Hi,
It seems to be a bug (maybe by design) when trying to control how the
video/color ranges are treated in the "scale" filter.
Basically what I need to specify is that the range should NOT be converted
when input range == output range, for example:
in_range=pc:out_range=pc or
in_range=tv:out_range=tv
In my head there should be NO range conversion in either commands.
However, this does not seem to be the case. If you look at the test
commands below and their output you will see that a range conversion has
taken place even though input range and output range are set to be the
exact same. The only parameters I change are the scale width and height.
I'm using a late august 2021 build.
Command:
ffmpeg -f lavfi -i smptebars=duration=1:size=720x576:rate=1 -vf
"signalstats,metadata=print:key=lavfi.signalstats.YMIN,metadata=print:key=lavfi.signalstats.YMAX,scale=w=1920:h=1080:in_color_matrix=bt709:out_color_matrix=bt709:in_range=pc:out_range=pc,signalstats,metadata=print:key=lavfi.signalstats.YMIN,metadata=print:key=lavfi.signalstats.YMAX"
-f null -
Raw FFmpeg output:
ffmpeg version N-103405-g1930a85e83 Copyright (c) 2000-2021 the FFmpeg
developers
built with gcc 10.3.0 (Rev2, Built by MSYS2 project)
configuration: --disable-static --enable-shared --pkg-config=pkgconf
--cc='ccache gcc' --cxx='ccache g++' --disable-autodetect --enable-amf
--enable-bzlib --enable-cuda --enable-cuvid --enable-d3d11va --enable-dxva2
--enable-iconv --enable-lzma --enable-nvenc --enable-zlib --enable-sdl2
--enable-ffnvcodec --enable-nvdec --enable-cuda-llvm --enable-libmp3lame
--enable-libopus --enable-libvorbis --enable-libx264 --enable-libx265
--enable-libdav1d --enable-libaom --disable-debug --enable-fontconfig
--enable-libass --enable-libbluray --enable-libfreetype --enable-libmfx
--enable-libmysofa --enable-libopencore-amrnb --enable-libopencore-amrwb
--enable-libopenjpeg --enable-libsnappy --enable-libsoxr --enable-libspeex
--enable-libtheora --enable-libtwolame --enable-libvidstab
--enable-libvo-amrwbenc --enable-libwebp --enable-libxml2 --enable-libzimg
--enable-libshine --enable-gpl --enable-avisynth --enable-libxvid
--enable-libopenmpt --enable-version3 --enable-libsrt --enable-libgsm
--enable-libvmaf --enable-libsvtav1 --enable-mbedtls
--extra-cflags=-DLIBTWOLAME_STATIC --extra-libs=-lstdc++
--extra-cflags=-DLIBXML_STATIC --extra-libs=-liconv --disable-w32threads
--shlibdir=/local64/bin-video
libavutil 57. 4.101 / 57. 4.101
libavcodec 59. 6.100 / 59. 6.100
libavformat 59. 4.102 / 59. 4.102
libavdevice 59. 0.101 / 59. 0.101
libavfilter 8. 4.100 / 8. 4.100
libswscale 6. 0.100 / 6. 0.100
libswresample 4. 0.100 / 4. 0.100
libpostproc 56. 0.100 / 56. 0.100
Input #0, lavfi, from 'smptebars=duration=1:size=720x576:rate=1':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: rawvideo (I420 / 0x30323449), yuv420p, 720x576 [SAR
1:1 DAR 5:4], 1 tbr, 1 tbn
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> wrapped_avframe (native))
Press [q] to stop, [?] for help
[Parsed_metadata_1 @ 00000298dcb6c7c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_1 @ 00000298dcb6c7c0] lavfi.signalstats.YMIN=7
[Parsed_metadata_2 @ 00000298dcb6bcc0] frame:0 pts:0 pts_time:0
[Parsed_metadata_2 @ 00000298dcb6bcc0] lavfi.signalstats.YMAX=235
[swscaler @ 00000298dcb7fec0] Warning: data is not aligned! This can lead
to a speed loss
[Parsed_metadata_5 @ 00000298dcb6b0c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_5 @ 00000298dcb6b0c0] lavfi.signalstats.YMIN=0
[Parsed_metadata_6 @ 00000298dcb6b4c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_6 @ 00000298dcb6b4c0] lavfi.signalstats.YMAX=255
Output #0, null, to 'pipe:':
Metadata:
encoder : Lavf59.4.102
Stream #0:0: Video: wrapped_avframe, yuv420p(pc, progressive), 1920x1080
