[FFmpeg-trac] #225(undetermined:open): Converting from YUVJ to YUV lose contrast

FFmpeg trac at avcodec.org
Sat May 21 09:51:24 CEST 2011

#225: Converting from YUVJ to YUV lose contrast
Reporter:  sghpunk            |       Owner:
    Type:  defect             |      Status:  open
Priority:  normal             |   Component:  undetermined
 Version:  git-master         |  Resolution:
Keywords:  YUV/YUVJ contrast  |  Blocked By:
Blocking:                     |  Reproduced:  0
Analyzed:  0                  |

Comment (by sghpunk):

 I do the same, as you described.
 And I can say... It is more complicated, than I thought...
 (ffmpeg -i out001.jpg out.png) - No differences, as you say.
 And here (ffmpeg -i out001.jpg -qscale 2 out.avi) begins a ... gm ...
 magic ))
 When I play out.avi with mplayer2 (http://www.mplayer2.org/), there is
 difference between jpg and avi (avi is less contrast), but when I play
 out.avi with KMplayer, there is no contrast differences... Only little
 white balance, but it is not so important.
 So. I don't understand, maybe it is mlayer2 bug, or ffmpeg bug but not in
 that place that I thought. (Because mplayer2 use the same ffmpeg for
 decoding video).
 I attached a screenshot with two opened mplayer2 windows (left - input
 file with normal contrast, right - output file with low contrast), seems
 like on this screenshot contrast differences looks good. (If not, you can
 in gimp test a color value in same white places on image, and see the
 But I still cannot understand, why when i use yuv4mpeg raw file for
 encoding there is no contrast differences in mplayer2.

 About compiler options, I not test it so deep, I do this later, and maybe
 you can recommend what test I can perform to be sure is  that options
 efficient or not.

Ticket URL: <https://avcodec.org/trac/ffmpeg/ticket/225#comment:6>
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