[FFmpeg-trac] #6703(avformat:new): ffmpeg rounds duration_ts and duration

[FFmpeg]

#6703: ffmpeg rounds duration_ts and duration
-------------------------------------+-------------------------------------
             Reporter:  mucikiki     |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:  avformat
              Version:  git-master   |               Resolution:
             Keywords:  mov edts     |               Blocked By:
  duration regression                |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------

Comment (by mucikiki):

 First concat:
 {{{
 /usr/local/bin/ffmpeg -f concat -i /var/www/html/1/download/test-1-2.txt
 -c copy /var/www/html/1/download/test1concat.mp4
 ffmpeg version N-85647-g59d219b Copyright (c) 2000-2017 the FFmpeg
 developers
   built with gcc 4.9.2 (Debian 4.9.2-10)
   configuration: --prefix=/root/ffmpeg_build --pkg-config-flags=--static
 --extra-cflags=-I/root/ffmpeg_build/include --extra-
 ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --enable-gpl --enable-
 libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame
 --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx
 --enable-libx264 --enable-libx265 --enable-nonfree
   libavutil      55. 61.100 / 55. 61.100
   libavcodec     57. 93.100 / 57. 93.100
   libavformat    57. 72.101 / 57. 72.101
   libavdevice    57.  7.100 / 57.  7.100
   libavfilter     6. 87.100 /  6. 87.100
   libswscale      4.  7.101 /  4.  7.101
   libswresample   2.  8.100 /  2.  8.100
   libpostproc    54.  6.100 / 54.  6.100
 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x3912a20] Auto-inserting h264_mp4toannexb
 bitstream filter
 Input #0, concat, from '/var/www/html/1/download/test-1-2.txt':
   Duration: N/A, start: 0.000000, bitrate: 30 kb/s
     Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv,
 bt709), 1280x720, 30 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc
     Metadata:
       creation_time   : 2017-09-30T12:49:58.000000Z
       handler_name    : Alias Data Handler
       encoder         : AVC Coding
 Output #0, mp4, to '/var/www/html/1/download/test1concat.mp4':
   Metadata:
     encoder         : Lavf57.72.101
     Stream #0:0(eng): Video: h264 (Main) ([33][0][0][0] / 0x0021),
 yuv420p(tv, bt709), 1280x720, q=2-31, 30 kb/s, 29.97 fps, 29.97 tbr, 30k
 tbn, 30k tbc
     Metadata:
       creation_time   : 2017-09-30T12:49:58.000000Z
       handler_name    : Alias Data Handler
       encoder         : AVC Coding
 Stream mapping:
   Stream #0:0 -> #0:0 (copy)
 Press [q] to stop, [?] for help
 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x39182c0] Auto-inserting h264_mp4toannexb
 bitstream filter
 frame=  374 fps=0.0 q=-1.0 Lsize=      51kB time=00:00:12.41 bitrate=
 33.7kbits/s speed=1.17e+03x
 video:47kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 8.141509%
 }}}

 Second concat:
 {{{
 root at Debian2:/home/t2s4e0p# /usr/local/bin/ffmpeg -f concat -i
 /var/www/html/1/download/test-1-2b.txt -c copy
 /var/www/html/1/download/test2concat.mp4
 ffmpeg version N-85647-g59d219b Copyright (c) 2000-2017 the FFmpeg
 developers
   built with gcc 4.9.2 (Debian 4.9.2-10)
   configuration: --prefix=/root/ffmpeg_build --pkg-config-flags=--static
 --extra-cflags=-I/root/ffmpeg_build/include --extra-
 ldflags=-L/root/ffmpeg_build/lib --bindir=/root/bin --enable-gpl --enable-
 libass --enable-libfdk-aac --enable-libfreetype --enable-libmp3lame
 --enable-libopus --enable-libtheora --enable-libvorbis --enable-libvpx
 --enable-libx264 --enable-libx265 --enable-nonfree
   libavutil      55. 61.100 / 55. 61.100
   libavcodec     57. 93.100 / 57. 93.100
   libavformat    57. 72.101 / 57. 72.101
   libavdevice    57.  7.100 / 57.  7.100
   libavfilter     6. 87.100 /  6. 87.100
   libswscale      4.  7.101 /  4.  7.101
   libswresample   2.  8.100 /  2.  8.100
   libpostproc    54.  6.100 / 54.  6.100
 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x2dcea20] Auto-inserting h264_mp4toannexb
 bitstream filter
 Input #0, concat, from '/var/www/html/1/download/test-1-2b.txt':
   Duration: N/A, start: 0.000000, bitrate: 14 kb/s
     Stream #0:0(eng): Video: h264 (Main) (avc1 / 0x31637661), yuv420p,
 1280x720, 14 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc
     Metadata:
       handler_name    : VideoHandler
 Output #0, mp4, to '/var/www/html/1/download/test2concat.mp4':
   Metadata:
     encoder         : Lavf57.72.101
     Stream #0:0(eng): Video: h264 (Main) ([33][0][0][0] / 0x0021),
 yuv420p, 1280x720, q=2-31, 14 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc
     Metadata:
       handler_name    : VideoHandler
 Stream mapping:
   Stream #0:0 -> #0:0 (copy)
 Press [q] to stop, [?] for help
 [mov,mp4,m4a,3gp,3g2,mj2 @ 0x2df9180] Auto-inserting h264_mp4toannexb
 bitstream filter
 frame=  374 fps=0.0 q=-1.0 Lsize=      27kB time=00:00:12.37 bitrate=
 17.7kbits/s speed=1.57e+03x
 video:21kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: 24.252748%
 }}}

 I noticed a great difference in muxing overhead, maybe it can be useful.

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6703#comment:6>
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