zc3xx webcam crashes on in-focus pictures

zc3xx webcam crashes on in-focus pictures

[Johannes Bauer]

Hi list,

the problem I'm having sounds really weird and strange, please bear with
me -- I do not know who else to ask or what to search for.

I have a Logitech Labtec webcam:

Bus 001 Device 012: ID 046d:08a2 Logitech, Inc. Labtec Webcam Pro

Which I use with the zc3xx driver on a 2.6.34 Linux:

usb 1-3.2: new full speed USB device using ehci_hcd and address 12
gspca: probing 046d:08a2
zc3xx: probe sensor -> 000e
zc3xx: Find Sensor PAS202B
input: zc3xx as /devices/pci0000:00/0000:00:1a.7/usb1/1-3/1-3.2/input/input7
gspca: video0 created
gspca: found int in endpoint: 0x82, buffer_len=8, interval=10
gspca: probing 046d:08a2
gspca: probing 046d:08a2

I'm using mplayer for playback. This works nicely for the most part.
However, as soon as I get things in focus (or make images of things that
have sharp edges), the driver chokes -- mplayer just displays

v4l2: select timeout

And no more frames appear. As soon as I put the pictures back out of
focus, frames are updated again.

I've noticed this problem about a year back when I tried automatic
recognition of QR codes with that camera. Since QR codes basically
consist ONLY of sharp edges (black/white), the camera totally choked
upon shown one. Back then I ditched the whole project and found another
solution.

Now I just tried to hook the camera up to my microscope for fun. As a
test image, I made an image of a ruler. It worked pretty nicely, but you
guessed it: As soon as I put the image in focus, the camera chokes.

Has anyone ever heared of a similar problem with that driver? Or may
that even be a hardware fault? Lastly, can anyone recommend a
high-quality webcam that runs smoothly on Linux?

Best regards,
Joe

Re: zc3xx webcam crashes on in-focus pictures

[Jean-Francois Moine]

On Sun, 11 Dec 2011 12:59:39 +0100
Johannes Bauer <dfnsonfsduifb@gmx.de> wrote:
	[snip]
> I have a Logitech Labtec webcam:
> 
> Bus 001 Device 012: ID 046d:08a2 Logitech, Inc. Labtec Webcam Pro
> 
> Which I use with the zc3xx driver on a 2.6.34 Linux:
> 
> usb 1-3.2: new full speed USB device using ehci_hcd and address 12
> gspca: probing 046d:08a2
> zc3xx: probe sensor -> 000e
> zc3xx: Find Sensor PAS202B
> input: zc3xx as /devices/pci0000:00/0000:00:1a.7/usb1/1-3/1-3.2/input/input7
> gspca: video0 created
> gspca: found int in endpoint: 0x82, buffer_len=8, interval=10
> gspca: probing 046d:08a2
> gspca: probing 046d:08a2
> 
> I'm using mplayer for playback. This works nicely for the most part.
> However, as soon as I get things in focus (or make images of things that
> have sharp edges), the driver chokes -- mplayer just displays
> 
> v4l2: select timeout
> 
> And no more frames appear. As soon as I put the pictures back out of
> focus, frames are updated again.
	[snip]

Hi Joe,

Your problem seems to be tied to the JPEG compression. It should have
been fixed in June, for the kernel 3.1.x (commit 93604b0fdde32). If you
cannot update your kernel, you may try the gspca test version from my
web page (see below).

Best regards.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

Re: zc3xx webcam crashes on in-focus pictures

[Johannes Bauer]

Forgot to CC the list, here it goes...

Hi Jef,

Am 13.12.2011 11:32, schrieb Jean-Francois Moine:

> > So, I added controls to modify these registers in the version 2.14.5
> > I've just uploaded.
> >
> > The values may be modified by programs as 'v4l2ucp' (control only),
> > 'vlc' or my program 'svv'. Note that changing the register values works
> > only when capture is active (the values are reset at capture start
> > time).

Wow - you, Sir, are good! I am really impressed.

After installing the package, I saw that the values are initialized at
R7 = 0, R8 = 2. Sharpness is initialized to 2.

As soon as I changed R7 to 1, it worked perfectly. This also yielded a
perfect image quality (at some settings there was weird noise patterns).
>From 34..50 I could reproduce the bug again.

Also when I raised the sharpness to the max level of 3, the bug appeared
again.

So thank you again for your solution and my kudos again. Awesome! Also,
svv is a really neat tool, I'll surely use that in the future.

Best regards,
Joe