[FFmpeg-trac] #5176(avcodec:new): avcodec_decode_video2 requiring input buffer to be larger than actual read bytes

[FFmpeg]

#5176: avcodec_decode_video2 requiring input buffer to be larger than actual read
bytes
-------------------------------------+-------------------------------------
             Reporter:  hbos         |                     Type:
               Status:  new          |  enhancement
            Component:  avcodec      |                 Priority:  normal
             Keywords:               |                  Version:
  avcodec_decode_video2              |  unspecified
  AV_INPUT_BUFFER_PADDING_SIZE       |               Blocked By:
  input buffer bitstream reader 32   |  Reproduced by developer:  0
  64 bits overread                   |
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 As is already known and documented by avcodec_decode_video2, the input
 buffer needs to be AV_INPUT_BUFFER_PADDING_SIZE larger than the actual
 read bytes because some bistream readers read 32 or 64 bits at once and
 can over-read.

 I view this as a flaw and suggest this is fixed so that you don't have to
 allocate more bytes than the encoded data. It shouldn't be a performance
 issue because you can still read in 64 (or whatever) bit chunks up 'til
 the very end.

 (As someone who is using multiple libraries, FFmpeg is now a special case
 when allocating buffers, and I feel like it shouldn't have to be.)

--
Ticket URL: <https://trac.ffmpeg.org/ticket/5176>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker