Video trace data from the Fairisle ATM network

This trace contains traffic measurements from the AVA-200 ATM Camera developed by Nemesys Research Ltd, and marketed by Fore Systems. Specifications for the AVA-200 can be obtained from Nemesys or Fore Systems (see end of this file). The AVA-200 (also simply called the ATM Camera) was set up to transmit video over the Fairisle network. The measurements were made using code written by Simon Crosby and other members of the Systems Research Group at the University of Cambridge.

This data is Copyright (c) Simon Crosby and Ian Pratt, 1994, University of Cambridge, UK. You may freely distribute this data but must retain the copyright notice.


Details of the Fairisle network and the Systems Research Group activities can be obtained from the ftp site at Cambridge:

ftp host is:
login:          anonymous
directory:      reports/ATM/docs-94-3/*


This is also available as the Systems Research Group Technical Note of March 1994 (the blue book), and can be obtained from the technical reports service at Cambridge: send email to

ATM camera traces

ftp host is:
login:          anonymous
directories:    fairdata/ava-traces/*
readme:         readme

Brief description of the traces in the subdirectories:

first-trace - the old ava trace which I took ages ago (1994)
misc - miscellaneous clips of video
        itn = ITN news including interviews and news clips

lethal-weapon-3 - traces from the movie of the same name, 
        at different peak rates

talk-show - an anglia TV talk show with voting 
        (so there were phone #'s displayed
        on the screen, with audience participation.

In general files are named as follows:

<name>.x.y = <name>.peakrate.fps (jpeg q 20, half field video)
the peak rate here is the number on the nrlwish slider bar.
If a file has a third component to name, that is just an instance number


Experimental data

This data currently comprises a single trace of ATM camera video. More data will be available soon. The camera was set up to transmit 25 frames per second, JPEG compressed, 24 bits per pixel colour video from various sources. In this experiment the ATM camera's spacing policer, which limits the peak emission interval of cells from the camera, was switched off. Thus the ATM camera transmits cells whenever they are ready to leave the device, and back-to-back cells are thus possible. The trace comprises the first 1000000 cells of the transmission, which included both action scenes (an explosion) and relatively static portions when credits were scrolling on the screen. The video data was transmitted from the AVA-200 to a Fairisle port controller which performed the measurements, and from there to a Sun Sparc 10 which displayed the video.

The JPEG picture size is 48x33 tiles (each tile is 8x8 pixels). Each tile is is compressed using a JPEG Q-Factor of 32, and transmitted with a single cell of tile overhead. The amount of information per tile will differ according to the video content.

The following is a graph of the trace data:

File format

The file exported for ftp is a gzip format compressed ASCII file. Use gunzip to uncompress the file and obtain the trace data. If you do not have access to gzip and gunzip, email and I will try to help you.

The file is in ASCII format, and each line (i>0) is a single measurement. Each measurement (i) records the time, in ticks, between the absolute cell number (i) and absolute cell number (i-1). Measurement (1) is therefore meaningless.

A tick is a fabric cell time on the Fairisle port controller. The fabric cell time in these experiments was set to 4.2666666 microseconds. A pair of back to back cells is recorded as an inter-arrival time of 1 tick.

The AVA-200

The AVA-200 is designed and manufactured by Nemesys Research Ltd in the UK. e-mail The unit is licensed for distribution by: K-NET Ltd in Europe. email: and Fore Systems, Inc in the rest of the world. email: