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

[FFmpeg]

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

Comment (by glopes):

 Sorry for that. You can download an example video from here:
 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.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2452#comment:2>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker