LAS VEGAS, NEVADA - DECEMBER 2009: UK-based satellite broadcaster Sky made broadcasting history over the summer, transmitting completely live for the first time ever a series of weekly television plays in high-definition, with a 5.1 surround soundtrack. Helping to create the 5.1 ambience during transmission of the Sky Arts channel series from Sky Studio 6 in Isleworth, London, was one of the broadcaster's eight recently acquired SoundField UPM-1 stereo-to-5.1 upmix processors. Specifically, the UPM-1 was used to process stereo spot effects, atmospheres, and pre-recorded music from the Sky audio libraries so that this content would be transmitted in full 5.1.

Originally designed to allow HD broadcasters to create 5.1 audio in real time from stereo-only archive material, the UPM-1 has been used extensively on live broadcasts since its arrival at Sky's HQ in the early summer. However, the series of live plays, transmitted as Sky Arts Theatre Live! marked the first occasion of the UPM-1 being used on a drama production.

The Sound Supervisor for the entire series was Sky's Carlton Waghorn, who explained some of the thinking behind the use of the UPM-1. "This was a very exciting project, blending some of the old skills from the heyday of live black and white transmission with the latest in 5.1 surround and high-definition broadcast technology.

"It was a question of trying to make the most of the 5.1 experience for our viewers. We produced some opening titles with 5.1 theme music, and were creative with the mics, but I was concerned that the viewers would get the opening titles in 5.1, a round of applause in surround at the start, and then an essentially 'flat' stereo performance until the applause at the end, with the exception of the commercial breaks. We wanted to avoid that," Waghorn says.

The approach was to put all of the library-sourced atmospheres and most of the spot effects and occasional stock music, which were from stereo libraries, through the recently installed SoundField UPM-1. "It's a great piece of kit," explains Waghorn. "It brought the whole thing to life, and meant we had some 5.1 content all the way through the performance. I know some people regarded it as a post-production tool when it was announced, but it is adaptive and designed to be used in real-time, and we were making the most of that.

"To be honest, I will be running lots of things through it over the next few years, because all of our cart, music, and effects libraries are still in stereo, as far as I know, and if you want to make those work in 5.1 broadcast, the UPM-1 provides a really good way to do it."

"The other thing that's great about the UPM-1 is that it produces very phase-coherent, stereo-compatible results," adds Keith Lane, Sky's operations manager. "We need backwards compatibility. It's no use doing 5.1 mixes if they sound terrible when they're folded down to stereo. We look forward to doing more live HD drama in the future, and when we do, the UPM-1 will be an important part of that," Waghorn concluded.