On Sun, 22 Oct 2023 at 00:39, pehache <pehach...@gmail.com> wrote: > > Hello, > > I have trouble converting a 4K HDR video into a HD SDR one. Basically it > plays much too dark and reddish in VLC (on macOS). The ffprobe output is > this video is at the bottom of the post > > I first tried applying a curve filter to boost the dark tones. I works > not too bad, but the reddish shift is still, if not amplified. > > Then I browsed the web and found a filter set that looks popular (I mean > copied/pasted on many different pages): > > -vf zscale=t=linear:npl=100,format=gbrpf32le,zscale=p=bt709, \ > tonemap=tonemap=hable,zscale=t=bt709:m=bt709:r=tvformat=yuv420p > > But, well, it doesn't solve anything... Using "gamma" instead of "hable" > gives a higher luminosity, but there's still a strong red shift. > > I tried many different things with the zscale filter, but the problem is > that I don't fully understand the effect of the different parameters, > although I'm not completly unfamiliar with the color profiles. It seems > to me that all of this deals mainly the luminosity, and little with the > chrominance. > > I have also found a page that describes how to convert from the bt.2020 > to bt709 profile, with a link to download a LUT file. > https://www.binarytides.com/color-grading-hlg-videos-with-ffmpeg/ > https://nopixels.net/articles/hlg-to-rec709/ > > So I tried the filter lut3d=nopixels_net_hlg2020_to_rec709.cube, with > various combinations of the zscale filter, but could not obtain anything > correct at the end. I always have reddish, or very reddish, or pinkish, > color shifts... > > > I'm a bit lost, now... Any help appreciated ! > > > > =============================================================== > *****$ ffprobe in0.mkv > ffprobe version 4.4.4 Copyright (c) 2007-2023 the FFmpeg developers > built with Apple LLVM version 9.1.0 (clang-902.0.39.2) > configuration: --prefix=/opt/local --cc=/usr/bin/clang > --mandir=/opt/local/share/man --enable-audiotoolbox --disable-indev=jack > --disable-libjack --disable-libopencore-amrnb > --disable-libopencore-amrwb --disable-libxcb --disable-libxcb-shm > --disable-libxcb-xfixes --enable-opencl --disable-outdev=xv > --enable-sdl2 --disable-securetransport --enable-videotoolbox > --enable-avfilter --enable-avresample --enable-fontconfig > --enable-gnutls --enable-libass --enable-libbluray --enable-libdav1d > --enable-libfreetype --enable-libfribidi --enable-libmodplug > --enable-libmp3lame --enable-libopenjpeg --enable-libopus > --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libtheora > --enable-libvorbis --enable-libvpx --enable-libzimg --enable-libzvbi > --enable-lzma --enable-pthreads --enable-shared --enable-swscale > --enable-zlib --enable-libaom --enable-libsvtav1 --arch=x86_64 > --enable-x86asm --enable-gpl --enable-libvidstab --enable-libx264 > --enable-libx265 --enable-libxvid --enable-postproc > libavutil 56. 70.100 / 56. 70.100 > libavcodec 58.134.100 / 58.134.100 > libavformat 58. 76.100 / 58. 76.100 > libavdevice 58. 13.100 / 58. 13.100 > libavfilter 7.110.100 / 7.110.100 > libavresample 4. 0. 0 / 4. 0. 0 > libswscale 5. 9.100 / 5. 9.100 > libswresample 3. 9.100 / 3. 9.100 > libpostproc 55. 9.100 / 55. 9.100 > Input #0, matroska,webm, from 'in0.mkv': > Metadata: > encoder : libebml v1.4.0 + libmatroska v1.6.2 > creation_time : 2021-03-09T20:53:48.000000Z > Writing frontend: StaxRip v1.7.0.3 > Duration: 00:49:10.18, start: 0.000000, bitrate: 4963 kb/s > Chapters: > [...] > Stream #0:0: Video: hevc (Main 10), yuv420p10le(tv, > bt2020nc/bt2020/smpte2084), 3840x2160, SAR 1:1 DAR 16:9, 23.98 fps, > 23.98 tbr, 1k tbn, 23.98 tbc (default) > Metadata: > BPS-eng : 4003363 > DURATION-eng : 00:49:09.197000000 > NUMBER_OF_FRAMES-eng: 70710 > NUMBER_OF_BYTES-eng: 1475838552 > _STATISTICS_WRITING_APP-eng: mkvmerge v50.0.0 ('Awakenings') 64-bit > _STATISTICS_WRITING_DATE_UTC-eng: 2021-03-09 20:53:48 > _STATISTICS_TAGS-eng: BPS DURATION NUMBER_OF_FRAMES NUMBER_OF_BYTES > [...] > > > Please provide a sample of the input file and uncut output of the ffmpeg command line in use. _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user
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