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

[Loren Merritt]

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.

You could still do one block, and just omit the trailing piece of a 
stride.

--Loren Merritt