The WWDC25 video and notes titled “Learn About Apple Immersive Video Technologies” introduced the Apple Spatial Audio Format (ASAF) and codec (APAC). However, despite references throughout on using immersive video, there is scant information on ASAF/APAC (including no code examples and no framework references), and I’ve found no documentation in Apple’s APIs/Frameworks about its implementation and use months on.
I want to leverage ambisonic audio in my app. I don’t want to write a custom AU if APAC will be opened up to developers. If you read the notes below along with the iPhone 17 advertising (“Video is captured with Spatial Audio for immersive listening”), it sounds like this is very much a live feature in iOS26.
Anyone know the state of play? I’m across how the PHASE engine works, which is unrelated to what I’m asking about here.
Original quote from video referenced above: “ASAF enables truly externalized audio experiences by ensuring acoustic cues are used to render the audio. It’s composed of new metadata coupled with linear PCM, and a powerful new spatial renderer that’s built into Apple platforms. It produces high resolution Spatial Audio through numerous point sources and high resolution sound scenes, or higher order ambisonics.”
”ASAF is carried inside of broadcast Wave files with linear PCM signals and metadata. You typically use ASAF in production, and to stream ASAF audio, you will need to encode that audio as an mp4 APAC file.”
”APAC efficiently distributes ASAF, and APAC is required for any Apple immersive video experience. APAC playback is available on all Apple platforms except watchOS, and supports Channels, Objects, Higher Order Ambisonics, Dialogue, Binaural audio, interactive elements, as well as provisioning for extendable metadata.”