[FFmpeg-trac] #2845(undetermined:new): Introduce mechanism to extract image/video metadata without actually decoding frame data

[FFmpeg]

#2845: Introduce mechanism to extract image/video metadata without actually
decoding frame data
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             Reporter:  rmk          |                     Type:
               Status:  new          |  enhancement
            Component:               |                 Priority:  wish
  undetermined                       |                  Version:
             Keywords:               |  unspecified
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
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 Currently ffmpeg and all other tools relying on avformat_find_stream_info
 to extract metadata for some codecs always decode an entire frame in cases
 where theoretically this would not be necessary, examples being JPEG, PNG
 and TIFF but there are probably more. This makes avformat_find_stream_info
 very inefficient for that purpose in these cases (e.g. having to decode a
 20 megapixel jpg or a 400MB tiff image to find out the image dimensions is
 orders of magnitude slower than it could be if only headers were parsed).

 This was discussed on the mailing list in this thread including
 suggestions for a solution approach:

 http://ffmpeg-users.933282.n4.nabble.com/Probing-jpg-png-and-tiff-images-
 without-decoding-frames-td4660508.html

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2845>
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