我有一些 4K HDR 视频，如果直接在非 HDR 设备（实际上使用 VLC）上播放，它们看起来会非常暗（并且偏红），这是一个已知问题。我尝试使用 ffmpeg 将其转换为 SDR，浏览网页时，许多页面上都会出现一个滤镜集，所以我就使用它了（只是添加了比例和锐化滤镜）：
ffmpeg -ss 75 -i in0.mkv -map 0:0 \
-vf scale=1280x720,unsharp,zscale=t=linear:npl=100,format=gbrpf32le,\
zscale=p=bt709,tonemap=tonemap=hable,zscale=t=bt709:m=bt709:r=tv,\
format=yuv420p -t 60 -y ou0.mkv
问题是，亮度只是高了一点，色调和输入视频一样。我对色彩空间等并不陌生，但我不太明白这个滤镜组应该做什么，以及应该怎么做才能得到预期的结果。
以下是 ffmpeg 的终端输出：
*****$ ffmpeg -ss 75 -i in0.mkv -map 0:0 -vf scale=1280x720,unsharp,zscale=t=linear:npl=100,format=gbrpf32le,zscale=p=bt709,tonemap=tonemap=hable,zscale=t=bt709:m=bt709:r=tv,format=yuv420p -t 60 -y ou0.mkv
ffmpeg version 4.4.4 Copyright (c) 2000-2023 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
[...]
Stream mapping:
Stream #0:0 -> #0:0 (hevc (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 0x7f9566801200] using SAR=1/1
[libx264 @ 0x7f9566801200] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0x7f9566801200] profile High, level 3.1, 4:2:0, 8-bit
[libx264 @ 0x7f9566801200] 264 - core 157 - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=23 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, matroska, to 'ou0.mkv':
Metadata:
Writing frontend: StaxRip v1.7.0.3
encoder : Lavf58.76.100
Chapters:
[...]
Stream #0:0: Video: h264 (H264 / 0x34363248), yuv420p(bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], q=2-31, 23.98 fps, 1k tbn (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
encoder : Lavc58.134.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
frame= 1431 fps= 13 q=-1.0 Lsize= 6532kB time=00:00:59.89 bitrate= 893.4kbits/s speed=0.551x
video:6520kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.177061%
[libx264 @ 0x7f9566801200] frame I:12 Avg QP:17.09 size: 45016
[libx264 @ 0x7f9566801200] frame P:365 Avg QP:20.47 size: 9268
[libx264 @ 0x7f9566801200] frame B:1054 Avg QP:23.93 size: 2612
[libx264 @ 0x7f9566801200] consecutive B-frames: 1.5% 0.7% 0.2% 97.6%
[libx264 @ 0x7f9566801200] mb I I16..4: 13.1% 68.3% 18.6%
[libx264 @ 0x7f9566801200] mb P I16..4: 1.6% 5.9% 0.6% P16..4: 30.9% 7.0% 3.9% 0.0% 0.0% skip:50.1%
[libx264 @ 0x7f9566801200] mb B I16..4: 0.1% 0.3% 0.0% B16..8: 27.7% 1.8% 0.3% direct: 0.7% skip:69.0% L0:42.9% L1:54.3% BI: 2.9%
[libx264 @ 0x7f9566801200] 8x8 transform intra:70.6% inter:84.0%
[libx264 @ 0x7f9566801200] coded y,uvDC,uvAC intra: 41.5% 51.8% 27.2% inter: 5.2% 6.5% 0.7%
[libx264 @ 0x7f9566801200] i16 v,h,dc,p: 32% 21% 8% 39%
[libx264 @ 0x7f9566801200] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 25% 16% 27% 5% 5% 6% 5% 5% 5%
[libx264 @ 0x7f9566801200] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 30% 23% 14% 5% 7% 6% 7% 5% 4%
[libx264 @ 0x7f9566801200] i8c dc,h,v,p: 59% 16% 18% 7%
[libx264 @ 0x7f9566801200] Weighted P-Frames: Y:0.5% UV:0.3%
[libx264 @ 0x7f9566801200] ref P L0: 63.9% 8.5% 18.4% 9.2% 0.1%
[libx264 @ 0x7f9566801200] ref B L0: 89.3% 8.5% 2.3%
[libx264 @ 0x7f9566801200] ref B L1: 95.5% 4.5%
[libx264 @ 0x7f9566801200] kb/s:890.50
我还尝试使用简单的曲线滤镜 ( ) 来校正阴影中的亮度-vf curves=m='0/0 0.1/0.18 0.25/0.33 1/1'：效果还不错，但色调很难/几乎不可能像这样校正。所以我想正确地做到这一点......
任何帮助表示感谢，谢谢
编辑
我尝试了 @Rotem 在评论中的建议，将调整大小功能嵌入 zscale 滤镜中。亮度效果好多了，但颜色仍然色调不对（太红了）。
下面是我在屏幕上看到的一些截图：
原始文件；这最初是一张黑暗的镜头，但它看起来比实际的还要暗：
我最初的更正；与我在问题中第一次写的相反，它稍有变化，但非常微妙：
使用@Rotem 建议的修正；亮度好多了（实际上已经接近应该的亮度了），但色调仍然太红了：
有趣的是，这是 VLC 内置捕获的结果，它更像是帧提取和屏幕截图。它显示了场景应有的样子（它仍然很暗，但至少头发中有一些细节，色调非常自然）。我猜 VLC 在输出 png 文件（似乎具有 sRGB 配置文件）时应用了适当的颜色配置文件转换：
