// Plays a two-second sine wave using WASAPI (shared mode).

import 'dart:ffi';

import 'dart:math' as math;

import 'dart:typed_data';

import 'package:ffi/ffi.dart';

import 'package:win32/win32.dart';

const refTimesPerSecond = 10_000_000;

const double refTimesPerMillisecond = refTimesPerSecond / 1000;

/// Simple sine-wave PCM generator.

final class SineWaveSource {

SineWaveSource({

required int frequency,

required int sampleRate,

required this.channels,

required int durationSeconds,

}) : _samples = _generate(frequency, sampleRate, durationSeconds);

final int channels;

final Float32List _samples;

var _position = 0;

static Float32List _generate(

int frequency,

int sampleRate,

int durationSeconds,

) {

final totalSamples = sampleRate * durationSeconds;

final samples = Float32List(totalSamples);

final radiansPerSample = 2 * math.pi * frequency / sampleRate;

for (var i = 0; i < totalSamples; i++) {

samples[i] = math.sin(i * radiansPerSample);

}

return samples;

}

/// Writes interleaved samples into the output buffer.

///

/// Returns `false` when no data remains.

bool write(int frameCount, Pointer<BYTE> buffer) {

if (_position >= _samples.length) return false;

final out = buffer.cast<FLOAT>();

final totalSamples = frameCount * channels;

for (var i = 0; i < totalSamples; i += channels) {

final value = (_position < _samples.length) ? _samples[_position] : 0.0;

for (var ch = 0; ch < channels; ch++) {

out[i + ch] = value;

}

_position++;

}

return true;

}

}

/// High-level WASAPI renderer.

final class WasapiRenderer {

const WasapiRenderer(this._audioClient, this._renderClient);

final IAudioClient3 _audioClient;

final IAudioRenderClient _renderClient;

int get bufferFrames => _audioClient.getBufferSize();

void play(SineWaveSource source, WAVEFORMATEX format) {

final sampleRate = format.nSamplesPerSec;

final bufferDurationHns = refTimesPerSecond * bufferFrames ~/ sampleRate;

// Initial fill

var framesAvailable = bufferFrames;

var data = _renderClient.getBuffer(framesAvailable);

var hasData = source.write(framesAvailable, data);

_renderClient.releaseBuffer(

framesAvailable,

hasData ? 0 : AUDCLNT_BUFFERFLAGS_SILENT,

);

_audioClient.start();

while (hasData) {

Sleep(bufferDurationHns ~/ refTimesPerMillisecond ~/ 2);

final padding = _audioClient.getCurrentPadding();

framesAvailable = bufferFrames - padding;

if (framesAvailable == 0) continue;

data = _renderClient.getBuffer(framesAvailable);

hasData = source.write(framesAvailable, data);

_renderClient.releaseBuffer(

framesAvailable,

hasData ? 0 : AUDCLNT_BUFFERFLAGS_SILENT,

);

}

// Allow tail to drain

Sleep(bufferDurationHns ~/ refTimesPerMillisecond ~/ 2);

_audioClient.stop();

}

}

void main() {

CoInitializeEx(COINIT_MULTITHREADED);

using((arena) {

// Enumerate output devices

final enumerator = arena.com<IMMDeviceEnumerator>(MMDeviceEnumerator);

final devices = arena.adopt(

enumerator.enumAudioEndpoints(eRender, DEVICE_STATE_ACTIVE)!,

);

final count = devices.getCount();

print('$count audio output device(s) detected:\n');

final friendlyNameKey = arena<PROPERTYKEY>()

..ref = PKEY_DeviceInterface_FriendlyName;

for (var i = 0; i < count; i++) {

final device = arena.adopt(devices.item(i)!);

final pId = device.getId();

final id = pId.toDartString();

free(pId);

final props = arena.adopt(device.openPropertyStore(STGM_READ)!);

final value = PropVariant.fromPointer(props.getValue(friendlyNameKey));

final friendlyName = value.pwszVal.toDartString();

value.free();

print('ID: $id');

print('Name: $friendlyName\n');

}

// Default render device

final device = arena.adopt(

enumerator.getDefaultAudioEndpoint(eRender, eConsole)!,

);

final audioClient = arena.adopt(

device.activate<IAudioClient3>(CLSCTX_ALL, null),

);

final format = arena.using(audioClient.getMixFormat(), free);

audioClient.initialize(

AUDCLNT_SHAREMODE_SHARED,

0,

30_000, // 3 seconds in 100ns units

0,

format,

null,

);

final renderClient = arena.adopt(

audioClient.getService<IAudioRenderClient>(),

);

final WAVEFORMATEX(:nSamplesPerSec, :nChannels) = format.ref;

final source = SineWaveSource(

frequency: 440,

sampleRate: nSamplesPerSec,

channels: nChannels,

durationSeconds: 2,

);

WasapiRenderer(audioClient, renderClient).play(source, format.ref);

});

}