#9675: -vf overlay is not accurate with RGB input using embedded RGBA alpha
channel
----------------------------------+---------------------------------------
Reporter: pdr0 | Type: defect
Status: new | Priority: normal
Component: avfilter | Version: unspecified
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
----------------------------------+---------------------------------------
Summary of the bug:
-vf overlay is not accurate with RGB input using embedded RGBA alpha
channel
How to reproduce:
{{{
"D:\\_DOWNLOADS\\ffmpeg-master-latest-win64-gpl_20220302\\bin\\ffmpeg"
-report -i black.png -i white_withalpharamp.png -filter_complex
"[0:0][1:0]overlay" ffmpegoverlay_20220302.png -y
ffmpeg version N-105822-g4b72bca6ca-20220302 Copyright (c) 2000-2022 the
FFmpeg developers
built with gcc 11.2.0 (crosstool-NG 1.24.0.533_681aaef)
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-libxml2
--enable-zlib --enable-libfreetype --enable-libfribidi --enable-gmp
--enable-lzma --enable-fontconfig --enable-libvorbis --enable-opencl
--disable-libpulse --enable-libvmaf --disable-libxcb --disable-xlib
--enable-amf --enable-libaom --enable-avisynth --enable-libdav1d --enable-
libdavs2 --disable-libfdk-aac --enable-ffnvcodec --enable-cuda-llvm
--enable-frei0r --enable-libgme --enable-libass --enable-libbluray
--enable-libmp3lame --enable-libopus --enable-librist --enable-libtheora
--enable-libvpx --enable-libwebp --enable-lv2 --enable-libmfx --enable-
libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264
--enable-libopenjpeg --enable-libopenmpt --enable-librav1e --enable-
librubberband --enable-schannel --enable-sdl2 --en libavutil 57.
22.100 / 57. 22.100
libavcodec 59. 21.103 / 59. 21.103
libavformat 59. 17.102 / 59. 17.102
libavdevice 59. 5.100 / 59. 5.100
libavfilter 8. 27.100 / 8. 27.100
libswscale 6. 5.100 / 6. 5.100
libswresample 4. 4.100 / 4. 4.100
libpostproc 56. 4.100 / 56. 4.100
Splitting the commandline.
Reading option '-report' ... matched as option 'report' (generate a
report) with argument '1'.
Reading option '-i' ... matched as input url with argument 'black.png'.
Reading option '-i' ... matched as input url with argument
'white_withalpharamp.png'.
Reading option '-filter_complex' ... matched as option 'filter_complex'
(create a complex filtergraph) with argument '[0:0][1:0]overlay'.
Reading option 'ffmpegoverlay_20220302.png' ... matched as output url.
Reading option '-y' ... matched as option 'y' (overwrite output files)
with argument '1'.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option report (generate a report) with argument 1.
Applying option filter_complex (create a complex filtergraph) with
argument [0:0][1:0]overlay.
Applying option y (overwrite output files) with argument 1.
Successfully parsed a group of options.
Parsing a group of options: input url black.png.
Successfully parsed a group of options.
Opening an input file: black.png.
[NULL @ 000000c64e433b40] Opening 'black.png' for reading
[file @ 000000c64c90a040] Setting default whitelist 'file,crypto,data'
[png_pipe @ 000000c64e433b40] Format png_pipe probed with size=2048 and
score=99
[png_pipe @ 000000c64e433b40] Before avformat_find_stream_info() pos: 0
bytes read:285 seeks:0 nb_streams:1
[png_pipe @ 000000c64e433b40] After avformat_find_stream_info() pos: 285
bytes read:285 seeks:0 frames:1
Input #0, png_pipe, from 'black.png':
Duration: N/A, bitrate: N/A
Stream #0:0, 1, 1/25: Video: png, rgb24(pc), 256x256, 25 fps, 25 tbr, 25
tbn
Successfully opened the file.
Parsing a group of options: input url white_withalpharamp.png.
Successfully parsed a group of options.
Opening an input file: white_withalpharamp.png.
