[Libav-user] Using swcale to crop picture

[Paul B Mahol]

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
>