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• fate/cbs : Add an SEI test

  8 mai 2018, par Mark Thompson

  fate/cbs : Add an SEI test
  The artificial sample file sei-1.h264 contains five frames (IDR P B I B)
  
  and the following SEI message types :
  
  * Buffering period
  
  * Picture timing
  
  * Pan-scan rectangle (display as 4:3)
  
  * User data registered, containing A/53 closed captions (captions match
  
    frame content, including reordering)
  
  * Recovery point (at the I frame)
  
  * Display orientation (identity transformation)
  
  * Mastering display (with arbitrary contents)
  
  * Undefined SEI type 1234 (containing ascending bytes)
  

  • [DH] tests/fate/cbs.mak
  • [DH] tests/ref/fate/cbs-h264-sei-1

• Why is the resulting clip of my ffmpeg concatenation much longer than expected ?

  21 mai 2018, par joeycato

  I’d like to extract a set of clips from a 60fps input video, change each of their durations, then recombine those modified clips. Unfortunately when I attempt this, the resulting clip doesn’t exactly match the sum of those durations.

  Here’s my repro case :

  1. Extend an extracted 2-second clip to 4 seconds ( input frame count = 120 = 60fps * 2 sec ) )

  ffmpeg -y -ss 8 -t 2 -i ./clip_60fps.avi -filter:v "settb=(4/120),setpts=(4/120)*N/TB" -r 120/4 -vcodec huffyuv step1.avi

  2. Shorten an extracted 4-second clip to 1 second ( input frame count = 240 = 60fps * 4 sec )

  ffmpeg -y -ss 10 -t 4 -i ./clip_60fps.avi -filter:v "settb=(1/240),setpts=(1/240)*N/TB" -r 240/1 -vcodec huffyuv step2.avi

  3. Concatenate the modified clips :

  mylist.txt contents :

  file './step1.avi'
  
  file './step2.avi'

  ffmpeg -y -safe 0 -f concat -i ./mylist.txt -r 60 -vcodec huffyuv steps_joined.avi

  The result :

  ffmpeg -i step1.avi 2>&1 | grep Duration
  
  ffmpeg -i step2.avi 2>&1 | grep Duration
  
  ffmpeg -i steps_joined.avi 2>&1 | grep Duration

  Duration : 00:00:04.00, start : 0.000000, bitrate : 3228 kb/s

  Duration : 00:00:01.00, start : 0.000000, bitrate : 23132 kb/s

  Duration : 00:00 :39.98, start : 0.000000, bitrate : 910 kb/s

  Why am I not getting an exact result of 5 seconds, but instead a much larger value ?

• ffmpeg - duration usage in input text file

  12 mai 2018, par Voicu

  I am trying to use ffmpeg to concatenate video segments with some black screen. To do that I’ve first generated a blank 10-second video (no audio track) with :

  $ ffmpeg -f lavfi -i color=black:s=320x240:r=1 -f lavfi -i anullsrc -t 10 -vcodec libvpx -an blank.mkv

  I then created the simplest possible scenario within input.txt file (contents below) in order to have three seconds of black screen followed by some video (no audio track) :

  file 'blank.mkv'
  
  duration 3
  
  file 'video_example.mkv'

  And, finally, ran the following ffmpeg command to concat the contents of that input file :

  $ ffmpeg -f concat -i input.txt -codec:v copy -codec:a copy output.mkv

  The issue that I have is that the duration 3 is not considered, so the final video still has ten seconds of black frames (instead of three) followed by my video. And also "Non-monotonous DTS in output stream 0:0 ..." message is shown when using duration x in the file. If I remove duration the warnings are gone and getting the 10-second black screen first output as well.

  Full output of the ffmpeg concat command :

  $ ffmpeg -hide_banner -f concat -i input.txt -codec:v copy -codec:a copy output.mkv
  
  Input #0, concat, from 'input.txt':
  
    Duration: N/A, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: vp8, yuv420p(progressive), 320x240, SAR 1:1 DAR 4:3, 1 fps, 1 tbr, 1k tbn, 1k tbc
  
      Metadata:
  
        ENCODER         : Lavc57.107.100 libvpx
  
        DURATION        : 00:00:10.000000000
  
  File 'output.mkv' already exists. Overwrite ? [y/N] y
  
  Output #0, matroska, to 'output.mkv':
  
    Metadata:
  
      encoder         : Lavf57.83.100
  
      Stream #0:0: Video: vp8 (VP80 / 0x30385056), yuv420p(progressive), 320x240 [SAR 1:1 DAR 4:3], q=2-31, 1 fps, 1 tbr, 1k tbn, 1k tbc
  
      Metadata:
  
        ENCODER         : Lavc57.107.100 libvpx
  
        DURATION        : 00:00:10.000000000
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [concat @ 000000000031a440] DTS 3000 < 9000 out of order
  
  [matroska @ 0000000000328420] Non-monotonous DTS in output stream 0:0; previous: 9000, current: 3000; changing to 9000. This may result in incorrect timestamps in the output file.
  
  [matroska @ 0000000000328420] Non-monotonous DTS in output stream 0:0; previous: 9000, current: 4001; changing to 9000. This may result in incorrect timestamps in the output file.
  
  [matroska @ 0000000000328420] Non-monotonous DTS in output stream 0:0; previous: 9000, current: 4998; changing to 9000. This may result in incorrect timestamps in the output file.
  
  [matroska @ 0000000000328420] Non-monotonous DTS in output stream 0:0; previous: 9000, current: 6004; changing to 9000. This may result in incorrect timestamps in the output file.
  
  [matroska @ 0000000000328420] Non-monotonous DTS in output stream 0:0; previous: 9000, current: 7002; changing to 9000. This may result in incorrect timestamps in the output file.
  
  [matroska @ 0000000000328420] Non-monotonous DTS in output stream 0:0; previous: 9000, current: 8005; changing to 9000. This may result in incorrect timestamps in the output file.
  
  frame= 5794 fps=0.0 q=-1.0 Lsize=    7109kB time=01:37:09.70 bitrate=  10.0kbits/s speed=5.16e+004x
  
  video:7043kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.926229%

  Any idea what am I doing wrong ? The warning seems to hint towards the issue here.

  Other possibly useful info :

  $ ffprobe -hide_banner blank.mkv
  
  Input #0, matroska,webm, from 'blank.mkv':
  
    Metadata:
  
      ENCODER         : Lavf57.83.100
  
    Duration: 00:00:10.00, start: 0.000000, bitrate: 1 kb/s
  
      Stream #0:0: Video: vp8, yuv420p(progressive), 320x240, SAR 1:1 DAR 4:3, 1 fps, 1 tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        ENCODER         : Lavc57.107.100 libvpx
  
        DURATION        : 00:00:10.000000000
  
  
  
  $ ffprobe -hide_banner video_example.mkv
  
  Input #0, matroska,webm, from 'video_example.mkv':
  
    Metadata:
  
      encoder         : GStreamer matroskamux version 1.8.1.1
  
      creation_time   : 2018-05-04T17:57:04.000000Z
  
    Duration: 01:37:08.70, start: 15434.269000, bitrate: 9 kb/s
  
      Stream #0:0(eng): Video: vp8, yuv420p(progressive), 320x240, SAR 1:1 DAR 4:3, 1 fps, 1 tbr, 1k tbn, 1k tbc (default)
  
      Metadata:
  
        title           : Video
  
  
  
  $ ffmpeg -v
  
  ffmpeg version 3.4.2 Copyright (c) 2000-2018 the FFmpeg developers
  
    built with gcc 7.3.0 (GCC)