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iOS default sample rate pulled from audio unit
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@MichaelHills
MichaelHills committed Oct 24, 2020
1 parent ce7a2a0 commit 246568f
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Showing 2 changed files with 53 additions and 52 deletions.
4 changes: 2 additions & 2 deletions examples/ios-feedback/src/feedback.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -82,9 +82,9 @@ pub fn run_example() -> Result<(), anyhow::Error> {
"Attempting to build both streams with f32 samples and `{:?}`.",
config
);
println!("setup is");
println!("Setup input stream");
let input_stream = input_device.build_input_stream(&config, input_data_fn, err_fn)?;
println!("setup os");
println!("Setup output stream");
let output_stream = output_device.build_output_stream(&config, output_data_fn, err_fn)?;
println!("Successfully built streams.");

Expand Down
101 changes: 51 additions & 50 deletions src/host/coreaudio/ios/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,8 @@
//! the AVAudioSession objc API which doesn't exist on macOS.
//!
//! TODO:
//! - Use AVAudioSession to enumerate (and set) buffer size / sample rate / number of channels
//! - Use AVAudioSession to enumerate buffer size / sample rate / number of channels and set
//! buffer size.
//!

extern crate core_foundation_sys;
Expand Down Expand Up @@ -36,8 +37,6 @@ use std::slice;

pub mod enumerate;

const DEFAULT_SAMPLE_RATE: SampleRate = SampleRate(44_100);

// These days the default of iOS is now F32 and no longer I16
const SUPPORTED_SAMPLE_FORMAT: SampleFormat = SampleFormat::F32;

Expand Down Expand Up @@ -84,26 +83,15 @@ impl Device {
&self,
) -> Result<SupportedInputConfigs, SupportedStreamConfigsError> {
// TODO: query AVAudioSession for parameters, some values like sample rate and buffer size
// probably need to be tested but channels can be enumerated.

// setup an audio unit for recording, and then pull some default parameters off it

let mut audio_unit = create_audio_unit()?;
audio_unit.uninitialize()?;
configure_for_recording(&mut audio_unit)?;
audio_unit.initialize()?;

let id = kAudioUnitProperty_StreamFormat;
let asbd: AudioStreamBasicDescription =
audio_unit.get_property(id, Scope::Input, Element::Input)?;

let buffer_size = SupportedBufferSize::Range { min: 0, max: 0 };
// probably need to actually be set to see if it works, but channels can be enumerated.

let asbd: AudioStreamBasicDescription = default_input_asbd()?;
let stream_config = stream_config_from_asbd(asbd);
Ok(vec![SupportedStreamConfigRange {
channels: asbd.mChannelsPerFrame as u16,
min_sample_rate: SampleRate(asbd.mSampleRate as u32),
max_sample_rate: SampleRate(asbd.mSampleRate as u32),
buffer_size: buffer_size.clone(),
channels: stream_config.channels,
min_sample_rate: stream_config.sample_rate,
max_sample_rate: stream_config.sample_rate,
buffer_size: stream_config.buffer_size.clone(),
sample_format: SUPPORTED_SAMPLE_FORMAT,
}]
.into_iter())
Expand All @@ -114,22 +102,17 @@ impl Device {
&self,
) -> Result<SupportedOutputConfigs, SupportedStreamConfigsError> {
// TODO: query AVAudioSession for parameters, some values like sample rate and buffer size
// probably need to be tested but channels can be enumerated.
// probably need to actually be set to see if it works, but channels can be enumerated.

// setup an audio unit, and then pull some default parameters off it
let asbd: AudioStreamBasicDescription = default_output_asbd()?;
let stream_config = stream_config_from_asbd(asbd);

let audio_unit = create_audio_unit()?;
let id = kAudioUnitProperty_StreamFormat;
let asbd: AudioStreamBasicDescription =
audio_unit.get_property(id, Scope::Output, Element::Output)?;

let buffer_size = SupportedBufferSize::Range { min: 0, max: 0 };
let configs: Vec<_> = (1..=asbd.mChannelsPerFrame as u16)
.map(|channels| SupportedStreamConfigRange {
channels,
min_sample_rate: SampleRate(asbd.mSampleRate as u32),
max_sample_rate: SampleRate(asbd.mSampleRate as u32),
buffer_size: buffer_size.clone(),
min_sample_rate: stream_config.sample_rate,
max_sample_rate: stream_config.sample_rate,
buffer_size: stream_config.buffer_size.clone(),
sample_format: SUPPORTED_SAMPLE_FORMAT,
})
.collect();
Expand All @@ -138,28 +121,16 @@ impl Device {

#[inline]
fn default_input_config(&self) -> Result<SupportedStreamConfig, DefaultStreamConfigError> {
const EXPECT: &str = "expected at least one valid coreaudio stream config";
let config = self
.supported_input_configs()
.expect(EXPECT)
.max_by(|a, b| a.cmp_default_heuristics(b))
.unwrap()
.with_sample_rate(DEFAULT_SAMPLE_RATE);

Ok(config)
let asbd: AudioStreamBasicDescription = default_input_asbd()?;
let stream_config = stream_config_from_asbd(asbd);
Ok(stream_config)
}

#[inline]
fn default_output_config(&self) -> Result<SupportedStreamConfig, DefaultStreamConfigError> {
const EXPECT: &str = "expected at least one valid coreaudio stream config";
let config = self
.supported_output_configs()
.expect(EXPECT)
.max_by(|a, b| a.cmp_default_heuristics(b))
.unwrap()
.with_sample_rate(DEFAULT_SAMPLE_RATE);

Ok(config)
let asbd: AudioStreamBasicDescription = default_output_asbd()?;
let stream_config = stream_config_from_asbd(asbd);
Ok(stream_config)
}
}

Expand Down Expand Up @@ -428,3 +399,33 @@ fn configure_for_recording(audio_unit: &mut AudioUnit) -> Result<(), coreaudio::

Ok(())
}

fn default_output_asbd() -> Result<AudioStreamBasicDescription, coreaudio::Error> {
let mut audio_unit = create_audio_unit()?;
let id = kAudioUnitProperty_StreamFormat;
let asbd: AudioStreamBasicDescription =
audio_unit.get_property(id, Scope::Output, Element::Output)?;
Ok(asbd)
}

fn default_input_asbd() -> Result<AudioStreamBasicDescription, coreaudio::Error> {
let mut audio_unit = create_audio_unit()?;
audio_unit.uninitialize()?;
configure_for_recording(&mut audio_unit)?;
audio_unit.initialize()?;

let id = kAudioUnitProperty_StreamFormat;
let asbd: AudioStreamBasicDescription =
audio_unit.get_property(id, Scope::Input, Element::Input)?;
Ok(asbd)
}

fn stream_config_from_asbd(asbd: AudioStreamBasicDescription) -> SupportedStreamConfig {
let buffer_size = SupportedBufferSize::Range { min: 0, max: 0 };
SupportedStreamConfig {
channels: asbd.mChannelsPerFrame as u16,
sample_rate: SampleRate(asbd.mSampleRate as u32),
buffer_size: buffer_size.clone(),
sample_format: SUPPORTED_SAMPLE_FORMAT,
}
}

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