[linux-dvb] Re: RFC 0.3: MPEG encoding and decoding V4L2/DVB API additions

Mauro Carvalho Chehab mchehab at infradead.org
Sun Feb 18 17:54:47 CET 2007


> 6) Scaling and positioning of the video
> 
> The cx23415 can take the MPEG stream and scale it to an arbitrary width 
> and height and position it at anywhere in the TV-out screen. So you can 
> get effects like having the MPEG output to the top left corner and an 
> OSD in the lower right corner.
> 
> With VIDIOC_S_FMT I can set the width and height, but there is no 
> provision for an x and y coordinate. Can the struct v4l2_pix_format be 
> expanded to include this? It would be the logical place for it. For 
> most devices the x and y would always to 0, so I don't think it would 
> be a problem.

Hmm... Please correct me if I'm wrong, but does it make sense to use non
0 x,y if you don't have the OSD API defined? 

I suspect that this feature is really interesting with OSD. If so, maybe
we can discuss it a little later, together with OSD API. For example, we
may thing on one tv out positioning API, generic enough to be used by
both mpeg output and osd. Something like:

struct {
	enum  type {
		OSD,
		VIDEO
	}
	int	x,y;
}

-- 
Cheers,
Mauro




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