Comments on: YCbCr Gamut Checking http://www.schleef.org/blog/2009/10/07/ycbcr-gamut-checking/ Just another WordPress weblog Mon, 12 Dec 2011 22:37:25 +0000 hourly 1 http://wordpress.org/?v=3.1 By: Gregory Maxwell http://www.schleef.org/blog/2009/10/07/ycbcr-gamut-checking/comment-page-1/#comment-3534 Gregory Maxwell Sat, 10 Oct 2009 17:12:25 +0000 http://www.schleef.org/blog/?p=36#comment-3534 It would be really handy to have 4:2:2 and 4:4:4 versions of these test clips because in some applications the different subsampling rates trigger entirely distinct code paths. It would also be interesting to have a set of 4:2:0 test cases that sweep offset and make sure the correct chroma row and column are being selected. I expect many applications would fail this when offset x or y is odd. It would be really handy to have 4:2:2 and 4:4:4 versions of these test clips because in some applications the different subsampling rates trigger entirely distinct code paths.

It would also be interesting to have a set of 4:2:0 test cases that sweep offset and make sure the correct chroma row and column are being selected. I expect many applications would fail this when offset x or y is odd.

]]> By: David Schleef: YCbCr Gamut Checking | Full-Linux.com http://www.schleef.org/blog/2009/10/07/ycbcr-gamut-checking/comment-page-1/#comment-3524 David Schleef: YCbCr Gamut Checking | Full-Linux.com Fri, 09 Oct 2009 06:06:22 +0000 http://www.schleef.org/blog/?p=36#comment-3524 [...] information related to your search David Schleef: YCbCr Gamut Checking is now available in this link…: News [...] [...] information related to your search David Schleef: YCbCr Gamut Checking is now available in this link…: News [...]

]]> By: admin http://www.schleef.org/blog/2009/10/07/ycbcr-gamut-checking/comment-page-1/#comment-3520 admin Thu, 08 Oct 2009 15:46:16 +0000 http://www.schleef.org/blog/?p=36#comment-3520 Philip: The bt709 video is for checking if applications/drivers are actually using the BT.709 matrix instead of BT.470 matrix. Of course, it would be displayed with a visible pattern if the entire display path was honoring the color information in the video, but most don't. Philip: The bt709 video is for checking if applications/drivers are actually using the BT.709 matrix instead of BT.470 matrix. Of course, it would be displayed with a visible pattern if the entire display path was honoring the color information in the video, but most don’t.

]]> By: Philip Jägenstedt http://www.schleef.org/blog/2009/10/07/ycbcr-gamut-checking/comment-page-1/#comment-3516 Philip Jägenstedt Thu, 08 Oct 2009 11:23:13 +0000 http://www.schleef.org/blog/?p=36#comment-3516 Ah, that would be http://en.wikipedia.org/wiki/Rec._709 which has a slightly different gamut. It seems Theora header can only represent BT.470, so it's no surprise the results are off. http://www.theora.org/doc/libtheora-1.1/codec_8h.html#a4ce7a695ce353b1582d29b6c1ddf31a0 Ah, that would be http://en.wikipedia.org/wiki/Rec._709 which has a slightly different gamut. It seems Theora header can only represent BT.470, so it’s no surprise the results are off. http://www.theora.org/doc/libtheora-1.1/codec_8h.html#a4ce7a695ce353b1582d29b6c1ddf31a0

]]> By: Philip Jägenstedt http://www.schleef.org/blog/2009/10/07/ycbcr-gamut-checking/comment-page-1/#comment-3515 Philip Jägenstedt Thu, 08 Oct 2009 11:01:51 +0000 http://www.schleef.org/blog/?p=36#comment-3515 Thanks for providing these samples, very useful. Could you say something about gamut-theora-bt709.ogv? As far as I can tell it's not in a different colorspace, but converting it to PNG (through ffmpegcolorspace) still shows a checkerboard pattern. Thanks for providing these samples, very useful. Could you say something about gamut-theora-bt709.ogv? As far as I can tell it’s not in a different colorspace, but converting it to PNG (through ffmpegcolorspace) still shows a checkerboard pattern.

]]> By: Anonymous http://www.schleef.org/blog/2009/10/07/ycbcr-gamut-checking/comment-page-1/#comment-3513 Anonymous Thu, 08 Oct 2009 09:10:25 +0000 http://www.schleef.org/blog/?p=36#comment-3513 The first video does indeed appear to have a checkerboard pattern in the white and red sections, in Firefox 3.5. Possibly the rounding error you mentioned, though it seems fairly pronounced. The first video does indeed appear to have a checkerboard pattern in the white and red sections, in Firefox 3.5. Possibly the rounding error you mentioned, though it seems fairly pronounced.

]]> By: admin http://www.schleef.org/blog/2009/10/07/ycbcr-gamut-checking/comment-page-1/#comment-3512 admin Thu, 08 Oct 2009 08:41:26 +0000 http://www.schleef.org/blog/?p=36#comment-3512 No, these are pretty typical Ogg/Theora videos. No, these are pretty typical Ogg/Theora videos.

]]> By: oliver http://www.schleef.org/blog/2009/10/07/ycbcr-gamut-checking/comment-page-1/#comment-3510 oliver Thu, 08 Oct 2009 08:23:29 +0000 http://www.schleef.org/blog/?p=36#comment-3510 Both videos only show completely green here :-( Do I need a recent Theora decoder for this? Both videos only show completely green here :-( Do I need a recent Theora decoder for this?

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