Bug 1748540 Comment 8 Edit History

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In this [case](), search `720p.png.bt709.bt709.pc.yuv420p.vp9.webm`, then you can see video could show difference between 235&255 and 0&16, but `720p.png.bt709.bt709.pc.yuv420p.av1.webm` couldn't. And I know these two are both videos, but if the way of comparing two videos in a reftest is capturing them in a canvas, then is it possible that the result showing for `av1` is not actually what AV1 video looks like? 

Although I don't know why the image for vp9 could show the correct color, AV1 couldn't. I suspect that there might be some bug in the reftest? The reftest result above were tested for my ffmpeg patches, which won't affect AV1 (dav1decoder), so I don't think my patch would affect AV1's result.

> most part it should be contained in sRGB.
So you mean sRGB should be able to display both (235,235,235) and (255,255,255) in different color? If so, then back to my intiail question, why the image I captured in canvas couldn't show such color? It couldn't display the difference between 235 and 255, which pixels all look the same.

Thank you!
In this [case](), search `720p.png.bt709.bt709.pc.yuv420p.vp9.webm`, then you can see video could show difference between 235&255 and 0&16, but `720p.png.bt709.bt709.pc.yuv420p.av1.webm` couldn't. And I know these two are both videos, but if the way of comparing two videos in a reftest is capturing them in a canvas, then is it possible that the result showing for `av1` is not actually what AV1 video looks like? 

Although I don't know why the image for vp9 could show the correct color, AV1 couldn't. I suspect that there might be some bug in the reftest? The reftest result above were tested for my ffmpeg patches, which won't affect AV1 (dav1decoder), so I don't think my patch would affect AV1's result.

> most part it should be contained in sRGB.

So you mean sRGB should be able to display both (235,235,235) and (255,255,255) in different color? If so, then back to my intiail question, why the image I captured in canvas couldn't show such color? It couldn't display the difference between 235 and 255, which pixels all look the same.

Thank you!

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