[XviD-devel] dark blocks in b-frames

Radek Czyz radoslaw at syskin.cjb.net
Sat Feb 15 23:59:03 CET 2003


> Ok, so quantization rounds towards zero, and then dequantization
> assumes that the rounding was as bad as possible? That's weird. I
> don't get it. Why 13, when the average error is 6? MPEG4's weird.

Ok wait.. 13 is not quant-1, it's 2*quant-1. So maybe it's really 6?

BTW I do get it now - the idea was to make bigger values still quntize
to 0. So the smallest possible DC change is 4*quant-1. OK, whatever.

Can you tell me the way DC is quantized in mpeg quant type? I'll try
to write a code which prevents the black blocks.

Radek



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