RabbitMQ

This page describes Camstream, an example AMQP client program that demonstrates some of the features of RabbitMQ.

Table of Contents

Camstream - Streaming video over AMQP

Camstream uses AMQP to route live, streaming video from one or more webcams to one or more displays. A capture program injects frames into a named AMQP fanout exchange, and a corresponding playback program uses an anonymous auto-delete queue to retrieve a stream from a named exchange.

Camstream network diagram

In this way, Camstream behaves similarly to a video-enabled IRC, where an exchange models an IRC channel.

Live Demo

You can launch camstream via Java Web Start:

If you accept the default settings for the host name and channe name, the programs will connect to a public demo server.

Broker configuration

In order to run camstream on your own AMQP broker installation, you need to configure the broker to have

  • a user camstream with password camstream,
  • a virtual host /camstream,
  • permissions that grant the camstream user full access to the /data realm of the /camstream virtual host.

Follow the instructions in the admin guide for configuring a RabbitMQ broker. Here is transcript of the required commands: 

$ rabbitmqctl add_user camstream camstream
Creating user "camstream" ...done.
$ rabbitmqctl add_vhost /camstream
Creating vhost "/camstream" ...done.
$ rabbitmqctl map_user_vhost camstream /camstream
Mapping user "camstream" to vhost "/camstream" ...done.
$ rabbitmqctl set_permissions camstream /camstream /data all
Setting permissions for user "camstream", vhost "/camstream", realm "/data" ...done.

Running Camstream

This section describes how to run Camstream from the command-line, if you chose to download the software or compile the source code

Camstream is made up of two separate classes of program: the capture programs, for various architectures, that capture video frames and inject them into an AMQP broker; and the display program, written in pure java, that retrieves and displays video and provides a basic text chat application.

While any platform can play back video using camdisplay, only platforms supported by either the Java Media Framework (JMF) or by a special driver can capture video for injection into the AMQP network.

The JMF supports Windows, Linux and Solaris. You can download the JMF for your platform from here. Both Mac OS X and Linux also have their own special drivers. The following table summarises the various platform options:

Platform Windows Mac OS X Linux Other JMF
Capture program camcaptureJMF camcaptureOSX camcaptureLinux,
camcaptureJMF 		camcaptureJMF
Display program camdisplay camdisplay camdisplay camdisplay

Running capture programs

The capture programs are camcaptureJMF, camcaptureOSX, camcaptureLinux, in Java Media Framework, Quicktime and Video4Linux variants respectively.

The Quicktime variant is for Mac OS X machines, running OS X version 10.3.9 or greater.

The Video4Linux variant is an alternative to the JMF variant for Linux machines with V4L-compatible webcams. Use this if you do not wish to install the JMF for Linux.

You can either start the programs without command-line arguments, which will open a window asking for the startup parameters the program needs: 

$ ./camcaptureJMF
$ ./camcaptureOSX
$ ./camcaptureLinux
C:> camcaptureJMF.bat

or you can supply the following command-line arguments: 

./camcaptureXX hostname exchangename routingkey framerate x-res y-res

hostname
The host name of the AMQP server to route video through.
exchangename
The exchange (i.e. "channel") to publish video to. This is a similar notion to IRC's "channel" concept.
routingkey
The AMQP routing key to use for each transmitted piece of media. This is a similar notion to IRC's "nick" concept - a personal identifier for use within a channel.
framerate
Defaults to 5 fps. This limits the maximum number of video frames per second the program will capture and transmit.
x-res and y-res
Defaults to 176x144. These parameters configure the resolution of the video stream to be captured and transmitted. Note that if a resolution is selected that is not supported by the camera, it will silently ignore these settings.

Running the playback program

The playback program is called camdisplay, and runs on any Swing-supporting Java runtime, including those for Windows, Linux and Mac OS X. 

./camdisplay hostname exchangename routingkey

hostname
The host name of the AMQP server to retrieve video from.
exchangename
The exchange (i.e. "channel") to bind our AMQP queue to.
routingkey
The AMQP routing key to use for each transmitted piece of media. This is a similar notion to IRC's "nick" concept - a personal identifier for use within a channel.

Note that the framerate is entirely controlled by the intersection of the capture program's maximum framerate and the available downstream bandwidth between the AMQP server and the camdisplay client.

RabbitMQ™ is a Trademark of Rabbit Technologies Ltd.