Am 12.04.2012 14:23, schrieb Ville Syrjälä: > On Wed, Apr 11, 2012 at 08:53:08PM +0200, Roland Scheidegger wrote: >> Am 05.04.2012 20:35, schrieb ville.syrjala@xxxxxxxxxxxxxxx: >>> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >>> >>> These functions return the chroma subsampling factors for the specified >>> pixel format. >> Hmm not really related but looking at it this reminds me these formats >> always look a bit underspecified wrt chroma subsample positions. Are >> these fixed, undefined, or what (even mpeg1 and mpeg2 differ there, and >> let's not even talk about the big mess that interlaced mpeg2 is)? > > My thinking is that the sample positions can be configured through > some other means. It doesn't affect the in memory layout at all so > tying it to the format isn't necessary. > > This also depends on the hardware. On some hardware you can configure > it quite freely, but on some you may be left with just the one option, > which is often not even documented. > > I sent another patch [1] some time ago which provides a helper function > for drivers dealing with good hardware. > > [1] http://lists.freedesktop.org/archives/dri-devel/2011-December/017585.html > I guess that makes sense. As long as those "other means" are available. Not like with xv where I think drivers just default to what is probably the most likely subsample positions, so assuming mpeg2/4 progressive or something (which gets mpeg1 slightly wrong), if they even bother to care about such subtleties :-). Roland _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
