[PATCH] Add RGB555X and RGB565X formats to pxa-camera

[Guennadi Liakhovetski]

On Mon, 7 Sep 2009, Marek Vasut wrote:

> Dne Ne 6. září 2009 20:15:17 Guennadi Liakhovetski napsal(a):
> > On Sun, 6 Sep 2009, Marek Vasut wrote:
> > > Dne Ne 6. září 2009 18:52:55 Guennadi Liakhovetski napsal(a):
> > > > On Sun, 6 Sep 2009, Marek Vasut wrote:
> > > > > Ah damn, I see what you mean. What the camera does is it swaps the
> > > > > RED and BLUE channel:
> > > > > 15  14  13  12  11  10  09  08  07  06  05  04  03  02  01  00
> > > > > B4  B3  B2  B1  B0  G4  G3  G2  G1  G1  R4  R3  R2  R1  R1  --
> > > > > so it's more a BGR555/565 then. I had to patch fswebcam for this.
> > > >
> > > > Ok, this is, of course, something different. In this case you,
> > > > probably, could deceive the PXA to handle blue as red and the other way
> > > > round, but still, I would prefer not to do that. Hence my suggestion
> > > > remains - pass these formats as raw data.
> > >
> > > Which is bogus from the camera point of view.
> >
> > Not at all. This just means: the subdevice provides a pixel format, that
> > the bridge (PXA) knows nothing specific about, but it can just pass it
> > one-to-one (as raw data) to the user - don't see anything bogus in this.
> > Different bridges have support for different pixel colour formats, but, I
> > think, all bridges can pass data as raw (pass-through). Some bridges can
> > _only_ do this, so, this is actually the default video-capture mode.
> 
> But then you'll have to tell your software how to process the raw data (in what 
> format they are). If there was this RGB565X passthrough support, the software 
> could at least check if you are not forcing it to process nonsense.

There's no difference for user-space software. It requests BGR555 it gets 
BGR555 back, because that's the information the pxa driver will find in 
this format descriptor: if you take this data and put it in RAM in a 
certain way, you get BGR555.

Thanks
Guennadi
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Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/