[SAR 45:64 DAR 5:4], q=2-31, 200 kb/s, 1 fps, 1 tbn
Metadata:
encoder : Lavc59.6.100 wrapped_avframe
frame= 1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:01.00 bitrate=N/A
speed=20.1x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: unknown
If we can trust the signalstats filter, YMIN has gone from 7 to 0, YMAX has
gone from 235 to 255
Furthermore, it's not consistent:
Command:
ffmpeg -f lavfi -i smptebars=duration=1:size=720x576:rate=1 -vf
"signalstats,metadata=print:key=lavfi.signalstats.YMIN,metadata=print:key=lavfi.signalstats.YMAX,scale=w=1280:h=720:in_color_matrix=bt709:out_color_matrix=bt709:in_range=pc:out_range=pc,signalstats,metadata=print:key=lavfi.signalstats.YMIN,metadata=print:key=lavfi.signalstats.YMAX"
-f null -
Washed FFmpeg output:
[Parsed_metadata_1 @ 000001ab9f8dc9c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_1 @ 000001ab9f8dc9c0] lavfi.signalstats.YMIN=7
[Parsed_metadata_2 @ 000001ab9f8db3c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_2 @ 000001ab9f8db3c0] lavfi.signalstats.YMAX=235
[swscaler @ 000001ab9f8efec0] Warning: data is not aligned! This can lead
to a speed loss
[Parsed_metadata_5 @ 000001ab9f8dc4c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_5 @ 000001ab9f8dc4c0] lavfi.signalstats.YMIN=5
[Parsed_metadata_6 @ 000001ab9f8db5c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_6 @ 000001ab9f8db5c0] lavfi.signalstats.YMAX=255
In this case YMIN has gone from 7 to 5, YMAX has gone from 235 to 255
Here are a few more:
ffmpeg -f lavfi -i smptebars=duration=1:size=720x576:rate=1 -vf
"signalstats,metadata=print:key=lavfi.signalstats.YMIN,metadata=print:key=lavfi.signalstats.YMAX,scale=w=720:h=720:in_color_matrix=bt709:out_color_matrix=bt709:in_range=pc:out_range=pc,signalstats,metadata=print:key=lavfi.signalstats.YMIN,metadata=print:key=lavfi.signalstats.YMAX"
-f null -
[Parsed_metadata_1 @ 000001fb530bb9c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_1 @ 000001fb530bb9c0] lavfi.signalstats.YMIN=7
[Parsed_metadata_2 @ 000001fb530bb0c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_2 @ 000001fb530bb0c0] lavfi.signalstats.YMAX=235
[swscaler @ 000001fb530cfe80] Warning: data is not aligned! This can lead
to a speed loss
[Parsed_metadata_5 @ 000001fb530bb2c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_5 @ 000001fb530bb2c0] lavfi.signalstats.YMIN=7
[Parsed_metadata_6 @ 000001fb530bbbc0] frame:0 pts:0 pts_time:0
[Parsed_metadata_6 @ 000001fb530bbbc0] lavfi.signalstats.YMAX=243
ffmpeg -f lavfi -i smptebars=duration=1:size=720x576:rate=1 -vf
"signalstats,metadata=print:key=lavfi.signalstats.YMIN,metadata=print:key=lavfi.signalstats.YMAX,scale=w=720:h=719:in_color_matrix=bt709:out_color_matrix=bt709:in_range=pc:out_range=pc,signalstats,metadata=print:key=lavfi.signalstats.YMIN,metadata=print:key=lavfi.signalstats.YMAX"
-f null -
[Parsed_metadata_1 @ 00000229dd9bc2c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_1 @ 00000229dd9bc2c0] lavfi.signalstats.YMIN=7
[Parsed_metadata_2 @ 00000229dd9bc0c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_2 @ 00000229dd9bc0c0] lavfi.signalstats.YMAX=235
[swscaler @ 00000229dd9cfe80] Warning: data is not aligned! This can lead
to a speed loss
[Parsed_metadata_5 @ 00000229dd9bb6c0] frame:0 pts:0 pts_time:0
[Parsed_metadata_5 @ 00000229dd9bb6c0] lavfi.signalstats.YMIN=4
[Parsed_metadata_6 @ 00000229dd9bafc0] frame:0 pts:0 pts_time:0
[Parsed_metadata_6 @ 00000229dd9bafc0] lavfi.signalstats.YMAX=251
So again, you can see how the behavior is difficult to control and it seems
to be related to the actual scaling of the image. So I'm hoping someone can
shed light on this behavior.
Thanks
-steinar
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