[FFmpeg-trac] #8925(ffmpeg:new): Concat demuxer shifts video stream start time
FFmpeg
trac at avcodec.org
Fri Oct 9 11:49:46 EEST 2020
#8925: Concat demuxer shifts video stream start time
-------------------------------------+-------------------------------------
Reporter: cake_donkey | Type: defect
Status: new | Priority: normal
Component: ffmpeg | Version:
Keywords: concat | unspecified
demuxer start_pts start_time | Blocked By:
shift |
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
Summary of the bug:
After a single `mp4` video containing video and audio streams both with
`start_time=0` and `start_pts=0` is processed by concat demuxer with `-c
copy` option, video stream `start_time` and `start_pts` are no longer
zero.
This causes the processed video, when opened with QuickTime player on
Mac, to initially display a blank frame, although the rest of the video
plays normally.
Ffmpeg version used:
{{{
ffmpeg version 4.3.1 Copyright (c) 2000-2020 the FFmpeg developers
built with Apple clang version 11.0.3 (clang-1103.0.32.62)
configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1 --enable-shared
--enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-
cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl
--enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame
--enable-libopus --enable-librav1e --enable-librubberband --enable-
libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora
--enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp
--enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid
--enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r
--enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb
--enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr
--enable-videotoolbox --disable-libjack --disable-indev=jack
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
}}}
Ffprobe version used:
{{{
ffprobe version 4.3.1 Copyright (c) 2007-2020 the FFmpeg developers
built with Apple clang version 11.0.3 (clang-1103.0.32.62)
configuration: --prefix=/usr/local/Cellar/ffmpeg/4.3.1 --enable-shared
--enable-pthreads --enable-version3 --enable-avresample --cc=clang --host-
cflags= --host-ldflags= --enable-ffplay --enable-gnutls --enable-gpl
--enable-libaom --enable-libbluray --enable-libdav1d --enable-libmp3lame
--enable-libopus --enable-librav1e --enable-librubberband --enable-
libsnappy --enable-libsrt --enable-libtesseract --enable-libtheora
--enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp
--enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid
--enable-lzma --enable-libfontconfig --enable-libfreetype --enable-frei0r
--enable-libass --enable-libopencore-amrnb --enable-libopencore-amrwb
--enable-libopenjpeg --enable-librtmp --enable-libspeex --enable-libsoxr
--enable-videotoolbox --disable-libjack --disable-indev=jack
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
}}}
How to reproduce:
Given video `before.mp4` containing video and audio streams both with
`start_time=0` and `start_pts=0`.
Given concat demuxer input file `concat.txt` with contents:
{{{
file before.mp4
}}}
Run command `ffmpeg -f concat -i concat.txt -c copy concat.mp4`
Run command `ffprobe concat.mp4 -show_streams` and observe that video
stream `start_time` and `start_pts` are no longer zero.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/8925>
FFmpeg <https://ffmpeg.org>
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