[FFmpeg-trac] #9535(undetermined:new): PNG decoder fails processing more than a certain number of frames

FFmpeg trac at avcodec.org
Sat Nov 27 20:59:01 EET 2021

#9535: PNG decoder fails processing more than a certain number of frames
             Reporter:  panthalassa  |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:
  undetermined                       |  unspecified
             Keywords:  png          |               Blocked By:
  decoding                           |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
 Summary of the bug: trying to encode a video with more than a certain
 number of frames from a .png sequence results in corrupted output and an
 out-of-memory scenario

 How to reproduce:
 Sorry but due to the absurd bandwith requirements I likely won't be able
 to upload the offending files. This can likely be reproduced by converting
 a long, losslessly compressed video into a sufficient number of PNG's (my
 stats: 11 minute 1080p video at 60fps = ~39,000 frames, each frame 1.9mb
 making the uncompressed video around 80gb) I acquired these frames from
 rendering in Blender

 Present on all versions I've tested from 3.4.8 to 4.4.1. Any png-based
 input fails with too many files in the directory - symptoms include the
 encoded video having scrambled frame order after about 1000 frames, as
 well as the [png @ 0x??? chunk too big] error after about 14750 processed

 Taking a generous swathe of images around the error points and processing
 them separately produces no errors implying that a corrupted PNG is not to

 Putting a smaller (1-2000) number of frames in a directory and processing
 them separately produces a successful result longer than 1000 frames, past
 the previous point of onset for corruption. Unknown exactly how many
 frames are needed to cause the error.

 Any format encoding that receiving raw PNG input appears to be bugged -
 libx264rgb, libx265, ffv1 tested

 Latest tested version: clean install of N-104671-g2cddb2f7a8 on a live USB
 of Linux Mint 19.1 MATE following the instructions on the Compile FFMPEG

 % ffmpeg -framerate 60 -f image2 -pattern_type glob -i $1'/*.png' -vcodec
 libx265 -pix_fmt yuv420p10le -vf scale=out_range=pc $2

 % ffmpeg -framerate 60 -f image2 -pattern_type glob -i $1'/*.png' -vcodec
 ffv1 -coder 1 -level 3 -threads 4 -slices 4 -pix_fmt bgra $2

 ffmpeg version: N-104671-g2cddb2f7a8
 built on ... Linux Mint 19.1 MATE live USB
Ticket URL: <https://trac.ffmpeg.org/ticket/9535>
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