[FFmpeg-devel] [PATCH] swscale: Only copy dstW/chrDstW of the last line in the plane in planar copy

[Michael Niedermayer]

On Fri, Jul 16, 2010 at 10:25:12AM +0300, Martin Storsj? wrote:
> On Fri, 16 Jul 2010, Martin Storsj? wrote:
> 
> > The attached patch makes planarCopyWrapper all lines but the last in one 
> > block, then copies only dstW/chrDstW of the last line.
> > 
> > If the destination planes are offset within their buffer, copying the 
> > whole plane in one memcpy may write outside of the destination buffer.
> > 
> > A concrete example: The source data is 144x144, stored in the upper left 
> > corner of a 176x144 buffer. If this is "scaled" into 144x144 into another 
> > 176x144 buffer, but centered into this buffer, the approach wich memcpying 
> > the whole plane writes outside of the destination buffer.
> 
> Updated patch - uses the already existing length variable instead of 
> recalculating it.

the caller could even expect that the non last lines width..stride is
preserved as well (example picture in picture filters.

what speed effect does it have to do this with all lines?
if its slower we could pass a flag to swscale.

that said your patch could be applied, it fixes a bug but i dont think
this will be the final solution


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
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