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JPEG Processing - 4:2:2 v 4:2:0?

Question asked by Laz on Dec 27, 2010
Latest reply on Jul 5, 2011 by SteveT

My JPEG saga continue...

 

I am using a BF561 single core to compress a 640x480 YUV 4:2:2 image into JPEG format, employing the ADI JPEG Library tools.  I am getting very poor performance compared with the reference results from the Spec Sheet.  The Spec Sheet says that a colorful 512x512 YUV4:2:0 image with a quality factor of 20 will compress to 27KB in 10*10^6  cycles.  I have a boring 640x480 YUV4:2:2 image that produces a 45K image in 60*10^6 cycles (120mS @510MHz CLK).  The input and output buffers are in separate banks of SDRAM.  All other factors are defaults for Sequential JPEG encoding.

 

Any idea why it's so slow?  Even with twice the pixel data, it shouldn't be 5-6 times slower.

 

TIA

Dan

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