On Mixing Surround Audio for HD

Billy Gardner has 14 years experience as a premier audio mixer and sound designer. His work ranges from promo campaigns and commercials to series, specials and features for prominent network and cable stations including ABC, CBS, NBC, PBS, ESPN, The History Channel, Discovery Kids, SciFi Channel, VH1, and MTV. While his PostWorks colleagues completed HD editorial and finishing services on the video, Gardner mixed the audio for the Ford Ironman World Championship, which aired in HD (for the first time) on NBC on Sat., Dec. 9.
Q: How were the audio elements for the iron man event recorded?
A: Although the Ford Ironman World Championship was shot and aired in HD this year, it was decided not to mix it in 5.1. This would have added one more new unknown into the mix. That being said, I traveled to Kona to collect a sound library in stereo. In the past, I had compiled mono sounds from the camera masters, but by recording and compiling a stereo effects library of the actual place and event, we were able to create a richer environment and experience for the viewer. Each and every shot in the show is multi-layered with my recorded sounds on top of the original sound from the cameras. I found that by keeping some of the original sound, it helps create a believably realistic soundtrack.
Q: What was the biggest challenge in capturing the surround sound elements?
A: The biggest challenge was to make sure I had everything I would need for not only a stereo broadcast, but for a future 5.1 broadcast as well. In addition to the normal sounds one might expect from the race, I spent a lot of time in my car one quiet night with my window down at different heights and with the mic at multiple distances to get stereo car-wind noise that was not distorted. I would drive to the top of a hill and coast down to avoid engine noise, but I also recorded the interior of the car with the windows up. All of this added together made for a realistic experience. After last year’s show, which was the first to take advantage of this library, I remixed the show in 5.1 as a test, which worked very well. By putting the bike sounds up front, the car interior noise in the rear and surrounding the listener with the car-wind, which was also added to the LFE sub channel, it made for quite an impressive experience. Needless to say, I can't wait for the day that viewers will be able to hear a 5.1 mix of the Ford Ironman World Championship.
Q: Are most HD productions recording in Dolby Digital 5.1 surround sound or not? Explain who's doing it.
A: Most HD productions are not recording in 5.1. Some programs, such as live sporting events or shows with a live studio audience, I believe are doing something to achieve a surround crowd, but I'm not sure if they are being recorded in 5.1 or simply panned and mixed to appear that way in a 5.1 mix. Almost all of the shows I see come into post to be mixed in 5.1 are coming in no different than when I mix in stereo, which means getting an OMF file from an Avid NLE with mono voices, mono natural sound and stereo music. I then may add additional stereo effects to the program, and pan and mix in such a way to create a 5.1 mix. With some larger productions that are scored by an actual composer, the composer will supply me with either 5.1 mixes of his music or simply stereo stems of his mix rather than just a stereo mix. The latter seems more common. Instead of a full stereo mix, the composer will give me a stereo mix of the percussion, strings and synth. In the final post mix of the show, I may put the percussion up front and in the LFE sub channel, I may put the strings up front and bleed them into the rear a little and I may put the synth mainly in the rear bleeding into the front a little.