[jitter] cc.uyvy2rgba.jxs and optimization

Im 90% sure. In fact, FOURCCs YUV to ARGB conversion guide states:

Avery Lee's JFIF Clarification
"The equations you have from "Video Demystified" are the ones to use  
most of the time on PCs, such as for MPEG-1 decoding and handing most  
(all?) of the formats on the YUV FOURCC page. However, there is one  
notable exception: JPEG. The JFIF file format that is commonly used  
with JPEG defines a YCbCr color space that is slightly different than  
usual, in that all components have the full [0,255] excursion rather  
than [16,235] and [16,240]. The equations given by "Julien" are for  
this variant and are very close to the ones in JFIF:

R = Y + 1.402 (Cr-128)

G = Y - 0.34414 (Cb-128) - 0.71414 (Cr-128)

B = Y + 1.772 (Cb-128)

It should be noted that some Motion JPEG codecs don't take this  
consideration into account and improperly exchange YCbCr values  
between the YUY2 and UYVY formats and their internal JPEG planes  
without performing the necessary scaling. This results in contrast  
shifts when using YUV formats."

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Im not sure if id take that as gospel, (or, um, you know what I mean),  
I did a quick google search and while I did not see any giant blinking  
times square neon sign stating mjpeg/photojpeg video codecs are YUV, I  
saw lots of inferences to that point.

I'll check your patch out in a few. Thanks.

these sorts of discussions are great.

On Jan 3, 2008, at 8:25 AM, John Dekron wrote:

> Photo Jpeg is a YUV Codec? and I was was convinced it stores RGB  
> Data. I will have to do my homework on that.