[MPlayer-dev-eng] [PATCH] vf_scale: prevent copying data when nothing else to do

[Xidorn Quan]

It would be really nice if vf_scale can operate in-place, and do no
operation when needn't.
在 2012-8-18 下午5:40，"Reimar Döffinger" <Reimar.Doeffinger at gmx.de>写道：

> On Fri, Aug 17, 2012 at 10:38:14PM +0800, Xidorn Quan wrote:
> > It is a simple patch to prevent vf_scale from just copying data when
> > nothing need to be scaled actually.
>
> I don't think that's correct, if the frame buffer after the filter is
> different
> than the one before (e.g. because the incoming frame is a reference
> frame and thus has a PRESERVE flag while the next filter e.g. is expand
> drawing the vo) a copy is still needed.
> However that reminds me that it would be really nice if vf_scale and
> libswscale could operate in-place, it would reduce the memory bandwidth
> required by e.g. 10-bit to 16-bit conversion in about half and solve
> this problem as a side effect.
> Would be a good bit of effort to implement properly though.
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