Re: Linux 2.6.9-ac3

[Luca Risolia <luca.risolia@studio.unibo.it>]

On Fri, 22 Oct 2004 15:16:39 +0200
Luc Saillard <luc@saillard.org> wrote:

> On Fri, Oct 22, 2004 at 02:30:36PM +0200, Luca Risolia wrote:
> > Either port the driver to V4L2, which handles decompression stuff well,

> no, it only provide a number (that needs to be reserved) to the user API, but
> if the user API doesn't exist, application will not support your camera. I
> can provide a .c and .h for the decompression module, but since the
> decompression table depend of the resolution,quality choose by the webcam
> (thinks as quality fine,normal,low). I can't provide with v4l2 a generic
> control for this.

Modify the V4L2 API by adding the correct generic interface.

> > or provide a separate downloadble GPL'ed module. Other drivers in the
> > mainline kernel observe this rule; the pwc case is not an exception.

> The driver, in it's current status, is GPL. Can you give me some examples
> about "other drivers" ?

At least two: w9968cf, ov511.

> > Also, this matter has been already discussed many times in the v4l
> > mailing list: no video decompression at all in kernel space, even if
> > *optional* through an *indipendent* module.

> It's easy for you to say that, because your driver returns a native format.
> Since nobody cares about webcam, and stream compressed, if today, i remove
> the table in the module, i'll wait one year ? two years for app that support
> my webcam ?

No, it's not easy for me to say that: the w9968cf driver is not really usefull
without the optional module available *outside* the kernel, since native UYVY
is not supported in userland at all. Furthermore, having had a separate module
for these things, is one more reason why none never patched any of the existing
applications.

Another example: sometime ago I had to patch the V4L2 API to add Bayer format
support to V4L2. This saved me from implementing colorspace conversion in the
sn9c102 driver. The patch was *one line* long and one of its results is that
now someone is working on gnomemeeting/pwlib to implement Bayer-to-* color
conversions that will make thousands of webcams work on Linux with this
application.

Regards,
	Luca Risolia