AES Section Meeting Reports

Sala de Audio - September 27, 2011

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AES Mexico Section's monthly meeting took place last Tuesday, September 27th at Casa ARTeria's premises. This time they invited Carlos Watanabe, Dolby Laboratories' Regional Manager for Latin America and Adam Pinch, Support and Broadcast Systems Engineer at Dolby Laboratories, to talk to us about mixing in 5.1 for digital television (DTV).

Bego Echeverría, a member of our Student Section, volunteered to help in the development of the event. Without further ado, here's an inside look at AES Mexico's conferences.

"This is the second time I help at AES Mexico's monthly conferences. I am a first grade student at Sala de Audio, where all students get automatically registered as AES members. At first, AES seemed like a distant organization; going to the webpage and seeing all that information was a bit intimidating, but I've found out everybody is really accessible. All I had to do was send an email asking if I could volunteer to help and that same day I was recording the conference on the Anycast station! It is the console where video from the hall's various cameras and audio from a Yamaha SL9 (with signals from speakers' and audience's microphones as well as any other sources) are mixed.

Mintel Alonso is the engineer in charge of the event. Together with Abraham Martínez, his assistant, they taught me how the first thing that needs to get done is to prepare the space for the conference, setting up tables and chairs, mantelpieces, projectors, cables, microphones, consoles, etc. It's important to talk to the speaker or speakers: they might need to show a DVD or maybe use video and/or audio from a computer, etc. Then, after the conference, all the material is burnt to a DVD and everything needs to be put back where it belongs.

What I most appreciate from AES Mexico Section is that they don't mind that I'm only a first grade student and therefore don't know everything; they don't think less of you for that. They've received me very well and always appreciated and thanked me for my help. I know there is no better way to learn than listening to real experts, and I'm absolutely grateful with AES Mexico Section and my AES Sala de Audio-Mexico Student Section for allowing me to live these amazing experiences. Thank you so much!"

Carlos Watanabe and Adam Pinch talked about Dolby's DTV's systems: Dolby Digital and the newer, more efficient Dolby Digital Plus, which allows for more information to be coded into the same broadband. Both protocols carry metadata in the bit stream, and it is of vital importance to consider this metadata when making a 5.1 mix to ensure that all consumers get the best audible experience, be it a mono, stereo or surround experience.

To help achieve this, Dolby provides three systems: Dialogue Level (Dialnorm) measures signal level for different materials so that different programs can then be set at a more homogenous level. Dynamic Range Control allows for dialogue under a certain threshold to be amplified while dialogue over a higher threshold is compressed. The space between both thresholds is called the Dull Band, and it is where mixers want their dialogue to end up, so that it passes Dynamic Range Control unaltered. Then comes the downmix process. The information necessary for these three systems (the three "Ds") to work is encoded in the metadata.

Carlos and Adam stressed the fact that mixing for 5.1 is just like mixing for stereo: less is best. Don't succumb to the temptation of panning everything all around. Use movement panning sparingly, only when needed. Try to construct a supporting background for the action with the surround. Correct use of metadata makes it unnecessary to make two mixes (5.1 and 2.0) if the downmix process is monitored carefully.

Finally, AES Mexico Section thanked the speakers and the audience and invited us to their last monthly event of 2011 to be held, as usual, the last Tuesday of the month.

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AES - Audio Engineering Society