Options for Distributing Spatial Audio
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Illustrations by Yoshi Sodeoka
This post is part of our Guide to Creating Spatial Audio Podcasts series. This guide covers the current state of spatial audio distribution, and shares options that podcasters can use to publish Dolby Atmos, Mach1, and ambisonic spatial content to the web.
Introduction to Spatial Audio Distribution
Right now, there’s no set standard for spatial audio distribution. How spatial experiences are published and listened to varies by platform, and by the type of audio experience that’s being shared — whether it’s music, film, or for our purposes, podcasts.
While the options for distribution have expanded in recent years, there are still limited options for delivering spatial audio-supporting podcasts and narrative audio. That’s in part because most podcast reader applications use web-based RSS feeds to pull in content, and these are optimized for small MP3 files. Spatial audio files are typically quite large, which makes it difficult for third-party streaming platforms to make them available to listeners. Additionally, proprietary formats such as Atmos require a hardware decoder which limits broad accessibility, particularly on the web.
As of the writing of this guide (October, 2022), most spatial podcasts are distributed through a mobile app offered to listeners via paid subscription. Apple Music, for example, hosts spatial content on its own servers and listeners must use their native app to play back audio. Tidal and Wondery also offer Atmos audio via native iOS apps. Native apps work well because they enable access to features such as hardware processing and head tracking that are not widely supported on the web.
While app-based experiences offer a dependable way to distribute spatial content, web support for spatial audio would make distribution much more accessible by providing access to wider audiences, reducing publication barriers, and offering support for a broader range of devices.
There are currently several options available for distributing spatial audio on the web:
Embedding Atmos on the Web
Atmos is supported on Safari for listeners using Apple devices such as iPhones and Mac computers, and on Windows for listeners using the Edge browser. If you’re using an iPhone or Mac and wearing AirPods while streaming Atmos spatial content from the web, then head tracking should work automatically.
Using an html audio tag, it’s possible to embed an Atmos file that Safari or Edge browser can play. The MP4 codec, available as an export option in the Dolby Renderer, helps reduce the file size while offering Atmos support in web browsers.
Embedding Mach1 on the Web
Mach1 offers broad web support across most devices through a web player that can use a phone's rotation to control the spatial rotation of the audio mix. Because of a limitation imposed by Apple, head tracking is not supported by web browsers. Here’s an example of how to use the Mach1 player in a web browser.
Embedding Ambisonics on the Web
Ambisonic audio is commonly used in VR applications such as Youtube360. For web playback, we’ve found the HOAST 360 player to be quite versatile. It supports higher-order ambisonics with up to 16 channels of audio..
R&D’s Spatial Audio Web Player
Combining several of these formats, we’ve created a web player (available on Glitch) that can be used to listen to spatial audio mixes on the web. It is intended for headphone-based audio experiences and works across both mobile and desktop.
Our player supports three spatial audio formats: Dolby Atmos, Mach1, and Ambisonics (as well as a fallback binaural mix). It can select the most suitable format for the user based on their listening device and the supplied mixes.
Our Glitch-based player works for spatial audio playback, and can be remixed on your own website. As seen in the code block below, we've embedded the player using an iFrame.
The Future of Spatial Audio
Spatial audio’s future depends on a few factors: Will head tracking become widely supported and gain mainstream adoption? Will there be a killer app or unmissable audio series that is built specifically for spatial audio?
While we’ll have to wait to see how things play out, at The New York Times, we’re committed to sharing our findings as we experiment with the possibilities of spatial audio podcasts and beyond. We’re excited to see how spatial mixing can be used in combination with other emerging mediums, such as in the story Hear a Harlem Choir Rejoice Again, which combines the emerging field of 3D photogrammetry, spatial audio and immersive storytelling to create one interactive experience. With these experiments, we’re starting to see a future unfold in which true spatial audio can be used to digitally recreate the powerfully emotional experience of, for example, being enveloped by the sounds of a church choir.