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

[FFmpeg]

#225: Converting from YUVJ to YUV lose contrast
-------------------------------------+-------------------------------------
             Reporter:  sghpunk      |                    Owner:
                 Type:  defect       |                   Status:  reopened
             Priority:  normal       |                Component:  swscale
              Version:  git-master   |               Resolution:
             Keywords:  YUV/YUVJ     |               Blocked By:
  contrast                           |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Changes (by dtombs):

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


Comment:

 I can no longer reproduce this using H.264 as it seems ffmpeg supports
 yuvj for H.264 now and no conversion is done.

 I ''can'' however reproduce by transcoding to VP8 with the following
 command line:

 {{{
 ffmpeg -threads 2 -an -i yuvj_input.mkv -vb 1k -y webm-low_contrast.webm >
 enc_webm.log 2>&1
 }}}

 which produces the following output:

 {{{
 ffmpeg version 0.10.7-6:0.10.7-0jon1~raring Copyright (c) 2000-2013 the
 FFmpeg developers
   built on Jul 15 2013 21:27:34 with gcc 4.7.3
   configuration: --arch=amd64 --disable-stripping --enable-pthreads
 --enable-runtime-cpudetect --extra-version='6:0.10.7-0jon1~raring'
 --libdir=/usr/lib/x86_64-linux-gnu --prefix=/usr --enable-bzlib --enable-
 libdc1394 --enable-libfreetype --enable-frei0r --enable-gnutls --enable-
 libgsm --enable-libmp3lame --enable-librtmp --enable-libopencv --enable-
 libopenjpeg --enable-libpulse --enable-libschroedinger --enable-libspeex
 --enable-libtheora --enable-vaapi --enable-vdpau --enable-libvorbis
 --enable-libvpx --enable-zlib --enable-gpl --enable-postproc --enable-
 libcdio --enable-x11grab --enable-libx264 --shlibdir=/usr/lib/x86_64
 -linux-gnu --enable-shared --disable-static
   libavutil      51. 35.100 / 51. 35.100
   libavcodec     53. 61.100 / 53. 61.100
   libavformat    53. 32.100 / 53. 32.100
   libavdevice    53.  4.100 / 53.  4.100
   libavfilter     2. 61.100 /  2. 61.100
   libswscale      2.  1.100 /  2.  1.100
   libswresample   0.  6.100 /  0.  6.100
   libpostproc    52.  0.100 / 52.  0.100
 Input #0, matroska,webm, from 'yuvj_input.mkv':
   Metadata:
     MAKER           : NIKON CORPORATION
     MODEL           : NIKON D90
     CREATION_TIME   : 2011-05-05 07:47:28
     ENCODER         : Lavf53.0.3
   Duration: 00:00:05.04, start: 0.000000, bitrate: 14463 kb/s
     Stream #0:0: Video: mjpeg, yuvj422p, 1280x720, SAR 1:1 DAR 16:9, 24
 fps, 24 tbr, 1k tbn, 1k tbc (default)
 Incompatible pixel format 'yuvj422p' for codec 'libvpx', auto-selecting
 format 'yuv420p'
 [buffer @ 0x181a420] w:1280 h:720 pixfmt:yuvj422p tb:1/1000000 sar:1/1
 sws_param:
 [buffersink @ 0x1819f40] auto-inserting filter 'auto-inserted scale 0'
 between the filter 'src' and the filter 'out'
 [scale @ 0x181f080] w:1280 h:720 fmt:yuvj422p -> w:1280 h:720 fmt:yuv420p
 flags:0x4
 [libvpx @ 0x182bf20] v1.1.0
 Output #0, webm, to 'webm-low_contrast.webm':
   Metadata:
     MAKER           : NIKON CORPORATION
     MODEL           : NIKON D90
     CREATION_TIME   : 2011-05-05 07:47:28
     encoder         : Lavf53.32.100
     Stream #0:0: Video: vp8, yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--
 1, 1 kb/s, 1k tbn, 24 tbc (default)
 Stream mapping:
   Stream #0:0 -> #0:0 (mjpeg -> libvpx)
 Press [q] to stop, [?] for help
 frame=  121 fps=  9 q=0.0 Lsize=     187kB time=00:00:05.04 bitrate=
 304.5kbits/s
 video:186kB audio:0kB global headers:0kB muxing overhead 0.701462%
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/225#comment:18>
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