[FFmpeg-trac] #3345(swscale:open): Bias in planar YUV to YUV bit depth conversion
FFmpeg
trac at avcodec.org
Wed Sep 8 17:06:20 EEST 2021
#3345: Bias in planar YUV to YUV bit depth conversion
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Reporter: abc123 | Owner: (none)
Type: defect | Status: open
Priority: normal | Component: swscale
Version: git-master | Resolution:
Keywords: bounty | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by pdr0):
Replying to [comment:13 Balling]:
> Are results worse with dither? I suppose the problem here is that
strange double color dither even with dither none, you reproduced that on
that AV1 file, rememember? Why I somehow did not.
>
> >fluctuates a bit, almost as if output is dithered
>
> https://trac.ffmpeg.org/ticket/9167#comment:10
Yes, results are worse with dither. I'll revisit the other ticket later
For this ticket , I attached a 1280x720 yuv444p10le .yuv frame, single
color YUV 523,503,559 so it's easier to reproduce the issue and ease of
testing
ffmpeg -pix_fmt yuv444p10le -s 1280x720 -i
1280x720_yuv444p10le_523_503_559.yuv -vf zscale=dither=none,format=yuv444p
-f rawvideo test02_zscale_nodither.yuv
YUV 130,125,139
ffmpeg -pix_fmt yuv444p10le -s 1280x720 -i
1280x720_yuv444p10le_523_503_559.yuv -vf
scale=sws_dither=none,format=yuv444p -f rawvideo
test02b_swscale_nodither.yuv
YUV 131,126,140
I tried some sws flags such as accurate_rnd, but no change
--
Ticket URL: <https://trac.ffmpeg.org/ticket/3345#comment:14>
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