[FFmpeg-devel] [PATCH] memcpy-less expand

Michael Tison blackspike
Fri Sep 18 10:20:26 CEST 2009

On Thu, Sep 17, 2009 at 4:31 PM, Stefano Sabatini
<stefano.sabatini-lala at poste.it> wrote:
> Hi, note that a pad / expand filter has been already discussed.
> Please check this thread:
> http://thread.gmane.org/gmane.comp.video.ffmpeg.devel/89945/focus=93912

Sorry! I was checking the mailing list for expand filters for some reason.

On Thu, Sep 17, 2009 at 11:41 PM, Vitor Sessak <vitor1001 at gmail.com> wrote:
> Thanks for the patch, but I think there is a little misunderstanding about
> memcpy-less expand. When we refer to it, we are actually talking about a
> O(1) expand. In your code, there is this loop:
[. . .]
> Where one could replace the inner loop by a memcpy and two memset if they
> inlined the in_region() function. What we would want is a expand filter that
> would just change the pic->data[] pointers and not touch the data inside it,
> but it would need the data[] buffer to be already alloc'ed with the right
> size someway, that's the tricky part.

Ah, thanks for the explanation, that makes sense.


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