​SPATIAL AUDIO OVERVIEW
At its essence, Spatial Audio is the creation of a 3D or immersive sound environment through the use of traditional surround speakers with additional height speakers or through binaural headphones.

Though spatial audio in various forms has been around for decades and Dolby Atmos had become synonymous with cinema and movie soundtracks, it wasn't until late 2020 Apple when announced their "Spatial Audio" branding of Dolby Atmos® that spatial audio and other codecs (as below) then became rapidly adopted across the wider audio industry.

There has simultaneously been a marketing-led increase in the hype, confusion and misinformation about this exciting audio revolution.  As Arvus is developing format / codec agnostic hardware post-production platforms, we felt it was our responsibility to share simple unbiased information about the many types of codecs available so as to help the industry choose which system best meets their workflow needs and commercial objectives.

We hope the below overview helps you navigate this fast evolving audio arena*.
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How is Spatial Audio different?
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Though there is a plethora of audio systems from mono, stereo, 4-track, Dolby surround, DTS etc. the primary systems of audio can be seen as the following:
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  • Stereo Sound is a two-channel audio system where sound is divided into left and right channels. It gives a sense of width but doesn't provide much sense of depth or any height.
 
  • 5.1 (or 7.1) Surround Sound involves multiple speakers placed around the listener. It includes front, rear (and in case of 7.1, side) channels, as well as a subwoofer for bass. It provides a sense of width and depth but doesn't incorporate height channels.
 
  • Spatial Audio, also known as Immersive Sound, refers to techniques that create a three-dimensional sound field, providing a sense of width, depth, and height. It uses discrete channels (as stereo and 5.1-7.1) or object-based audio (see further), and can make it feel like sound is coming from all around you, including above and below.
 
  • Object-Based Audio treats individual sounds as "objects" that can be positioned anywhere in a 3D space. The position of each object is defined within a given space and the codec renders the sound environment in real time depending on how may speakers are defined for said environment e.g., 5.1.2, 7.1.4 or 9.1.6 (with the last digit being the number of height channels). This enables the intent of the sound designer to be accurately reproduced no matter the size of room or system configuration.​
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  • Binaural Audio is not a "proprietary codec" but a method of using phase/timing of stereo audio signals sent to Headphones to create a 3D spatial illusion.
The Main Format / Codecs in Spatial Audio:
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Key differences between the Format / Codecs:
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  • Object-Based vs Channel-Based: Dolby Atmos, DTS:X, MPEG-H 3D Audio, Sony 360 Reality Audio and AURO-3D* are object-based or hybrid channel/object-based, meaning they can position sound anywhere in a 3D space. AURO-3D and MPEG-H also provide channel-based immersive sound, where sound is mixed into specific channels or layers. Ambisonics is channel-based only.
    *Depends on which codec is used: Auro-Codec = channels; Auro-Cx and AuroMax = hybrid​
 
  • Height Information: Dolby Atmos, DTS:X, AURO-3D, and MPEG-H 3D Audio all support overhead sound natively. Sony 360 Reality Audio can reproduce a sense of height through headphones using HRTF (Head-Related Transfer Function) techniques. Ambisonics requires additional processing to reproduce height information. (all Ambisonics orders support height information natively, but it is not always used in the decoder)
 
  • Flexibility: Dolby Atmos, DTS:X, MPEG-H 3D Audio, and Sony 360 Reality Audio can create an immersive audio experience regardless of the number or placement of speakers, as long as the playback system supports these formats. Most formats require a specific speaker setup to perform optimally, but in many cases a combined speaker setup is possible as well.
 
  • Ideal Application: Each formats / codec has its own speciality. Dolby Atmos, AURO-3D and DTS:X are popular in home theaters and cinemas, for movies and music. Sony 360 Reality Audio is optimized for music*, creating a "live performance" feeling. Ambisonics is commonly used for VR and 360-degree videos, and MPEG-H 3D Audio is mainly used in broadcasting.
    *AURO-3D is also used for music a lot (in fact, there is more classical music in Auro than in Atmos or Sony). Atmos for Music is also popular.
 
  • Maximum Channels:
    • Dolby Atmos, AURO-3D (AuroMax) and DTS:X Pro support up to 128 audio tracks (or objects) in cinema (using the standardised SMPTE IAB format)
    • DTS:X supports up to 32 discrete channels
    • AURO-3D supports up to 13.1 playback channels
    • MPEG-H 3D Audio supports up to 64 discrete channels.
    • SONY - 360 Reality Audio's max channels are not specified (as it's more about object positions in the spherical sound field)
    • Ambisonics depends on the order (First order has 4 channels, second order has 9, etc.)


​*We will continue to refine and expand the information on this page. Feel free to contact us with suggestions 
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