[FFmpeg-trac] #3625(swscale:new): Unscaled conversion from yuv420p to gray is slow
FFmpeg
trac at avcodec.org
Fri May 9 08:18:36 CEST 2014
#3625: Unscaled conversion from yuv420p to gray is slow
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Reporter: andreasg | Owner:
Type: defect | Status: new
Priority: normal | Component: swscale
Version: git-master | Resolution:
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by andreasg):
Converting from yuv420p to grayscale without scaling pretty much just
requires copying the prefix bytes:
http://en.wikipedia.org/wiki/YUV#Y.27UV420p_.28and_Y.27V12_or_YV12.29_to_RGB888_conversion
I haven't looked at the implementation to see if that's what it's doing.
I also haven't checked the quality of the old output. I would like to
point out that converting from yuv420p to rgb is almost three times faster
than the current conversion to grayscale. I could write my own
implementation from YUV to grayscale but I would prefer not to have to
deal with all the different variants.
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Ticket URL: <https://trac.ffmpeg.org/ticket/3625#comment:2>
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