Dolby Atmos -- redefining sound
Dolby Atmos is indeed a revolutionary innovation, and it truly deserves the popularity it has gained in the last few years. Atmos is present in many forms and places, in theatres, home theatres, headphones and even smartphone speakers. There are also ways it set it up using a sound bar or traditional 2.1 sound set up. But, how could the same technology exist in something as fundamentally different as a phones and theatres?
Dolby has over the years given us the ways and means of storing, transmitting and reproducing high-quality sound. They specialise in the way sound is stored. The so called encoding products are used to capture and store; and subsequently reproduce sound originating from various angles. They started with Stereo -- simple two channel; progressing to 5.1 and 7.1 TruHD sound. Each new offering was a significant jump from the preceding generation.
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| Photo by Nana Andoh on Unsplash |
Dolby Atmos on the other hand is fundamentally different. Each of the previous products store sound originating from an explicitly defined direction. Stereo has left and right. 5.1 has Left, Center, Right, Left Surround, Right Surround and a Bass output. Atmos does not have explicitly pre-defined directions. The recorder is free to choose and define any angle in a 3D space and record audio data that pertains to that specific direction. This opens up infinite possibilities to capture or artificially produce sound.
Consider the following scenario in a movie or game:
A sports car, travelling north, is being chased by a cop car from the back and a helicopter just above the car. A cop appears from the North East, pulls out a gun and fires at the vehicle. Instead of the traditional pre-defined sound angles, Atmos is free to create its own channels with its own originating angle and distance from the audience. From this scenario 4 distinct channels can be dynamically created:
- Channel one: The runaway car's engines, due north, close to the audience.
- Two: The chasing cop car, due south with a medium distance.
- Three: The cop, due north-east, with a medium distance
- Four: The helicopter straight above, distant.
Sound can then be encoded for each of these channels. This method best captures the precise locations and intensities of each sound source, hence accurately recording exactly what the person in the car would hear.
Rendering or reproducing the sound is the essence of the Atmos magic. The individual channels are simulated using whatever equipment is available. A theatre with speakers in every direction will use only the speakers in those directions to generate sound, this is a big step-up from the older 7.1 standard which has a channel-limit and hence a direction-limit of 7-8. Each of the speaker arrays in the 7.1 system will have recorded all of the sounds from their particular vantage-points and hence will result in a slightly inferior sound quality in the individual channels (cross-channel distortion).
When playing Atmos content on a set-up, the decoder simulates all of the virtual channels it captures, taking into account the positioning of your speakers.You could arrange your speakers in anyway and so-long as the decoders knows the positioning, it will be able to decide which speakers to play sound originating from each of the virtual channels.
This truly gives you the best sound experience possible regardless of what your speaker set-up is. And with infinite channels, and infinite speakers, Atmos could be the very epitome of sound.
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