On 9/25/14, Dave Rice <[email protected]> wrote: > Hi all, > > This issue arose on the github issue tracker for QCTools > https://github.com/bavc/qctools/issues/36 (which is a GUI to utilize > ffmpeg's signalstats filter as well as apply certain filterchain's in video > playback to facilitate video analysis). Downloads here: > http://bavc.org/qctools > > Matthias supplied a yuvj420p h264 at > https://www.dropbox.com/s/gxv9ycr1lbmh0wu/70D_lumarange.mov?dl=0 and some > filters express the video in a range of 0-255 while others express it in a > range of ~16-235. > > To find the maximum Y value I can run it through signaltstats to get that > value: > > ffprobe -f lavfi movie=70D_lumarange.mov,signalstats -show_entries > frame_tags=lavfi.signalstats.YMAX > ffprobe version 2.3.3 Copyright (c) 2007-2014 the FFmpeg developers > built on Sep 22 2014 21:58:44 with Apple LLVM version 6.0 (clang-600.0.51) > (based on LLVM 3.5svn) > configuration: --prefix=/usr/local/Cellar/ffmpeg/2.3.3 --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-libfreetype --enable-ffplay > --enable-libopenjpeg --disable-decoder=jpeg2000 > --extra-cflags='-I/usr/local/Cellar/openjpeg/1.5.1_1/include/openjpeg-1.5 ' > libavutil 52. 92.100 / 52. 92.100 > libavcodec 55. 69.100 / 55. 69.100 > libavformat 55. 48.100 / 55. 48.100 > libavdevice 55. 13.102 / 55. 13.102 > libavfilter 4. 11.100 / 4. 11.100 > libavresample 1. 3. 0 / 1. 3. 0 > libswscale 2. 6.100 / 2. 6.100 > libswresample 0. 19.100 / 0. 19.100 > libpostproc 52. 3.100 / 52. 3.100 > [swscaler @ 0x7fa4b2004a00] deprecated pixel format used, make sure you did > set range correctly > Input #0, lavfi, from 'movie=70D_lumarange.mov,signalstats': > Duration: N/A, start: 0.000000, bitrate: N/A > Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 1280x720 [SAR > 1:1 DAR 16:9], 50 fps, 50 tbr, 50k tbn, 50k tbc > [FRAME] > TAG:lavfi.signalstats.YMAX=235 > [/FRAME] > [...] > > But if I run the video through the histogram filter such as: > > ffplay 70D_lumarange.mov -vf > "histogram=mode=waveform:waveform_mode=column:waveform_mirror=1,crop=iw:256:0:0" > > then the output video shows values plotted for the entire 0-255 range > implying that YMAX the greater y value per frame) should actually equal 255. > Obviously one filter is incorrect or there is distinct extra processing that > affects yuvj material between these two commands that I would like to > change.
signalstats filter does not support yuvJ formats but histogram filter in waveform mode does. > > I've tried playing with -color_range before and after the input to no > affect, but I am trying to figure out what the actual maximum Y value is > for the sample file and then how to get each filter (signalstats and > histogram) to show that result consistently. > > Thanks much, > Dave Rice > > > _______________________________________________ > ffmpeg-user mailing list > [email protected] > http://ffmpeg.org/mailman/listinfo/ffmpeg-user > _______________________________________________ ffmpeg-user mailing list [email protected] http://ffmpeg.org/mailman/listinfo/ffmpeg-user
