[FFmpeg-trac] #3795(swscale:new): SWSCALE: Quantization Errors in Y Studio Range
FFmpeg
trac at avcodec.org
Wed Jul 23 05:51:43 CEST 2014
#3795: SWSCALE: Quantization Errors in Y Studio Range
------------------------------------+--------------------------------------
Reporter: troy_s | Type: defect
Status: new | Priority: normal
Component: swscale | Version: git-master
Keywords: 709 Y luma | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
------------------------------------+--------------------------------------
Summary of the bug:
It appears FFMPEG has some +/- single unit quantization errors in the
YCbCr transform.
How to reproduce:
Generate a raw YCbCr image and diff against theoretically correct values.
{{{
./ffmpeg -i ~/Documents/FFMPEG\ Color\ Research/ARIB_STD-B28.png -pix_fmt
yuv444p -vcodec rawvideo -f rawvideo -vf
scale="in_range=full:in_color_matrix=bt709:out_range=full:out_color_matrix=bt709"
test.yuv
ffmpeg version N-64815-gb53bdae Copyright (c) 2000-2014 the FFmpeg
developers
built on Jul 19 2014 16:33:49 with gcc 4.8 (Ubuntu 4.8.2-19ubuntu1)
configuration: --enable-gpl --enable-libx264 --disable-asm
libavutil 52. 92.101 / 52. 92.101
libavcodec 55. 69.100 / 55. 69.100
libavformat 55. 48.101 / 55. 48.101
libavdevice 55. 13.102 / 55. 13.102
libavfilter 4. 11.102 / 4. 11.102
libswscale 2. 6.100 / 2. 6.100
libswresample 0. 19.100 / 0. 19.100
libpostproc 52. 3.100 / 52. 3.100
Input #0, image2, from '/home/aphorism/Documents/FFMPEG Color
Research/ARIB_STD-B28.png':
Duration: 00:00:00.04, start: 0.000000, bitrate: N/A
Stream #0:0: Video: png, rgb24, 1920x1080 [SAR 2835:2835 DAR 16:9], 25
tbr, 25 tbn, 25 tbc
Output #0, rawvideo, to 'test.yuv':
Metadata:
encoder : Lavf55.48.101
Stream #0:0: Video: rawvideo (444P / 0x50343434), yuv444p, 1920x1080
[SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
Metadata:
encoder : Lavc55.69.100 rawvideo
Stream mapping:
Stream #0:0 -> #0:0 (png (native) -> rawvideo (native))
Press [q] to stop, [?] for help
frame= 1 fps=0.0 q=0.0 Lsize= 6075kB time=00:00:00.04
bitrate=1244160.0kbits/s
video:6075kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 0.000000%
}}}
Diff'd versions of the theoretically ideal values versus FFMPEG's output.
Lowest red stripe is due to theoretical version preserving the -2% patch,
and not relevant.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/3795>
FFmpeg <https://ffmpeg.org>
FFmpeg issue tracker
More information about the FFmpeg-trac
mailing list