[Nottingham] Mega-pixel webcams

Martin martin at ml1.co.uk
Wed Nov 18 16:36:18 UTC 2009

Jim Moore wrote:
> ayup Martin,
> First off the obvious - are you using a USB2.0 port with the proper
> drivers? Cameras will revert to VGA mode on USB1.1, it would appear
> that this is what's happened.
> I use a Sumvision Panther GX4 for my astro stuff (last year I was
> using a GX2), it does the full 4MP only due to the fact that I use a
> dedicated USB2.0 PCMCIA card (I know the onboard USB is only 1.1) and
> framegrab using GIMP. Don't ask me how or why (I don't actually
> know!), but Knoppix/Debian 5.x just seems to pick it up and run it at
> full rate so it's obviously using a common stock interface such as a
> BT878 (don't quote me on that, just using an example)*.
> *A little searching brought up the controller ID: it's a Microdia
> SN9C120, so do the following I found (for Ubuntu 9.x, YMMV):

Yep. That's the webcam from your recommendation from long long ago, as
bought from your favourite local shop.

And it's definitely found as a usb 2.0 device:

klogd: usb 2-6.4: new high speed USB device using ehci_hcd and address 14
klogd: usb 2-6.4: New USB device found, idVendor=058f, idProduct=6254
klogd: usb 2-6.4: New USB device strings: Mfr=0, Product=0, SerialNumber=0
klogd: usb 2-6.4: configuration #1 chosen from 1 choice
klogd: hub 2-6.4:1.0: USB hub found
klogd: hub 2-6.4:1.0: 4 ports detected
klogd: usb 2-6.4.1: new high speed USB device using ehci_hcd and address 15
klogd: usb 2-6.4.1: New USB device found, idVendor=0c45, idProduct=6242
klogd: usb 2-6.4.1: New USB device strings: Mfr=0, Product=1, SerialNumber=0
klogd: usb 2-6.4.1: Product: USB20 Camera
klogd: usb 2-6.4.1: configuration #1 chosen from 1 choice
klogd: gspca: probing 0c45:6242
klogd: sn9c20x: MT9M111 sensor detected
klogd: gspca: probe ok

cheese works very well but only picks up 640x480 max. As do camorama and

I'm using Mandriva2010 and one quirk is that I need to preload a convert
driver to convert from the compressed output of the webcam to something
that other applications can recognise:

LD_PRELOAD=/usr/lib64/libv4l/v4l1compat.so cheese

LD_PRELOAD=/usr/lib64/libv4l/v4l1compat.so camstream

LD_PRELOAD=/usr/lib64/libv4l/v4l1compat.so camorama

I'm guessing that the gspca "v2" drivers are being used whereby the jpeg
decompression is being done outside of the kernel module.

GIMP doesn't find the webcam regardless of whether I do the preload
trick or not. Does it need a plugin to pick up webcams?

So what's 'special' about your pcmcia usb adaptor? Are the drivers for
that doing the 'something special'? Or how do you break out of the VGA


Martin Lomas
martin at ml1.co.uk

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