• Anton Khirnov's avatar
    lavu/frame: deprecate AVFrame.pkt_{pos,size} · 27f8c9b2
    Anton Khirnov authored
    These fields are supposed to store information about the packet the
    frame was decoded from, specifically the byte offset it was stored at
    and its size.
    
    However,
    - the fields are highly ad-hoc - there is no strong reason why
      specifically those (and not any other) packet properties should have a
      dedicated field in AVFrame; unlike e.g. the timestamps, there is no
      fundamental link between coded packet offset/size and decoded frames
    - they only make sense for frames produced by decoding demuxed packets,
      and even then it is not always the case that the encoded data was
      stored in the file as a contiguous sequence of bytes (in order for pos
      to be well-defined)
    - pkt_pos was added without much explanation, apparently to allow
      passthrough of this information through lavfi in order to handle byte
      seeking in ffplay. That is now implemented using arbitrary user data
      passthrough in AVFrame.opaque_ref.
    - several filters use pkt_pos as a variable available to user-supplied
      expressions, but there seems to be no established motivation for using them.
    - pkt_size was added for use in ffprobe, but that too is now handled
      without using this field. Additonally, the values of this field
      produced by libavcodec are flawed, as described in the previous
      ffprobe conversion commit.
    
    In summary - these fields are ill-defined and insufficiently motivated,
    so deprecate them.
    27f8c9b2
vf_crop.c 13.5 KB