[FFmpeg-trac] #2151(swscale:closed): Warning: data is not aligned! This can lead to a speedloss

[FFmpeg]

#2151: Warning: data is not aligned! This can lead to a speedloss
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             Reporter:  viric   |                    Owner:  (none)
                 Type:  defect  |                   Status:  closed
             Priority:  normal  |                Component:  swscale
              Version:  1.1     |               Resolution:  invalid
             Keywords:          |               Blocked By:
             Blocking:          |  Reproduced by developer:  0
Analyzed by developer:  0       |
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Changes (by Niklas Haas):

 * resolution:   => invalid
 * status:  new => closed

Comment:

 I'm pretty sure this is an unavoidable consequence of cropping to an
 unaligned offset. There is nothing we can do about this except do a full
 memcpy into an aligned buffer, which I'm pretty sure will not help.

 swscale.c prints this message whenever the data pointers are not a
 multiple of 16, and since the yuv422p chroma plane is subsampled by a
 factor of 2 (in the horizontal direction), that means the chroma plane now
 starts at an offset of 8 (relative to the aligned image start).

 Closing since everything is "working as intended". The message is just
 letting you know that you are requesting a crop that will inevitably slow
 down scaling.
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Ticket URL: <https://trac.ffmpeg.org/ticket/2151#comment:3>
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