[macOS] Fixed SupportedStreamConfigRange returns same min_samplerate and max_samplerate

[tomoyanonymous]

On MacOS, Device::supported_output/input_configs returns multiple configs and they are the same values except for min_samplerate and max_samplerate. However, the pair of samplerates are always the same value like min_samplerate:44100, max_samplerate:44100 and min_samplerate:48000, max_samplerate:48000.

With this PR, Device::supported_output/input_configs now returns a combined SupportedStreamConfig. I found this problem when I tried to reorder the available streamconfigs depending on the parameter in my application.

On MacOS, Device::default_input/output_config does not use cmp_default_heuristics (I guess wasapi&asio are the same), but I hope this could be used in every platform ideally (though this PR does not address the implementation of the default config-related method).

Tested on: M1 Macbook Air(2020), macOS 15.0.1

[roderickvd]

Thanks for your (much) earlier contribution. We're breathing new life into cpal and we're going through the backlog.

[roderickvd]

Thanks for the quick update after all this time! I like the approach.

Going into a further review, I solicited some feedback from Copilot if you want to take a look if any of that makes sense.

It you would also include an entry in the changelog?

[tomoyanonymous]

rebased the branch on recent master to resolve conflict in changelog.

[Copilot]

Pull Request Overview

This PR fixes an issue on macOS where Device::supported_output/input_configs was returning redundant configuration entries with identical min/max sample rates. The change consolidates these duplicate entries into a single configuration that spans the full available sample rate range.

• Adds logic to detect when all sample rate ranges have identical min/max values
• Returns a single consolidated config when all ranges are identical, or individual ranges when they differ
• Updates changelog to document the behavior change

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/host/coreaudio/macos/mod.rs	Implements the consolidation logic for sample rate ranges and adds explanatory comments
CHANGELOG.md	Documents the new behavior for CoreAudio's supported_configs method

[roderickvd]

enumerate example output before:

Supported hosts:
  [CoreAudio]
Available hosts:
  [CoreAudio]
CoreAudio
  Default Input Device:
    Some("MacBook Air Microphone")
  Default Output Device:
    Some("MacBook Air Speakers")
  Devices: 
  1. "MacBook Air Microphone"
    Default input stream config:
      SupportedStreamConfig { channels: 1, sample_rate: SampleRate(44100), buffer_size: Range { min: 14, max: 4096 }, sample_format: F32 }
    All supported input stream configs:
      1.1. SupportedStreamConfigRange { channels: 1, min_sample_rate: SampleRate(44100), max_sample_rate: SampleRate(44100), buffer_size: Range { min: 14, max: 4096 }, sample_format: F32 }
      1.2. SupportedStreamConfigRange { channels: 1, min_sample_rate: SampleRate(48000), max_sample_rate: SampleRate(48000), buffer_size: Range { min: 14, max: 4096 }, sample_format: F32 }
      1.3. SupportedStreamConfigRange { channels: 1, min_sample_rate: SampleRate(88200), max_sample_rate: SampleRate(88200), buffer_size: Range { min: 14, max: 4096 }, sample_format: F32 }
      1.4. SupportedStreamConfigRange { channels: 1, min_sample_rate: SampleRate(96000), max_sample_rate: SampleRate(96000), buffer_size: Range { min: 14, max: 4096 }, sample_format: F32 }
  2. "MacBook Air Speakers"
    Default output stream config:
      SupportedStreamConfig { channels: 2, sample_rate: SampleRate(96000), buffer_size: Range { min: 29, max: 4096 }, sample_format: F32 }
    All supported output stream configs:
      2.1. SupportedStreamConfigRange { channels: 2, min_sample_rate: SampleRate(44100), max_sample_rate: SampleRate(44100), buffer_size: Range { min: 29, max: 4096 }, sample_format: F32 }
      2.2. SupportedStreamConfigRange { channels: 2, min_sample_rate: SampleRate(48000), max_sample_rate: SampleRate(48000), buffer_size: Range { min: 29, max: 4096 }, sample_format: F32 }
      2.3. SupportedStreamConfigRange { channels: 2, min_sample_rate: SampleRate(88200), max_sample_rate: SampleRate(88200), buffer_size: Range { min: 29, max: 4096 }, sample_format: F32 }
      2.4. SupportedStreamConfigRange { channels: 2, min_sample_rate: SampleRate(96000), max_sample_rate: SampleRate(96000), buffer_size: Range { min: 29, max: 4096 }, sample_format: F32 }
  3. "Microsoft Teams Audio"
    Default input stream config:
      SupportedStreamConfig { channels: 1, sample_rate: SampleRate(48000), buffer_size: Range { min: 15, max: 4096 }, sample_format: F32 }
    All supported input stream configs:
      3.1. SupportedStreamConfigRange { channels: 1, min_sample_rate: SampleRate(48000), max_sample_rate: SampleRate(48000), buffer_size: Range { min: 15, max: 4096 }, sample_format: F32 }
    Default output stream config:
      SupportedStreamConfig { channels: 1, sample_rate: SampleRate(48000), buffer_size: Range { min: 15, max: 4096 }, sample_format: F32 }
    All supported output stream configs:
      3.1. SupportedStreamConfigRange { channels: 1, min_sample_rate: SampleRate(48000), max_sample_rate: SampleRate(48000), buffer_size: Range { min: 15, max: 4096 }, sample_format: F32 }

