The available data transmission rate offered by the network service is critical for compressed video quality. In the lossy compression techniques described in Chapter 2, the output bitrate of the encoder, and consequently the compression ratio, is highly dependent on the information `thrown away' at the quantisation stage. Larger quantiser steps lead to better compression ratio, and poorer quality of the reconstructed images. The latter can be thus used as a measure for the throughput requirements of the network service.