[Webkit-unassigned] [Bug 181445] WebGL video texture black in Safari 11.0.2 and wrong colored in Safari Preview 11.1

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Wed Jan 10 12:30:47 PST 2018


https://bugs.webkit.org/show_bug.cgi?id=181445

--- Comment #18 from Klaus Reinfeld <mail at krpano.com> ---
(In reply to Jer Noble from comment #17)
> However, if you add the ffmpeg flags to make the colorspace, primaries,
> transfer function, and range explicit (rather than implicit from the pixel
> format), the color comes out correctly in a sample WebGL test:
> 
> ffmpeg -r 30 -f image2 -s 1920x1080 -i SMPTE_Color_Bars_16x9/%d.png -vcodec
> libx264 -crf 25 -pix_fmt yuvj420p -color_primaries bt709  -color_trc bt709
> -colorspace bt709 -color_range pc test-colorspace-bt709-420f.mp4
> 

I have added an additional video ('yuvj420p-bt709') encoded with these settings to the test case:

https://krpano.com/video/pixelformattest/

and yes, with these settings the colors are correct.



> You can verify that these metadata flags are added to the output file with
> mediainfo:
> 
> > mediainfo test-colorspace-bt709-420f.mp4         
> ...snip...
> Color range                              : Full
> Color primaries                          : BT.709
> Transfer characteristics                 : BT.709
> Matrix coefficients                      : BT.709

Sorry, I don't know about 'mediainfo' but here the video files from the above example for downloading (~30mb per file):

https://krpano.com/video/pixelformattest/yuv420p.mp4
https://krpano.com/video/pixelformattest/yuv422p.mp4
https://krpano.com/video/pixelformattest/yuv444p.mp4
https://krpano.com/video/pixelformattest/yuvj420p.mp4
https://krpano.com/video/pixelformattest/yuvj420p-bt709.mp4
https://krpano.com/video/pixelformattest/yuvj422p.mp4
https://krpano.com/video/pixelformattest/yuvj424p.mp4



> So you probably just need to make your colorspaces explicit, so that UAs can
> apply the correct transforms when generating RGB output.

Okay, but that can't be the solution, or?

All other videoplayers (also the Quicktime player) are showing the color correct also without that settings.

So maybe a kind of 'default behavior' when these settings are missing is wrong in the Safari WebGL video texture color conversion?

---

Btw - about the BLACK texture problem in Safari 11.0.2 with that example:
https://krpano.com/krpanocloud/video/airpano/

Could that be related to this bug?:
https://trac.webkit.org/browser/webkit/trunk/Source/WebCore/platform/graphics/cv/VideoTextureCopierCV.cpp?rev=222198

A broken OpenGL state could explain the behavior why some codes/examples are working and some others not...

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