[FFmpeg-trac] #9088(undetermined:new): HEVC bitstream with alpha layer to mp4

FFmpeg trac at avcodec.org
Mon Feb 1 21:45:30 EET 2021

#9088: HEVC bitstream with alpha layer to mp4
             Reporter:  johnhe4      |                     Type:
                                     |  enhancement
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:  hevc h.265   |               Blocked By:
  alpha transparency missing access  |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
 == Summary ==

 I used NVIDIA's Video Codec SDK to create an HEVC bitstream containing an
 alpha layer. I tried to mux this bitstream into an MP4 container with no
 success. I was hoping this would work because:
  1. It was a copy, not a re-encode (no need to involve libx265)
  2. This change gave me hope:

 No cigar. FFmpeg ''did'' create an MP4 file but the MP4 will not play in
 QuickTime and does not seem to retain the alpha layer.  Whenever a
 `nuh_layer_id > 0` is encountered FFmpeg outputs:
 {{{ missing picture in access unit }}}

 I've attached the `ffmpeg -v trace ...` output to this request as well as
 the HEVC bitstream containing the alpha layer.

 == How to reproduce ==

 % ffmpeg -i bsWithAlpha.265 -c:v copy -tag:v hvc1 outputWithAlpha.mp4

Ticket URL: <https://trac.ffmpeg.org/ticket/9088>
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