[FFmpeg-user] HD > SD Down-Convert Prores Color

Wed May 13 12:09:43 CEST 2015

> To: ffmpeg-user at ffmpeg.org
> From: cehoyos at ag.or.at
> Date: Wed, 13 May 2015 09:07:22 +0000
> Subject: Re: [FFmpeg-user] HD > SD Down-Convert Prores Color
> 
> Kevin Wells <kevwells <at> hotmail.co.uk> writes:
> 
> > Hi Carl, Is everything OK with my instructions on 
> > how to reproduce this issue?
> 
> No, FCP is not exactly a requirement for FFmpeg development.
> 
> I tested the following:
> $ ffmpeg -i HD_Source.mov 
> -vf colormatrix=bt709:bt601,scale=720:576:flags=lanczos 
> -vcodec prores out.mov
> $ ffmpeg -i out.mov -f rawvideo out1
> 
> I then compared the output file out1 with the following 
> file (the color filter defaults to black):
> $ ffmpeg -f lavfi -i color -pix_fmt yuv422p10 
> -f rawvideo -vframes 1 out2
> 
> The luminance of the files is very similar. Are you 
> reporting different chrominance values for zero 
> luminance?
> 
> Carl Eugen
> 
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Hi Carl, what platform are you using, Windows, Mac? In any application if you open the video and turn the gamma up you will see big problems. If you open the resulting video (SD_BARS.mov) up in Photoshop, goto Image, Adjustments, Exposure and turn the gamma right up (pull the slider right down) you will see big problems. I have attached all files used in this test, HD_BARS.mov (2 frame HD file), SD_BARS.mov (2 frame SD file) and two screen grabs, one of the untouched SD_BARS.mov and one with the gamma turned right up SD_BARS.mov, so you can see the massive problems using this line of code.
ffmpeg -i HD_BARS.mov -map 0:v -vf colormatrix=bt709:bt601,scale=720:576:flags=lanczos -vcodec prores_ks -profile:v 3 -vtag apch -vendor ap10 -pix_fmt yuv422p10le -f mov SD_BARS.mov
Heres the full output:

ffmpeg -i /Volumes/Kevs_GRAID/EXPORTS/HD_BARS.mov -map 0:v -vf colormatrix=bt709:bt601,scale=720:576:flags=lanczos -vcodec prores_ks -profile:v 3 -vtag apch -vendor ap10 -pix_fmt yuv422p10le -f mov /Volumes/Kevs_GRAID/EXPORTS/SD_BARS.movffmpeg version 2.6.2-tessus Copyright (c) 2000-2015 the FFmpeg developers  built with Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)  configuration: --cc=/usr/bin/clang --prefix=/Users/helmutt/data/ext/ffmpeg/sw --as=yasm --extra-version=tessus --disable-shared --enable-static --disable-ffplay --enable-gpl --enable-pthreads --enable-postproc --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libx265 --enable-libxvid --enable-libspeex --enable-bzlib --enable-zlib --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libxavs --enable-libsoxr --enable-libwavpack --enable-version3 --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvpx --enable-libgsm --enable-libopus --enable-libmodplug --enable-fontconfig --enable-libfreetype --enable-libass --enable-libbluray --enable-filters --disable-indev=qtkit --disable-indev=x11grab_xcb --enable-runtime-cpudetect  libavutil      54. 20.100 / 54. 20.100  libavcodec     56. 26.100 / 56. 26.100  libavformat    56. 25.101 / 56. 25.101  libavdevice    56.  4.100 / 56.  4.100  libavfilter     5. 11.102 /  5. 11.102  libswscale      3.  1.101 /  3.  1.101  libswresample   1.  1.100 /  1.  1.100  libpostproc    53.  3.100 / 53.  3.100Guessed Channel Layout for  Input Stream #0.1 : stereoInput #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Volumes/Kevs_GRAID/EXPORTS/HD_BARS.mov':  Metadata:    major_brand     : qt      minor_version   : 537199360    compatible_brands: qt      creation_time   : 2015-05-13 10:03:06  Duration: 00:00:00.08, start: 0.000000, bitrate: 17272 kb/s    Stream #0:0(eng): Video: prores (apch / 0x68637061), yuv422p10le(bt709), 1920x1080, 15360 kb/s, SAR 1:1 DAR 16:9, 25 fps, 25 tbr, 25 tbn, 25 tbc (default)    Metadata:      creation_time   : 2015-05-13 10:03:06      handler_name    : Apple Alias Data Handler      encoder         : Apple ProRes 422 HQ      timecode        : 00:00:00:00    Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, 2 channels, s16, 1536 kb/s (default)    Metadata:      creation_time   : 2015-05-13 10:03:06      handler_name    : Apple Alias Data Handler    Stream #0:2(eng): Data: none (tmcd / 0x64636D74), 0 kb/s (default)    Metadata:      creation_time   : 2015-05-13 10:03:06      handler_name    : Apple Alias Data Handler      timecode        : 00:00:00:00File '/Volumes/Kevs_GRAID/EXPORTS/SD_BARS.mov' already exists. Overwrite ? [y/N] yOutput #0, mov, to '/Volumes/Kevs_GRAID/EXPORTS/SD_BARS.mov':  Metadata:    major_brand     : qt      minor_version   : 537199360    compatible_brands: qt      encoder         : Lavf56.25.101    Stream #0:0(eng): Video: prores (prores_ks) (apch / 0x68637061), yuv422p10le, 720x576 [SAR 64:45 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 12800 tbn, 25 tbc (default)    Metadata:      creation_time   : 2015-05-13 10:03:06      handler_name    : Apple Alias Data Handler      timecode        : 00:00:00:00      encoder         : Lavc56.26.100 prores_ksStream mapping:  Stream #0:0 -> #0:0 (prores (native) -> prores (prores_ks))Press [q] to stop, [?] for helpframe=    2 fps=0.0 q=0.0 Lsize=      83kB time=00:00:00.08 bitrate=8520.4kbits/s    video:82kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.704545%

Kind regards.

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