[FFmpeg-trac] #6494(ffmpeg:new): Concat'ing HEVC streams with different encoding parameters produces gibberish

FFmpeg trac at avcodec.org
Wed Jun 28 01:37:30 EEST 2017


#6494: Concat'ing HEVC streams with different encoding parameters produces
gibberish
-------------------------------------+-------------------------------------
             Reporter:  birdie       |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  ffmpeg       |                  Version:  git-
             Keywords:  concat,      |  master
  hevc                               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug: after you concat two HEVC streams with '''different'''
 encoding parameters and you try to play the resulting file, when
 ffplay/mpv/mplayer reaches the second file, you see garbage instead of the
 actual output.

 How to reproduce:

 {{{
 The first file parameters:
 $ ffmpeg -i input1 -an -c:v libx265 -preset veryslow -x265-params crf=20
 :no-sao=1    file1.mkv

 The second file parameters:
 $ ffmpeg -i input2 -an -c:v libx265 -preset veryslow -tune grain
 -x265-params crf=20 file2.mkv

 $ cat list.txt
 file file1.mkv
 file file2.mkv

 Concat:
 $ ffmpeg -f concat -i list.txt -c copy out.mkv
 }}}

 When reaching the second part of the output multiple messages like this
 one are logged in console:
 {{{
 [ffmpeg/video] hevc: The cu_qp_delta -56 is outside the valid range [-26,
 25].
 }}}

 mkvtoolnix produces the same broken output.

 However if you first transcode the mkv files to TS and then concat the
 resulting ts files, then everything works fine:

 {{{
 $ ffmpeg -i part1.mkv -c copy output1.ts
 $ ffmpeg -i part2.mkv -c copy output2.ts
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/6494>
FFmpeg <https://ffmpeg.org>
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