[NULL @ 000000c64c90b0c0] Opening 'white_withalpharamp.png' for reading
[file @ 000000c64c90c740] Setting default whitelist 'file,crypto,data'
[png_pipe @ 000000c64c90b0c0] Format png_pipe probed with size=2048 and
score=99
[png_pipe @ 000000c64c90b0c0] Before avformat_find_stream_info() pos: 0
bytes read:972 seeks:0 nb_streams:1
[png_pipe @ 000000c64c90b0c0] After avformat_find_stream_info() pos: 972
bytes read:972 seeks:0 frames:1
Input #1, png_pipe, from 'white_withalpharamp.png':
Duration: N/A, bitrate: N/A
Stream #1:0, 1, 1/25: Video: png, rgba(pc), 256x256, 25 fps, 25 tbr, 25
tbn
Successfully opened the file.
Parsing a group of options: output url ffmpegoverlay_20220302.png.
Successfully parsed a group of options.
Opening an output file: ffmpegoverlay_20220302.png.
Successfully opened the file.
detected 8 logical cores
Stream mapping:
Stream #0:0 (png) -> overlay
Stream #1:0 (png) -> overlay
overlay:default -> Stream #0:0 (png)
Press [q] to stop, [?] for help
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless
if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless
if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless
if it occurs once at the start per stream)
cur_dts is invalid st:0 (0) [init:0 i_done:0 finish:0] (this is harmless
if it occurs once at the start per stream)
[graph 0 input from stream 0:0 @ 000000c64e46c600] Setting 'video_size' to
value '256x256'
[graph 0 input from stream 0:0 @ 000000c64e46c600] Setting 'pix_fmt' to
value '2'
[graph 0 input from stream 0:0 @ 000000c64e46c600] Setting 'time_base' to
value '1/25'
[graph 0 input from stream 0:0 @ 000000c64e46c600] Setting 'pixel_aspect'
to value '0/1'
[graph 0 input from stream 0:0 @ 000000c64e46c600] Setting 'frame_rate' to
value '25/1'
[graph 0 input from stream 0:0 @ 000000c64e46c600] w:256 h:256
pixfmt:rgb24 tb:1/25 fr:25/1 sar:0/1
[graph 0 input from stream 1:0 @ 000000c64e46ca00] Setting 'video_size' to
value '256x256'
[graph 0 input from stream 1:0 @ 000000c64e46ca00] Setting 'pix_fmt' to
value '26'
[graph 0 input from stream 1:0 @ 000000c64e46ca00] Setting 'time_base' to
value '1/25'
[graph 0 input from stream 1:0 @ 000000c64e46ca00] Setting 'pixel_aspect'
to value '0/1'
[graph 0 input from stream 1:0 @ 000000c64e46ca00] Setting 'frame_rate' to
value '25/1'
[graph 0 input from stream 1:0 @ 000000c64e46ca00] w:256 h:256 pixfmt:rgba
tb:1/25 fr:25/1 sar:0/1
[format @ 000000c64e46c700] Setting 'pix_fmts' to value
'rgb24|rgba|rgb48be|rgba64be|pal8|gray|ya8|gray16be|ya16be|monob'
[auto_scale_0 @ 000000c64e46d700] w:iw h:ih flags:'' interl:0
[Parsed_overlay_0 @ 000000c64e46d900] auto-inserting filter 'auto_scale_0'
between the filter 'graph 0 input from stream 0:0' and the filter
'Parsed_overlay_0'
[auto_scale_1 @ 000000c64e46c800] w:iw h:ih flags:'' interl:0
[Parsed_overlay_0 @ 000000c64e46d900] auto-inserting filter 'auto_scale_1'
between the filter 'graph 0 input from stream 1:0' and the filter
'Parsed_overlay_0'
[auto_scale_2 @ 000000c64e46c900] w:iw h:ih flags:'' interl:0
[format @ 000000c64e46c700] auto-inserting filter 'auto_scale_2' between
the filter 'Parsed_overlay_0' and the filter 'format'
[AVFilterGraph @ 000000c64e475380] query_formats: 5 queried, 4 merged, 3
already done, 0 delayed
[auto_scale_2 @ 000000c64e46c900] picking rgba out of 10 ref:yuva420p
alpha:1
[auto_scale_0 @ 000000c64e46d700] w:256 h:256 fmt:rgb24 sar:0/1 -> w:256
h:256 fmt:yuva420p sar:0/1 flags:0x0
[auto_scale_1 @ 000000c64e46c800] w:256 h:256 fmt:rgba sar:0/1 -> w:256
h:256 fmt:yuva420p sar:0/1 flags:0x0
