[Ffmpeg-devel] crop, pad, and v4l grabbing

Erik Slagter erik
Tue May 16 11:54:32 CEST 2006


On Mon, 2006-05-15 at 14:23 +0200, Luca Abeni wrote:

> > If you like a challenge: use the hardware cropping/scaling capabilities
> > of the cards. At least the saa7134's driver has this exposed using the
> > crop ioctl. Maybe other types feature this as well nowadays.
> Well, that's an intereting challenge :)
> 
> Some time ago I considered implementing support for hardware cropping,
> but it turned out that my capture card (or the card's driver, I do not
> know) do not support such feature...

Probably the driver. AFAIK all non-ancient cards support hardware
scaling.

> (or maybe I misread the v4l2 spec, and I did not setup the card
> properly)

Hmmm. I had it working (with the saa7134, at least). But I confirm that
the v4l2 spec isn't always 100% clear and sometimes drivers simply do
not comply.

> For the moment, I'll just commit the simple patch I posted, so that
> ffmpeg's cropping & padding work also when capturing video from a v4l(2)
> card.

Sure.
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