[FFmpeg-user] preserving YUV color range of 0-255

[Dave Rice]

On Mar 7, 2014, at 12:37 PM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:
> Dave Rice <dave <at> dericed.com> writes:
> 
>> Given that the test pattern has U and V at 128 I 
>> would expect these two commands to give the same results:
>> 
>> ffplay 256shades_ntsc.mov 
>> -vf 'histogram=mode=waveform:waveform_mode=column'
>> ffplay 256shades_ntsc.mov 
>> -vf 'extractplanes=y,histogram=mode=waveform:waveform_mode=column'
> 
> Is the problem you see reproducible with ffmpeg?
> 
> ffplay is an application that depends on an external 
> library that is known to contain bugs, so if the 
> problem is reproducible with ffmpeg, please explain 
> how.
> (Ideally, command line and complete, uncut console 
> output.)

Yes, the issue is the same via ffmpeg.

Here is the output when using histogram=mode=waveform:waveform_mode=column on a source that uses full range YUV.

ffmpeg -i 256shades_ntsc.mov -vf 'histogram=mode=waveform:waveform_mode=column' -frames:v 1 -y histogram_only.jpg
ffmpeg version 2.2.git Copyright (c) 2000-2014 the FFmpeg developers
  built on Mar  6 2014 20:43:26 with Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --enable-vda --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid --enable-ffplay
  libavutil      52. 66.101 / 52. 66.101
  libavcodec     55. 52.102 / 55. 52.102
  libavformat    55. 33.101 / 55. 33.101
  libavdevice    55. 11.100 / 55. 11.100
  libavfilter     4.  3.100 /  4.  3.100
  libavresample   1.  2.  0 /  1.  2.  0
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 18.100 /  0. 18.100
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '256shades_ntsc.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf55.19.102
  Duration: 00:00:00.03, start: 0.000000, bitrate: 164836 kb/s
    Stream #0:0(eng): Video: rawvideo (2vuy / 0x79757632), uyvy422, 720x486, 167793 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc (default)
    Metadata:
      handler_name    : DataHandler
[swscaler @ 0x7fa1e3000000] deprecated pixel format used, make sure you did set range correctly
Output #0, image2, to 'histogram_only.jpg':
  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf55.33.101
    Stream #0:0(eng): Video: mjpeg, yuvj422p, 720x768 [SAR 1:1 DAR 15:16], q=2-31, 200 kb/s, 90k tbn, 29.97 tbc (default)
    Metadata:
      handler_name    : DataHandler
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo -> mjpeg)
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=4.0 Lsize=N/A time=00:00:00.03 bitrate=N/A    
video:20kB audio:0kB subtitle:0 data:0 global headers:0kB muxing overhead -100.106201%

The resulting file is here http://dericed.com/media/extractplanes_then_histogram.jpg. It shows essentially a diagonal line in the Y plane representing values 0-255.

Here is the output for the same command as above but adding extractplanes=y at the beginning of the filterchain:

ffmpeg -i 256shades_ntsc.mov -vf 'extractplanes=y,histogram=mode=waveform:waveform_mode=column' -frames:v 1 -y extractplanes_then_histogram.jpg
ffmpeg version 2.2.git Copyright (c) 2000-2014 the FFmpeg developers
  built on Mar  6 2014 20:43:26 with Apple LLVM version 5.0 (clang-500.2.79) (based on LLVM 3.3svn)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/HEAD --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --enable-vda --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid --enable-ffplay
  libavutil      52. 66.101 / 52. 66.101
  libavcodec     55. 52.102 / 55. 52.102
  libavformat    55. 33.101 / 55. 33.101
  libavdevice    55. 11.100 / 55. 11.100
  libavfilter     4.  3.100 /  4.  3.100
  libavresample   1.  2.  0 /  1.  2.  0
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 18.100 /  0. 18.100
  libpostproc    52.  3.100 / 52.  3.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '256shades_ntsc.mov':
  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf55.19.102
  Duration: 00:00:00.03, start: 0.000000, bitrate: 164836 kb/s
    Stream #0:0(eng): Video: rawvideo (2vuy / 0x79757632), uyvy422, 720x486, 167793 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 30k tbc (default)
    Metadata:
      handler_name    : DataHandler
[swscaler @ 0x7fb7e8812400] deprecated pixel format used, make sure you did set range correctly
Output #0, image2, to 'extractplanes_then_histogram.jpg':
  Metadata:
    major_brand     : qt  
    minor_version   : 512
    compatible_brands: qt  
    encoder         : Lavf55.33.101
    Stream #0:0(eng): Video: mjpeg, yuvj444p, 720x768 [SAR 1:1 DAR 15:16], q=2-31, 200 kb/s, 90k tbn, 29.97 tbc (default)
    Metadata:
      handler_name    : DataHandler
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo -> mjpeg)
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=4.0 Lsize=N/A time=00:00:00.03 bitrate=N/A    
video:27kB audio:0kB subtitle:0 data:0 global headers:0kB muxing overhead -100.080383%

And here is the resulting image http://dericed.com/media/histogram_only.jpg. Instead of the diagonal line as before the values from 0-15 and 236-255 are crushed to the same value.
Best Regards,
Dave Rice