[FFmpeg-trac] #2452(undetermined:reopened): decoding yuv420p to rgb shifts luminance down

[FFmpeg]

#2452: decoding yuv420p to rgb shifts luminance down
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             Reporter:  burek        |                    Owner:
                 Type:  defect       |                   Status:  reopened
             Priority:  normal       |                Component:
              Version:  unspecified  |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
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Changes (by glopes):

 * status:  closed => reopened
 * resolution:  needs_more_info =>


Comment:

 I'm really sorry for not being able to retry the example with the new
 modified FFmpeg sources, but to say that there is no input sample is not
 true!

 It's in the first comment, I'll repost below. If someone could please just
 run this video through the patch would be super helpful...

  https://dl.dropboxusercontent.com/u/3907539/video.avi
 Running the following commandline produces a bitmap with the correct
 luminance values:
 ffmpeg -ss 0.5 -i video.avi -vframes 1 -t 1 -s 1280x680 -pix_fmt gray
 gray.bmp
 Running the following commandline produces a bitmap in which the luminance
 values are shifted ~10 values darker:
 ffmpeg -ss 0.5 -i video.avi -vframes 1 -t 1 -s 1280x680 -pix_fmt bgr24
 rgb.bmp
 Also playing this video file in VLC produces the correct luminance values.
 The video was acquired from a grayscale camera and encoded as grayscale
 pixel format to mpeg4 yuv420p using FFMPEG (as you can see from the
 commandline output shown in the original ticket).
 Hope this helps to clarify the issue.

 I can't seem to modify the original description of the ticket or else I
 would include it in there...

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2452#comment:14>
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