Mailinglist Archive: radeonhd (288 mails)

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http://bugs.freedesktop.org/show_bug.cgi?id=22901


Yang Zhao <yang@xxxxxxxxxx> changed:

           What    |Removed                     |Added
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         AssignedTo|lverhaegen@xxxxxxx          |yang@xxxxxxxxxx




--- Comment #1 from Yang Zhao <yang@xxxxxxxxxx>  2009-07-22 19:47:53 PST ---
(In reply to comment #0)
> Created an attachment (id=27928)
 --> (http://bugs.freedesktop.org/attachment.cgi?id=27928) [details]
> patch to fix YUV scaling and use Rec709 coefficients
>
> radeonhd uses certain constants in the conversion from YUV to RGB in the Xv
> code.
> However, there's a minor scaling bug where 256 is used instead of 255 as the
> maximum value of an 8-bit unsigned.

Good catch. Those off-by-ones always gets ya. ;)

I'll push this change once I get my commit access (soon), if no one else has
done it already.


> In addition, the entries of the matrix A used to perform the following
> computation
> [Y; Cb; Cr] = A * [R; G; B]
> should probably be those given in Rec 709 (see
> http://en.wikipedia.org/wiki/Rec._709).

We're using the constants from Rec. 601. There was talk of detecting the media
size so that a switch to Rec. 709 can be made, but it hasn't been implemented.

Personally, I'm open to switching to 709 instead, as quality matters more for
HD than SD.


> Without this patch, the white level (contrast control) test pattern from AVS 
> HD
> 709 (explained at http://www.avsforum.com/avs-vb/showthread.php?t=948496 , MP4
> version available at http://www.sendspace.com/file/kaotq5)

Thanks for the test file link.


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