Re: [PATCH 2/4 v4] i.MX31: Image Processing Unit DMA and IRQ drivers

From: Dmitry Krivoschekov
Date: Tue Dec 23 2008 - 06:32:27 EST


Sascha Hauer wrote:
> On Tue, Dec 23, 2008 at 01:09:10PM +0300, Dmitry Krivoschekov wrote:
>> Robert Schwebel wrote:
>>> On Mon, Dec 22, 2008 at 07:37:53PM +0100, Sascha Hauer wrote:
>>>> Another thing is the overlay framebuffer. I think it's mainly useful
>>>> to display video streams.
>>> Right. The idea is that you can push a video stream into /dev/fb1 (for
>>> example by using the gstreamer fbdev sink) while displaying widgets from
>>> a GUI toolkit on /dev/fb0.
>>>
>>>> Maybe it's better to implement this as a v4l device as unlike the
>>>> framebuffer API the v4l API is designed to handle different image
>>>> buffers.
>>> Huh? v4l is image-frames-to-userspace, not vice versa.
>>>
>> ...and vice versa too, v4l2 is not about input devices only but it is
>> also related to output devices, v4l2 spec even has a special chapter
>> dedicated to overlays [1]. Moreover, you can find such a driver within
>> Freescale's BSP [2]. Another example is Omap's videoout driver [3].
>
> Are you aware of any application making use of this feature?

IIRC, mplayer is able to output on a v4l2 device. Also, Freescale's
i.MX31 ADS BSP contained a bunch of V4L2 unit tests, including v4l2 output.

Dmitry


[1]
http://www.freescale.com/webapp/sps/site/overview.jsp?code=CW_BSP_ARM&fsrch=1
>
> Sascha
>

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