[FFmpeg-trac] #7599(avcodec:new): Add monochrome/gray pixel format to libaom-av1

FFmpeg trac at avcodec.org
Mon Jan 7 22:30:28 EET 2019


#7599: Add monochrome/gray pixel format to libaom-av1
-------------------------------------+-----------------------------------
             Reporter:  Ewout        |                    Owner:
                 Type:  enhancement  |                   Status:  new
             Priority:  wish         |                Component:  avcodec
              Version:  git-master   |               Resolution:
             Keywords:  libaom       |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by SmilingWolf):

 I digged a bit into this.

 It looks like libaom doesn't truly handle single planes and invariably
 expects 3 to be present, so when receiving a Cmono Y4M file in input it
 artificially creates the U and V planes filling them with 0x80:
 https://aomedia.googlesource.com/aom/+/2395ed028ca3a5a597cda74054440fd2d21330a3/common/y4minput.c#764

 If I understood correctly, FFmpeg with the gray pix_fmt hands a single Y
 plane to libaom, which subsequently chokes in
 https://aomedia.googlesource.com/aom/+/2395ed028ca3a5a597cda74054440fd2d21330a3/av1/encoder/extend.c#144
 because it tries to read invalid data

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Ticket URL: <https://trac.ffmpeg.org/ticket/7599#comment:3>
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