#11646: Full range RGB to YUV conversion using swscale has a slight green tint.
---------------------------------+--------------------------------------
Reporter: Jorn | Type: defect
Status: new | Priority: normal
Component: swscale | Version: git-master
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
---------------------------------+--------------------------------------
Summary of the bug:
Converting full range RGB to YUV using swscale causes the output to have a
slight green tint.
How to reproduce:
{{{
% ffmpeg -loop 1 -t 10 -i gradient.png -sws_flags
spline+accurate_rnd+full_chroma_int+full_chroma_inp+bitexact -vf
"setparams=colorspace=bt709:range=pc,scale,format=yuv444p" -crf 0
output.mp4
ffmpeg version N-120037-g36c8eef42c-20250625 Copyright (c) 2000-2025 the
FFmpeg developers
built with gcc 15.1.0 (crosstool-NG 1.27.0.42_35c1e72)
configuration: --prefix=/ffbuild/prefix --pkg-config-flags=--static
--pkg-config=pkg-config --cross-prefix=x86_64-w64-mingw32- --arch=x86_64
--target-os=mingw32 --enable-gpl --enable-version3 --disable-debug
--disable-w32threads --enable-pthreads --enable-iconv --enable-zlib
--enable-libfribidi --enable-gmp --enable-libxml2 --enable-lzma --enable-
fontconfig --enable-libharfbuzz --enable-libfreetype --enable-libvorbis
--enable-opencl --disable-libpulse --enable-libvmaf --disable-libxcb
--disable-xlib --enable-amf --enable-libaom --enable-libaribb24 --enable-
avisynth --enable-chromaprint --enable-libdav1d --enable-libdavs2
--enable-libdvdread --enable-libdvdnav --disable-libfdk-aac --enable-
ffnvcodec --enable-cuda-llvm --enable-frei0r --enable-libgme --enable-
libkvazaar --enable-libaribcaption --enable-libass --enable-libbluray
--enable-libjxl --enable-libmp3lame --enable-libopus --enable-librist
--enable-libssh --enable-libtheora --enable-libvpx --enable-libwebp
--enable-libzmq --enable-lv2 --enable-libvpl --enable-openal --enable-
liboapv --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-
libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-librav1e
--enable-librubberband --enable-schannel --enable-sdl2 --enable-libsnappy
--enable-libsoxr --enable-libsrt --enable-libsvtav1 --enable-libtwolame
--enable-libuavs3d --disable-libdrm --enable-vaapi --enable-libvidstab
--enable-vulkan --enable-libshaderc --enable-libplacebo --enable-libvvenc
--enable-libx264 --enable-libx265 --enable-libxavs2 --enable-libxvid
--enable-libzimg --enable-libzvbi --extra-cflags=-DLIBTWOLAME_STATIC
--extra-cxxflags= --extra-libs=-lgomp --extra-ldflags=-pthread --extra-
ldexeflags= --cc=x86_64-w64-mingw32-gcc --cxx=x86_64-w64-mingw32-g++
--ar=x86_64-w64-mingw32-gcc-ar --ranlib=x86_64-w64-mingw32-gcc-ranlib
--nm=x86_64-w64-mingw32-gcc-nm --extra-version=20250625
libavutil 60. 3.100 / 60. 3.100
libavcodec 62. 4.100 / 62. 4.100
libavformat 62. 1.100 / 62. 1.100
libavdevice 62. 0.100 / 62. 0.100
libavfilter 11. 0.100 / 11. 0.100
libswscale 9. 0.100 / 9. 0.100
libswresample 6. 0.100 / 6. 0.100
Input #0, png_pipe, from 'gradient.png':
Duration: N/A, bitrate: N/A
Stream #0:0: Video: png, rgb24(pc, gbr/unknown/unknown), 1024x256 [SAR
1:1 DAR 4:1], 25 fps, 25 tbr, 25 tbn
Stream mapping:
Stream #0:0 -> #0:0 (png (native) -> h264 (libx264))
Press [q] to stop, [?] for help
[libx264 @ 0000016e93513600] using SAR=1/1
[libx264 @ 0000016e93513600] using cpu capabilities: MMX2 SSE2Fast SSSE3
SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 0000016e93513600] profile High 4:4:4 Predictive, level 3.0,
4:4:4, 8-bit
[libx264 @ 0000016e93513600] 64 - core 165 - H.264/MPEG-4 AVC codec -
Copyleft 2003-2025 - http://www.videolan.org/x264.html - options: cabac=1
ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=0 mixed_ref=1
me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11
fast_pskip=0 chroma_qp_offset=0 threads=8 lookahead_threads=1
sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0
constrained_intra=0 bframes=0 weightp=2 keyint=250 keyint_min=25
scenecut=40 intra_refresh=0 rc=cqp mbtree=0 qp=0
Output #0, mp4, to 'output.mp4':
Metadata:
encoder : Lavf62.1.100
Stream #0:0: Video: h264 (avc1 / 0x31637661), yuv444p(pc,
bt709/unknown/unknown, progressive), 1024x256 [SAR 1:1 DAR 4:1], q=2-31,
25 fps, 12800 tbn
Metadata:
encoder : Lavc62.4.100 libx264
Side data:
cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: N/A
[out#0/mp4 @ 0000016e934c7f80] video:38KiB audio:0KiB subtitle:0KiB other
streams:0KiB global headers:0KiB muxing overhead: 4.803696%
frame= 250 fps=0.0 q=-1.0 Lsize= 40KiB time=00:00:10.00 bitrate=
32.5kbits/s speed= 25x elapsed=0:00:00.40
[libx264 @ 0000016e93513600] frame I:1 Avg QP: 0.00 size: 31759
[libx264 @ 0000016e93513600] frame P:249 Avg QP: 0.00 size: 26
[libx264 @ 0000016e93513600] mb I I16..4: 79.7% 20.2% 0.1%
[libx264 @ 0000016e93513600] mb P I16..4: 0.0% 0.0% 0.0% P16..4:
0.0% 0.0% 0.0% 0.0% 0.0% skip:100.0%
[libx264 @ 0000016e93513600] 8x8 transform intra:20.2%
[libx264 @ 0000016e93513600] coded y,u,v intra: 99.0% 0.0% 0.0% inter:
0.0% 0.0% 0.0%
[libx264 @ 0000016e93513600] i16 v,h,dc,p: 26% 0% 10% 64%
[libx264 @ 0000016e93513600] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 36% 11% 37%
0% 1% 14% 0% 0% 0%
[libx264 @ 0000016e93513600] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 0% 0% 100%
0% 0% 0% 0% 0% 0%
[libx264 @ 0000016e93513600] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0000016e93513600] kb/s:30.58
}}}
This produces a slightly greenish gradient in the output when using
`ffmpeg version N-120037-g36c8eef42c-20250625`, using `ffmpeg version
n7.1.1-54-g6400860b9d-20250625` produces the correct gradient matching
`gradient.png`, as does using `zscale` instead of `scale`.
Seems to have broken between `ffmpeg version
N-117967-g4de67e8746-20241130` and `ffmpeg version
N-118197-gbb85423142-20241231`.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/11646>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker
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