[FFmpeg-trac] #6381(ffmpeg:new): Re-encoding png image fails

[FFmpeg]

#6381: Re-encoding png image fails
----------------------------------+--------------------------------------
             Reporter:  guest123  |                     Type:  defect
               Status:  new       |                 Priority:  normal
            Component:  ffmpeg    |                  Version:  git-master
             Keywords:  png       |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
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 **Summary of the bug:** Sometimes Ffmpeg fails to re-encode png file which
 is correct according to the png file formet specification.

 **How to reproduce:** Try to re-encode this file
 [https://github.com/guest161373/1/blob/master/1.hex] (it is a valid png
 file):
 {{{
 ffmpeg -i 1.hex -y 2.png
 }}}
 Output of Ffmpeg is
 {{{
 [png @ 0000000000574520] inflate returned error -3
 Input #0, png_pipe, from '1.hex':
   Duration: N/A, bitrate: N/A
     Stream #0:0: Video: png, rgb24(pc), 2400x1500 [SAR 3779:3779 DAR 8:5],
 25 tbr, 25 tbn, 25 tbc
 Output #0, image2, to '1.png':
   Metadata:
     encoder         : Lavf57.57.100
     Stream #0:0: Video: png, rgb24, 2400x1500 [SAR 3779:3779 DAR 8:5],
 q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
     Metadata:
       encoder         : Lavc57.66.101 png
 Stream mapping:
   Stream #0:0 -> #0:0 (png (native) -> png (native))
 Press [q] to stop, [?] for help
 [png @ 00000000005658e0] inflate returned error -3
 Error while decoding stream #0:0: Generic error in an external library
 frame=    0 fps=0.0 q=0.0 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=
 0x
 video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
 muxing overhead: unknown
 Output file is empty, nothing was encoded (check -ss / -t / -frames
 parameters if used)
 Conversion failed!
 }}}
 All other png encoders/decoders can process this file correctly. This is
 how the image should look like: [https://i.imgur.com/Zp0Eau4.png]

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Ticket URL: <https://trac.ffmpeg.org/ticket/6381>
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