygx9kwl1yklddvwj5x5rw-ffmpeg-full-4.3.1 --target_os=darwin
 --arch=x86_64 --enable-gpl --enable-version3 --disable-nonfree --enable-
 shared --enable-pic --cc=clang --disable-small --enable-runtime-cpudetect
 --disable-lto --enable-gray --enable-swscale-alpha --enable-hardcoded-
 tables --enable-safe-bitstream-reader --enable-pthreads --disable-
 w32threads --disable-os2threads --enable-network --enable-pixelutils
 --enable-ffmpeg --enable-ffplay --enable-ffprobe --enable-avcodec
 --enable-avdevice --enable-avfilter --enable-avformat --enable-avresample
 --enable-avutil --enable-postproc --enable-swresample --enable-swscale
 --enable-doc --disable-htmlpages --enable-manpages --disable-podpages
 --disable-txtpages --enable-bzlib --enable-libcelt --enable-libdav1d
 --disable-libfdk-aac --disable-libflite --enable-fontconfig --enable-
 libfreetype --disable-frei0r --enable-libfribidi --disable-libgme
 --enable-gnutls --enable-libgsm --enable-ladspa --enable-libmp3lame
 --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b
 --disable-libdc1394 --enable-iconv --disable-libjack --disable-libmfx
 --disable-libmodplug --enable-libmysofa --enable-libopus --enable-librsvg
 --enable-libsrt --enable-libssh --enable-libtheora --disable-libv4l2
 --disable-vaapi --enable-vdpau --enable-libvorbis --enable-libvmaf
 --enable-libvpx --enable-libwebp --enable-xlib --enable-libxcb --enable-
 libxcb-shm --enable-libxcb-xfixes --enable-libxcb-shape --enable-lzma
 --disable-nvenc --disable-openal --enable-libopencore-amrnb --disable-
 opengl --enable-libopenjpeg --disable-openssl --disable-libpulse --enable-
 librtmp --enable-sdl2 --enable-libsoxr --enable-libspeex --disable-
 libvidstab --enable-libvo-amrwbenc --enable-libwavpack --enable-libx264
 --disable-libx265 --disable-libxavs --enable-libxvid --enable-libzmq
 --enable-zlib --disable-debug --enable-optimizations --disable-extra-
 warnings --disable-stripping
   libavutil      56. 51.100 / 56. 51.100
   libavcodec     58. 91.100 / 58. 91.100
   libavformat    58. 45.100 / 58. 45.100
   libavdevice    58. 10.100 / 58. 10.100
   libavfilter     7. 85.100 /  7. 85.100
   libavresample   4.  0.  0 /  4.  0.  0
   libswscale      5.  7.100 /  5.  7.100
   libswresample   3.  7.100 /  3.  7.100
   libpostproc    55.  7.100 / 55.  7.100
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'test-timecode.mp4':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     encoder         : Lavf58.45.100
   Duration: 00:00:20.00, start: 0.000000, bitrate: 48 kb/s
     Stream #0:0(und): Video: h264 (High 4:4:4 Predictive) (avc1 /
 0x31637661), yuv444p, 320x240 [SAR 1:1 DAR 4:3], 44 kb/s, 30 fps, 30 tbr,
 15360 tbn, 60 tbc (default)
     Metadata:
       handler_name    : VideoHandler
 File 'out.mp4' already exists. Overwrite? [y/N] y
 Output #0, mp4, to 'out.mp4':
   Metadata:
     major_brand     : isom
     minor_version   : 512
     compatible_brands: isomiso2avc1mp41
     encoder         : Lavf58.45.100
     Stream #0:0(und): Video: h264 (High 4:4:4 Predictive) (avc1 /
 0x31637661), yuv444p, 320x240 [SAR 1:1 DAR 4:3], q=2-31, 44 kb/s, 30 fps,
 30 tbr, 15360 tbn, 15360 tbc (default)
     Metadata:
       handler_name    : VideoHandler
 Stream mapping:
   Stream #0:0 -> #0:0 (copy)
 Press [q] to stop, [?] for help
 frame=  182 fps=0.0 q=-1.0 Lsize=      40kB time=00:00:04.96 bitrate=
 65.5kbits/s speed=4.94e+03x
 video:37kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 8.035690%
 ```

 Results from ffprobe. The top-level duration is incorrect (because it
 includes the extra 1s of delay at the beginning), but the stream duration
 is correct.

 ```
 $ ffprobe -show_streams -show_format out.mp4 2>&1 | grep duration=
 duration=5.166992 # stream duration - correct
 duration=6.167000 # top level duration - incorrect
 ```

--
Ticket URL: <https://trac.ffmpeg.org/ticket/9028>
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