[Libav-user] Using swcale to crop picture

[Eric Beuque]

Thank you for your answser!

I'm going to try libavfilter. I saw it seems to provide a filter algorithm,
so i guess libavfilter can replace libswscale? So what is the benefits to
use libswcale instead of libavfilter?


On Wed, Feb 13, 2013 at 6:35 PM, Paul B Mahol <onemda at gmail.com> wrote:

> On 2/13/13, Eric Beuque <eric.beuque at gmail.com> wrote:
> > Hi,
> >
> > I'm using avcodec and swcale to to display a MPJEG stream in a Qt
> > application.
> >
> > avcodec decode image as YUV image and swscale rescale it in a RGB32 image
> > to fit in the windows.
> >
> > I would like to provide a zoom feature, i so i am wondering if any way
> > exists with swscale to rescale only the selected region. For example, I
> got
> > an original YUV image as 1280x800 pixels, the destination widget is
> 640x480
> > pixels, but i want only to display the region [0,0] to [320,240].
> >
> > Is swscale able to to that? I have some difficulties to understand all
> > variables in the documentation.
>
> No, swscale is not supposed to do that.
>
> libavfilter have filters that do cropping, pading and etc...
> Also its not hard to do it manually.
>
> > Thank for your help
> >
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