Channel change time and image quality are central to TV service suppliers in today's competitive market. Witbe carried out a study of digital TV services (via DSL, cable, FTTH,
satellite and DTT), looking at 30 operators in 16 countries on 4 continents. The average channel change time measured using P+/P- was 1.9 seconds. If the user chooses the channel number,
the change time came out at 3.4 seconds with a more uniform distribution than in P+/P- mode.
Witbe noted important variations between operators but also between technologies.
Witbe distinguished amongst these factors:
– The broadcasting technology: satellite is twice as slow as IPTV
– The maturity of the services tested: services launched recently are often slightly slower
– The IPTV system used: for example, Microsoft Mediaroom platforms have the best results in P+/P- mode, with an average of 0.6 seconds. Channel change times of 0.7 seconds can be measured on other platforms.
– The performance of the decoder and notably the buffering policy
– The presence of retransmission mechanisms or forward error correction which, when they are not
combined with rapid channel change systems, can degrade the quality