[FFmpeg-trac] #4746(avcodec:new): prores alpha blending results in opaque rectangle

[FFmpeg]

#4746: prores alpha blending results in opaque rectangle
-------------------------------------+-------------------------------------
             Reporter:               |                     Type:  defect
  projectsymphony                    |                 Priority:  normal
               Status:  new          |                  Version:  git-
            Component:  avcodec      |  master
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 The attached file is a prores 4444 with a particular decoding problem. The
 video has a logo fading from from black and then fading to black again.
 However lavc rather than fading back to black, shows an opaque square
 rectangle.

 {{{
 ffmpeg version N-73640-gae4c9dd Copyright (c) 2000-2015 the FFmpeg
 developers
   built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM
 3.5svn)
   configuration: --cc=clang --enable-debug --disable-optimizations
 --disable-yasm --disable-asm --enable-libfdk-aac --enable-version3
 --enable-nonfree --enable-gpl --disable-doc --enable-libmp3lame --enable-
 openssl --enable-libfreetype --enable-avresample --enable-libopenjpeg
 --enable-libx264
   libavutil      54. 28.100 / 54. 28.100
   libavcodec     56. 47.100 / 56. 47.100
   libavformat    56. 40.100 / 56. 40.100
   libavdevice    56.  4.100 / 56.  4.100
   libavfilter     5. 21.100 /  5. 21.100
   libavresample   2.  1.  0 /  2.  1.  0
   libswscale      3.  1.101 /  3.  1.101
   libswresample   1.  2.100 /  1.  2.100
   libpostproc    53.  3.100 / 53.  3.100
 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'proresalphablock.mov':
   Metadata:
     major_brand     : qt
     minor_version   : 512
     compatible_brands: qt
     creation_time   : 2015-07-09 05:29:21
     encoder         : Lavf56.21.0
   Duration: 00:00:09.43, start: 0.031833, bitrate: 13066 kb/s
     Stream #0:0(eng): Video: prores (ap4h / 0x68347061), yuva444p10le,
 1920x1080, 13066 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 24k tbc (default)
     Metadata:
       creation_time   : 2015-07-09 05:29:21
       handler_name    : DataHandler
       encoder         : Apple ProRes 4444
 }}}

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Ticket URL: <https://trac.ffmpeg.org/ticket/4746>
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