enumerate example output with this PR:

Supported hosts:
  [CoreAudio]
Available hosts:
  [CoreAudio]
CoreAudio
  Default Input Device:
    Some("MacBook Air Microphone")
  Default Output Device:
    Some("MacBook Air Speakers")
  Devices: 
  1. "MacBook Air Microphone"
    Default input stream config:
      SupportedStreamConfig { channels: 1, sample_rate: SampleRate(44100), buffer_size: Range { min: 14, max: 4096 }, sample_format: F32 }
    All supported input stream configs:
      1.1. SupportedStreamConfigRange { channels: 1, min_sample_rate: SampleRate(44100), max_sample_rate: SampleRate(96000), buffer_size: Range { min: 14, max: 4096 }, sample_format: F32 }
  2. "MacBook Air Speakers"
    Default output stream config:
      SupportedStreamConfig { channels: 2, sample_rate: SampleRate(96000), buffer_size: Range { min: 29, max: 4096 }, sample_format: F32 }
    All supported output stream configs:
      2.1. SupportedStreamConfigRange { channels: 2, min_sample_rate: SampleRate(44100), max_sample_rate: SampleRate(96000), buffer_size: Range { min: 29, max: 4096 }, sample_format: F32 }
  3. "Microsoft Teams Audio"
    Default input stream config:
      SupportedStreamConfig { channels: 1, sample_rate: SampleRate(48000), buffer_size: Range { min: 15, max: 4096 }, sample_format: F32 }
    All supported input stream configs:
      3.1. SupportedStreamConfigRange { channels: 1, min_sample_rate: SampleRate(48000), max_sample_rate: SampleRate(48000), buffer_size: Range { min: 15, max: 4096 }, sample_format: F32 }
    Default output stream config:
      SupportedStreamConfig { channels: 1, sample_rate: SampleRate(48000), buffer_size: Range { min: 15, max: 4096 }, sample_format: F32 }
    All supported output stream configs:
      3.1. SupportedStreamConfigRange { channels: 1, min_sample_rate: SampleRate(48000), max_sample_rate: SampleRate(48000), buffer_size: Range { min: 15, max: 4096 }, sample_format: F32 }

LGTM! I'm gonna help you out with these into_iter / iter calls - I see you've granted write access - and am going to merge this.

Thanks a lot, this is a good enhancement to also consider for the other hosts.