Auro-3D

Type of format	Uncompressed lossless audio format
First released	2005
Developer	Auro Technologies
Compression Type	CBR
Bitrate	27.648 Mbit/s (3.456 MB memory)
Channels	13.1
Bits	16-24
Sample	48 KHz, 96 kHz
Filename extension	.wav
Open Format?	No*
Free Format?	No
Magic Number	Wave: RIFF....WAVEfmt

Auro-3D is an immersive 3D audio format developed by the Belgium-based company Auro Technologies. It is not part of the BD specifications, but it is an optional codec. It is competing against Dolby Atmos or DTS:X.

Auro-3D is designed to be an extension of PCM rather than a completely new codec. It operates within the PCM framework, allowing it to be backwards compatible with standard audio setups. This means that when Auro 3D is played on non-Auro equipment, it can still output audio in the standard PCM format (playing the normal standard PCM channels and ignore Auro's additional channels and metadata), ensuring that the core audio experience remains intact. Auro 3D adds additional height channels and a more immersive sound experience by utilizing the existing PCM infrastructure, making it a versatile choice for modern home theater systems.

It is capable of handling 13 channels including the "Voice of God" channel at 96 KHz sampling rate in 24-bit resolution. It uses Microsoft WAVEX Channel Mask to identify the different channel roles used inside the WAV-files.

Only 18 channels are defined. Not all channels of 22.2 are defined, but all of the
AURO-3D channels (up to Auro 13.1) are, when using the TOP_BACK channel IDs
for the Height Surround channels.

For full compatibility, Auro-3D needs a certified AV receiver that uses Auro Engine, it's the core audio processing technology. It allows for the encoding, decoding, and playback of the Auro 3D audio format, enabling sound to be positioned in a three-dimensional space. This creates a more natural and enveloping audio environment, enhancing the overall experience in film, music, and gaming.

BD movies that use Auro-3D are often found in the European market, but music albums from 2L are the only ones that are sold in both Europe and North America.

Partial list of BD/UHD movies that use Auro-3D:

• Twister: Special Edition (2024) -  Germany
• Thunderbirds (2004 film) (2023) -   Germany
• Arthur the King (2024) - Netherlands
• The Beekeeper (2024) - Netherlands
• Everything Everywhere All At Once (2024) - Netherlands
  
• Becky 2 - She's back! aka The Wrath of Becky (2023) - Germany
• Devotion (2024) - Netherlands
• Ferrari (2024) - Netherlands
• MR-9: Do or Die (2024) - Netherlands    
• Talk to Me (2024) - Netherlands
• Sweet dreams (2024) - Netherlands
• Retribution (2024) - Netherlands
• The Collective (2024) - Netherlands
  

Note: Blu-ray.com has not listed all BDs that have Auro-3D audio.

Auro 3D is slowly being adopted in Europe, and gaining a niche in North America, not because of studio adoption but because of the expensive receivers and equipment. It is also unlikely it will be released in Japan and the rest of Asia.

Auro 3D is a great option if you want more of immersive audio within uncompressed PCM that pushes to the limits. Just be aware, that since it's based on PCM, it means it takes a lot of space. But if you're a developer that just want to use PCM with standard stereo or 5.1 surround sound then it would be wise to save money and not license Auro 3D for that. As there's multiple existing and free tools for standard PCM.

Footnotes

• *PCM is an open-format, but Auro-3D's extensions are not.

Links

• Auro Engine White Paper (PDF)
  
• Auro in multi-channel WAV files (PDF) 
• Auro-3D website
• Original research -Looked inside files from 2L's BD albums
  

Author(s) : Æ Firestone