On Thu, 2002-03-21 at 14:10, Joe Burks wrote:
> There are a lot of good reasons for a camera *NOT* to do all the filtering in 
> firmware.

And for exactly that reason, you shouldn't do it in a base lib as well,
but let the application find a suitable way of doing it, as it feels
like doing itself. See Alan's response.

> How is it done now?  The reccomendation I saw was "we could just let xv do 
> it".  How many apps are perfectly happy to let xv manipulate their images for 
> display?

How many people don't have Xv? I don't (nvidia's XFree driver doesn't do
Xv and I don't want to run nvidia.com's driver). Other people feel fine
with it. Hence my point, everyone's needs are different!

> How many current v4l applications support gamma correction?  How do I express 
> the need for this sort of post processing to the v4l application?  Why aren't 
> the application developers pumping out more v4l apps with advanced post 
> processing capabilities?  How about obvious postprocessing tasks like 
> rotation?  It's pretty easy to rotate a camera 90 degrees to get better scene 
> composition, few v4l apps have that feature.  Heck my live webcam is 
> mounted to a bracket on the ceiling, that image needs 180 degrees of 
> rotation.  If I wanted to stream live video from that camera, it'd look 
> horrible.

So, if it isn't there, hack it in the applications. But don't let the
driver or quasi-driver (libv4l) do it. What about closedsource apps (not
that we care) that have terribly fast asm/mmx/sse-algorithms (but
proprietary). Should we just make their live impossible?

> If we would want the application to have the option of saying "give me an 
> unfiltered video stream", I have no problem with that.  Then they could use 
> their own gamma, rescaling, contrast, whatever.  But I'm going to bet 
> that few applications are going to make use of it.  I base this on the fact 
> that the apps available now could do this and generally don't.

Generally because they're all 1-man projects (or so). If there was one
bigger project, I bet it'd be interested in doing their own post-capture
filtering. So this is a pretty good idea (tm), imho.

Ronald

-- 
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