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Date:      Thu, 26 Feb 1998 20:32:10 -0800
From:      Amancio Hasty <hasty@rah.star-gate.com>
To:        brian@worldcontrol.com
Cc:        hasty@star-gate.com, freebsd-multimedia@FreeBSD.ORG
Subject:   Re: data format for meteor/bt848 METEOR_GEO_YUV_12 mode? 
Message-ID:  <199802270432.UAA18678@rah.star-gate.com>
In-Reply-To: Your message of "Thu, 26 Feb 1998 20:12:00 PST." <19980226201200.A3016@top.worldcontrol.com> 

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For the meteor, you can look it up at :
ftp://rah.star-gate.com/pub/saa7196.pdf

For the bt848 driver :

Y = (x * y)
U = (x/2 * y/2 )
v = (x/2 * y/2 )

The actual routine which does the dma transfer is yuv12_prog:

...
        for (i = 0; i < (rows/interlace )/2 ; i++) {
                *dma_prog++ = inst;
                *dma_prog++ = cols/2 | (cols/2 << 16);
                *dma_prog++ = target_buffer;
                *dma_prog++ = t1 + (cols*rows) + i*cols/2 * interlace;
                *dma_prog++ = t1 + (cols*rows) + (cols*rows/4) + i*cols/2 * 
inte
rlace;
                target_buffer += interlace*cols;
                *dma_prog++ = inst1;
                *dma_prog++ = cols/2 | (cols/2 << 16);
                *dma_prog++ = target_buffer;
                target_buffer += interlace*cols;

        }

....


	Have Fun,
	Amancio




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