This pattern tests the effectiveness of the
MPEG compression. MPEG works by only encoding
the parts of the picture that are changing from
one frame to the next, and uses some predicting
algorithms to predict the next frame.
There is some white noise on the test
pattern which completely flummoxes the encoding
procedure because white noise is random and
takes up a lot of bandwidth to encode. The
outcome of this is that the rotating circles at
the bottom, which are moving from side to side,
flicker quite badly.
Most of the chart moves in some way, to try
and catch out the MPEG, but there are some
familiar parts of the chart, notably the
greyscale (which moves) and the gratings (which
There is also a small box which changes
between "IfN" whatever that stands for) and
what looks like a really old Radio Spares (RS)
Click on the chart to see a movie of this
in action! However, as it is encoded in
MPEG and it looks slightly corrupted on a
Digibox, you can't expect much!