Description

Opus is free / open audio codec and is unmatched for interactive speech and music transmission over the Internet, but is also intended for storage and streaming applications. It is standardized by the Internet Engineering Task Force (IETF) as RFC 6716 which incorporated technology from Skype’s SILK codec and Xiph.Org’s CELT codec.

Original forum discussion.
Original PR: #1077
This PR is an adaptation of #1259 and superseded it.

On Windows I currently don't hear anything when running the sound example, haven't yet figured out why.

Building Opus and Opusfile with FetchContent brought new challenges:

• The header file don't live in a sub-directory in the source tree and thus opus/ can't be used as path prefix
• Opusfile does some weird version checking with git, which prevents us from using a shallow clone
• There are some warnings coming from macros and opus

Tasks

• Have CI pass
• Tested on Linux
• Tested on Windows
• Tested on macOS
• Tested on iOS
• Tested on Android

How to test this PR?

For playback run the sound example.
For writing, I'll provide an example later on.