dsd’s weblog

Lorin Olivier has created a kernel driver for his GL860 webcam. Lorin’s device is the 05e3:f191 variant, whereas mine is the more common 05e3:0503. There are differences between the devices that we don’t have much of a grasp on. The code we’ve written for each device is incompatible with the other, even though there are some protocol similarities.

Lorin reports that his driver works reasonably well with his device – it works with camorama, xawtv, ekiga, amsn, mplayer and xsane. He has also determined how to adjust various camera settings (luminosity, saturation, hue, sharpness, retrolighting, mirror effects, light source, AC power frequency).

Although Lorin doesn’t actually own an 0503 device, he’s attempted to implement support for it based on my earlier efforts. Given that I didn’t get very far, it probably doesn’t work that well. I haven’t had a chance to try it, but there’s no point me sitting on this any longer.

It’s in my git repository in the nvgl subdirectory:
git://projects.reactivated.net/~dsd/gl860.git (gitweb).

All credit goes to Lorin here – thanks! He’s done a great job, but do remember that its experimental code based on a reverse-engineered protocol, so don’t expect it to be flawless.

I’ve been making good progress on libusb-1.0, which has now entered beta. Features over libusb-0.1 include:

1. Asynchronous transfer capabilities (in addition to the synchronous style presented by v0.1)
2. Support for transfers to isochronous endpoints
3. Significantly faster bulk transfer performance for large transfers (several kilobytes or more)
4. Detailed API documentation
5. Power saving: on systems running recent Linux kernels, libusb-1.0 does not wake up all the USB devices plugged into the system during device enumeration
6. Greatly reduced CPU usage while waiting for results of bulk/interrupt transfers (libusb-0.1 was waking up every 1ms)
7. Thread safety

Backwards compatibility

As noted on the homepage, libusb-1.0 is entirely incompatible with libusb-0.1. However, it is designed to install in parallel, in the same way that you can have GTK+ 1.2 and GTK+ 2.x installed on the same system and in use at the same time.

I have also produced a compatibility layer which replaces libusb-0.1. libusb-compat-0.1 looks and smells exactly the same as libusb-0.1 (same library name, API, header file, etc) but internally it just converts libusb-0.1 calls to libusb-1.0.

This means that existing libusb-0.1 applications can take advantage of some of the new libusb-1.0 hotness mentioned above: improved bulk I/O performance, decreased CPU usage, power saving. These improvements appear without any modification to the original application, provided that the user has uninstalled libusb-0.1, and installed libusb-1.0 plus libusb-compat-0.1.

Status

I’m hoping this release will result in:

• More testing and adoption
• API review and feedback
• Ports to other operating systems. Only Linux is supported at the moment, but the library is structured internally for other ports to be written, and the internal API is documented in the source.

Further API changes may happen as a result of the above. This is not a finished product.

Source download

• libusb-0.9.0
• libusb-compat-0.1.0-beta1

My fprint fingerprint scanning efforts formed my final year Computer Science project at The University of Manchester.

The source code for this project has been available on SourceForge from early on (GPL-2/LGPL-2 licenses). I’ve now completed and submitted a comprehensive project report (similar to a dissertation) for academic assessment, and I’m making this available under a Creative Commons license. You can find the report here.

The report is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 UK: England & Wales License.

The academic project is now complete, but I plan to continue development as time permits. There is a lot to be done, and I have already made some good progress on moving libusb-1.0 closer to release.