[XviD-devel] zig-zag

skal skal at planet-d.net
Wed Mar 12 10:46:26 CET 2003


	Hi Gruel,


On Wed, 2003-03-12 at 10:33, Christoph Lampert wrote:
> On Wed, 12 Mar 2003, Christoph Lampert wrote:
> 
> > 
> > Hi,
> > 
> > is it possible to change zigzag order on block level? Or just on
> > per-frame-basis? Or is it automatically chosen based on interlace on/off?
> 
> Just if somebody knows immediately, otherwise I'll look it up.
> 

	For intra-mb, in I-frame, the AC-prediction direction is
	used to choose between horizontal/vertical scan. But in
	interlaced mode, if the Alternate-vertical-flag is on,
	it's always the vertical mode.
	for intra-mb in a P-frame, with the flag off, it's the
	"regular" order that is used.

	For inter-mb, "regular" or "vertical" scan is chosen
	according to the Alternate-vertical-flag...

	(hope I didn't missed something)

	bye,
		Skal





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