[FFmpeg-trac] #9939(avcodec:new): JPEG 2000 images are decoded twice and needlessly slow

FFmpeg trac at avcodec.org
Fri Sep 23 18:17:17 EEST 2022

#9939: JPEG 2000 images are decoded twice and needlessly slow
             Reporter:  Tomas Härdin  |                    Owner:  (none)
                 Type:  enhancement   |                   Status:  new
             Priority:  wish          |                Component:  avcodec
              Version:  git-master    |               Resolution:
             Keywords:  j2k           |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
Comment (by Tomas Härdin):

 Replying to [comment:1 mkver]:
 > As I have already told you on IRC: The jpeg2000 decoder needs to set the
 FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM cap internal (and needs to export the
 relevant info even if the frame is discarded due to skip_frame being to
 set to AVDISCARD_ALL). Then the frame won't be decoded in
 I implemented a very hackish solution like this and it does indeed work.
 Basically jpeg2000_read_main_headers(), ff_thread_get_buffer(), cleanup
 and then returning. I'm using pngdec.c as my reference.
Ticket URL: <https://trac.ffmpeg.org/ticket/9939#comment:3>
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