[macOS] AudioUnitRender errors with -10863 when changing to non-default audio input device

[xubiod]

Tested versions

Reproduced in:

• v4.4.1.stable.official [49a5bc7]
  • Obtained from Steam
• v4.5.dev.custom_build [09fcbb8]
• v4.4.stable.official [4c311cb]
• v4.3.stable.official [77dcf97]

System information

Godot v4.5.dev (09fcbb8) - macOS Sequoia (15.5.0) - Multi-window, 1 monitor - Metal (Forward+) - integrated Apple M2 (Apple8) - Apple M2 (8 threads)

Issue description

Swapping the audio input device to one that is not the default causes a AudioUnitRender failure with code -10863. This is spammed into the output.

ERROR: AudioUnitRender failed, code: -10863
   at: input_callback (drivers/coreaudio/audio_driver_coreaudio.mm:260)

This first came to my attention when trying to use my iPhone as an audio input with Continuity, but also happens with wireless earbuds with a microphone.

Doing some research about macOS audio input with Godot lead to #88628, so if I had to label a suspect it would seem to be a mix rate conflict.

Steps to reproduce

1. Enable audio input for the project
2. Create an AudioStreamMicrophone on any AudioStreamPlayer kind of node.
3. Have the AudioStreamPlayer start playing with the microphone stream
4. Change the audio input device from the default device to another device

Minimal reproduction project (MRP)

The following project also has a label reading the input from a SpectrumAnalyze to get in-game feedback.

audio_input_test_on_source_2025-05-14_09-35-38.zip