[Gridflow-dev] requests for GridFlow

Mathieu Bouchard matju at artengine.ca
Sun Mar 28 14:19:48 EDT 2010

On Sun, 28 Mar 2010, mescalinum at gmail.com wrote:
> On Sat, 2010-03-27 at 14:57 -0400, Mathieu Bouchard wrote:
>>> this driver is unsupported: it wants palette 8 instead of 15
>> I wanted to switch to libv4l in order to avoid this problem, but it seems
>> like I'm still not there yet, so, I'll try providing you code for that,
>> but I can't test it by myself, because I don't have the hardware for it.

To be really clear, "palette 8" code is for [#in videodev]. At this point, 
the [#in libv4l] code does not work at all.

> it says: UVC_Camera_[04f2:b172]
> in fact driver in use is uvcvideo

If you can get uvcvideo driver to work (without using LD_PRELOAD), then I 
have one less reason to finish coding [#in libv4l] ...

> now I get a different type of error:
> camera supports palettes : 8
> error: ioctl VIDIOCSCHAN: Invalid argument

starting with commit #5235, do you still see this error message ?

> but I'm unable to get any frames out of it. here's the error when I bang
> #camera:
> error: ioctl VIDIOCGMBUF: Invalid argument
> error: [#io.videodev in /dev/video0]: ioctl error
> ... you might be able to track this down from the Find menu.

Are the minimum and maximum resolution properly reported in the topright 
corner of [#camera] ?

Can you try various combinations of resolutions, with or without "transfer 
read" ? to do this, turn off the [metro], reclick on "device 0" (V4L1 
#0), select options, then reclick the [metro].

I get something like that with a camera that has an explicit framerate 
setting. It reports it has a maximum picture size of "480 640" (640x480) 
but when you try to get that while the framerate is set to 30, it 
complains a lot :

error: ioctl VIDIOCPWCSCQUAL: Invalid argument
error: ioctl VIDIOCSWIN: Invalid argument
camera supports palettes : 15
error: ioctl VIDIOCMCAPTURE: Invalid argument
error: [#io.videodev in /dev/video0]: ioctl error
error: ioctl VIDIOCMCAPTURE: Invalid argument
error: [#io.videodev in /dev/video0]: ioctl error
error: ioctl VIDIOCSYNC: Invalid argument

but now that I see it, I see it does not involve the GMBUF command at all. 
So, your problem might be something else instead.

GMBUF is used in [#in videodev]'s alloc_image() function, but only when 
"transfer mmap" is active (default). If you use "transfer read" it might 
circumvent that problem.

  _ _ __ ___ _____ ________ _____________ _____________________ ...
| Mathieu Bouchard, Montréal, Québec. téléphone: +1.514.383.3801

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