[XviD-devel] zig-zag

skal skal at planet-d.net
Wed Mar 12 17:12:08 CET 2003


	Gruel,

On Wed, 2003-03-12 at 16:44, Christoph Lampert wrote:
> On Wed, 12 Mar 2003, Christoph Lampert wrote:
> > But maybe the peaks are the reason why HQAC-PRED works. Btw. that just
> > checks for 1 directions (which is write to acpred_directions[block] in
> > predict_acdc()). Shouldn't somehow both be checked? 
> 
> Sorry, no. If I see it right, then AC prediction can just be switched on
> or off, the direction is determined by DC prediction and that the encoder
> can't decide on! It's calculated from neighbouring blocks DCT gradient. 
> 
> This sound horrible... is that right?

	As far as I recall, yes. Only in interlace mode does the
	Alt_Vertical_Scan flag, if enabled, bypasses the gradient
	decision by forcing vertical scan...

		Skal




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