V4L2 Camera interface for webcamxtra/JMyron

Steve Detwiler

http://piratestudios.com/steved
steved@piratestudios.com




Overview
======================================================================

This is a Video for Linux backend for webcamxtra and JMyron. I have
built this to allow the use of JMyron in Processing under Linux.

There are probably bugs and I'd like to hear about them if you find
one.

This requires a V4L2 driver and a camera that can output in YUYV
format. The UVC driver that ships with the current release of Ubuntu
(and likely other distros, too) supports many modern webcams.

I've tested with a Logitech Quickcam Communicate Deluxe.

This version is a rewrite of my earlier work. I have moved from V4L to
V4L2 to gain access to many more cameras. This release only supports
YUYV cameras. Previously I only supported RGB cameras. Eventually I'll
merge all of this together to provide autodetection based on your
camera.


Use at your own risk.



Prerequisites
======================================================================

A working camera with a working V4L2 driver on Linux that supports
YUYV. A list of many cameras that are supported by the UVC driver can
be found at:
  http://linux-uvc.berlios.de/

Processing-0135.

Installed JMyron for Processing following thier install
instructions. You can ignore copying their .DLL files.

This has been tested with webcamxtra SVN version 29.


Build Instructions
======================================================================

Get the current webcamextra source from SourceForge. For example, with
SVN use:

svn co https://webcamxtra.svn.sourceforge.net/svnroot/webcamxtra webcamxtra


The V4L interface is made of of the following files:
  v4l2Camera.h
  v4l2Camera.cpp
  
  A modified version of ezcam.cpp

  Makefile.linux

Copy these four files into the webcamxtra/ezcam directory.

Additionally copy the included copy of myron.cpp to the
webcamxtra/source directory.

Edit file Makefile.linux to specify the location of your copy of the
Java SDK and Processing.


From within the webcamxtra/ezcam directory, Run:

make -f Makefile.linux

This will build everything including JMyron. This isn't ideal because
it replicates many of the build commands from webcamxtra/source but it
works for the short term.

If everything went well, you will have a JMyron.jar and a
libJMyron.so. 



Installation Instructions
======================================================================

Ensure you have JMyron already installed and that you have followed
their instructions. You can ignore copying their .DLL files.

From the files you compiled or obtained with this release:

Copy the JMyron.jar to your processing/java/lib directory.
Copy the libJMyron.so to your processing/java/lib/i386 directory.

Run a JMyron example.


Revision History
======================================================================

20071011
Initial relese

20080113
Updated build instructions.

Included a modified copy of myron.cpp that includes <string.h> for
memcpy.

Removed dependency on old mrj.jar file from 0125.

20080203

Large rewrite to move to V4L2. 

Dropped support for V4L.

Added support for YUYV cameras. Temporarily dropped RGB support.

Updated Makefile.linux CLASSPATH. (Thanks hb).


Known Issues
======================================================================

RGB cameras are currently not supported.

I'm not happy with the current frame rate.