KHR_audio

[robertlong]

This PR proposes a number of changes discussed during the OMI/Khronos 3D Formats Working Group Meeting on 3/23/2022 with @robertlong, @fire, and @lyuma in attendance.

Khronos is eager to unify the MSFT_audio_emitter and OMI_audio_emitter extensions into a single common KHR extension.

Since OMI_audio_emitter is effectively a subset of the MSFT_audio_emitter features, there are no additional features to be added to OMI_audio_emitter. Only changes to how the JSON schema is defined, likely some clarifications to the spec in future PRs, and a change in extension name to reflect that this will be the official Khronos ratified extension.

Here are the changes to the schema:

• The extension has been renamed from OMI_audio_emitter to KHR_audio. KHR_audio both reflects the intent for this to be an official Khronos ratified extension and a more general audio extension to form the basis for additional extensions to provide features such as audio mixing, animation/one shot triggering of clips, additional audio format support, etc.
• audioEmitter / audioEmitters properties have been renamed to emitter/emitters. The audio prefix is redundant because these properties are nested under KHR_audio
• Positional audio emitter properties are moved into the positional object. This object can be added to audio emitters when it is of type positional.
• Fixed a typo in the schema where scenes defined their emitters property as nodes instead of emitters

We will discuss these changes in our weekly glTF Working Group meeting tomorrow and decide if we'd like to take this to a vote in the following meeting. If that passes, we'll go forward with submitting this as a PR to the Khronos repository.

[robertlong]

The vote to approve submitting this proposal to Khronos and moving our efforts to a unified KHR extension has passed:

[robertlong]

Submitted to Khronos for review here: KhronosGroup/glTF#2137

[aaronfranke]

Where can I find example glTF files that use KHR_audio?