BT Sport LiveU LU70 Testing

The following recordings demonstrate the impact on link video quality for a number of combinations of LU70 delay (Profile in LiveU parlance) and resolution.

For events where we are sending a LU70 feed back to the 3xScreen MCR for the addition of live stream specific production and encoding, we normally use a 12 second delay and 1/4 HD – and we increase the delay beyond 12 seconds only if we have to add delay line type functionality to protect against bad language or other similar production issues.

Some LiveU users use 1/2 or Full HD and Automatic Video Resolution, for which the LU70 adjusts the bitrate depending on the underlying link conditions. From the 200+ LiveU feeds we have broadcast, we are convinced that 1/4 HD with a 12 second delay gives the best overall video performance. If the 3G connectivity is so poor that 1/4 HD is not supported, we use Web HD in preference to Automatic.

For ENG reporting where there is two-way live interaction between the studio and a field reporter, we use a mobile phone for IFB (rather than the LiveU’s IFB function) and we continue to use 1/4 HD – but with the delay decreased to 1.5 to 2 seconds depending on the 3G/4G performance in the area.

All LiveU links use H.264 High profile for video encoding and either 128 kbps or 64 kbps AAC for audio encoding – we only ever use 128k unless there is really bad 3G/4G connectivity.

We also always add additional bandwidth sources to the LU70 backpacks whenever we can. Many times we have had a great LiveU live link because we have also been connected on BT or other WiFi – or venue Ethernet or WiFi (each LU70 supports one WiFi connection and two Ethernet connections) while other LiveU users next to us have not been able to go live because they were only using 3G.

When we are in areas where there is little or no 3G/4G connectivity, we add Ka and Ku broadband satellite connections as Ethernet or WiFi bandwidth sources to the LU70 backpack.

When in Europe, we utilise a combination of pre-paid 3G SIM cards and Ka and Ku satellite depending on the event.

The addition of 4G SIMs has significantly improved LU70 performance. The added bandwidth is useful but the more important improvement is the better in-building performance of 4G over 3G.

This is our recommended mode for live streaming events

This is our recommended mode for ENG reporting

We don’t see the higher bandwidth requirements as the issue with this mode, in our opinion, the constraint of this mode is the processing power of the backpack when there is lots of movement – which causes blocking

This combination could be removed from the LU70s as far as we are concerned as it is not useable.

Automatic video resolution should generate an improvement in overall picture quality – but we aren’t convinced that it does.

The Balanced (4 second) Profile could be removed as far as we are concerned – it is too big a delay for live two-way ENG interactivity and too small a delay for maximising quality