[Parsed_overlay_0 @ 000000c64e46d900] main w:256 h:256 fmt:yuva420p
overlay w:256 h:256 fmt:yuva420p
[Parsed_overlay_0 @ 000000c64e46d900] [framesync @ 000000c64e4767e8]
Selected 1/25 time base
[Parsed_overlay_0 @ 000000c64e46d900] [framesync @ 000000c64e4767e8] Sync
level 2
[auto_scale_2 @ 000000c64e46c900] w:256 h:256 fmt:yuva420p sar:0/1 ->
w:256 h:256 fmt:rgba sar:0/1 flags:0x0
[Parsed_overlay_0 @ 000000c64e46d900] n:1.000000 t:0.000000 pos:0.000000
x:0.000000 xi:0 y:0.000000 yi:0
Output #0, image2, to 'ffmpegoverlay_20220302.png':
Metadata:
encoder : Lavf59.17.102
Stream #0:0, 0, 1/25: Video: png, rgba(pc, gbr/unknown/unknown,
progressive), 256x256, q=2-31, 200 kb/s, 25 fps, 25 tbn
Metadata:
encoder : Lavc59.21.103 png
Clipping frame in rate conversion by 0.000008
frame= 1 fps=0.0 q=0.0 size=N/A time=00:00:00.00 bitrate=N/A speed=
0x
cur_dts is invalid st:0 (0) [init:1 i_done:0 finish:0] (this is harmless
if it occurs once at the start per stream)
[Parsed_overlay_0 @ 000000c64e46d900] [framesync @ 000000c64e4767e8] Sync
level 1
cur_dts is invalid st:0 (0) [init:1 i_done:0 finish:0] (this is harmless
if it occurs once at the start per stream)
[Parsed_overlay_0 @ 000000c64e46d900] [framesync @ 000000c64e4767e8] Sync
level 0
cur_dts is invalid st:0 (0) [init:1 i_done:0 finish:0] (this is harmless
if it occurs once at the start per stream)
[out_0_0 @ 000000c64e46c100] EOF on sink link out_0_0:default.
No more output streams to write to, finishing.
[image2 @ 000000c64e434740] Opening 'ffmpegoverlay_20220302.png' for
writing
[file @ 000000c64e450440] Setting default whitelist 'file,crypto,data'
[AVIOContext @ 000000c652d47ac0] Statistics: 2411 bytes written, 0 seeks,
1 writeouts
frame= 1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A
speed=0.251x
video:2kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: unknown
Input file #0 (black.png):
Input stream #0:0 (video): 1 packets read (285 bytes); 1 frames decoded;
Total: 1 packets (285 bytes) demuxed
Input file #1 (white_withalpharamp.png):
Input stream #1:0 (video): 1 packets read (972 bytes); 1 frames decoded;
Total: 1 packets (972 bytes) demuxed
Output file #0 (ffmpegoverlay_20220302.png):
Output stream #0:0 (video): 1 frames encoded; 1 packets muxed (2411
bytes);
Total: 1 packets (2411 bytes) muxed
2 frames successfully decoded, 0 decoding errors
[AVIOContext @ 000000c64e43c040] Statistics: 285 bytes read, 0 seeks
[AVIOContext @ 000000c64c90c980] Statistics: 972 bytes read, 0 seeks
}}}
black.png is RGB 0,0,0
white_withalpharamp.png is RGB 255,255,255 with a perfect 0-255 ramp for
the alpha channel, 256x256
The expected output is a perfect gradient 0-255, with each xpos having the
same R=G=B value. "greyscaleramp.png" is the expected output, and achieved
with other programs
The ffmpeg observed output has banding , some values are dropped, some are
repeated (but at least 0 and 255 are preserved for a binarized mask). This
has implications for compositing, greenscreen, non binarized masks
This test used RGB inputs, but the log says auto scaling to "fmt:yuva420p"
. My guess is there is some swscale issue - maybe RGB is being converted
to YUV and back with limited range at 8bit causing the quantization errors
, instead of operating as an RGB overlay. Or perhaps the intermediate YUV
operation could be performed at a higher bit depth to avoid those issues
--
Ticket URL: <https://trac.ffmpeg.org/ticket/9675>
FFmpeg <https://ffmpeg.org>
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