[FFmpeg-trac] #6333(avformat:open): ffplay returns error in case of flac picture data error

FFmpeg trac at avcodec.org
Sun Oct 6 06:52:22 EEST 2019

#6333: ffplay returns error in case of flac picture data error
             Reporter:  mikhailnov   |                    Owner:
                 Type:  defect       |                   Status:  open
             Priority:  important    |                Component:  avformat
              Version:  git-master   |               Resolution:
             Keywords:  flac         |               Blocked By:
  regression                         |
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  0            |

Comment (by mkver):

 1. The length field for flac metadata blocks is 3 bytes long. A
 METADATA_BLOCK_PICTURE has its own length field for the length of the
 binary data and said field is four bytes long. These fields are 0x02C66B
 and 0x0102C642 and they are consistent in the sense that the implied
 length of the picture given by the metadata block picture size agrees with
 the lower 24 bits of the picture data length field.
 2. Afterwards lots of picture data gets shoved into the parser and runs
 afoul of a check designed to tackle invalid data. As a result of said
 check, new data (that is valid flac) doesn't even get looked for sync
 codes at all.

Ticket URL: <https://trac.ffmpeg.org/ticket/6333#comment:6>
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