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{sysaudio,examples}: add support for multiple channels

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Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
This commit is contained in:
Stephen Gutekanst 2022-08-28 23:15:56 -07:00 • committed by Stephen Gutekanst
parent 587ea05d1e
commit 1dc3a4cba8
3 changed files with 82 additions and 52 deletions
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40
examples/sysaudio/main.zig
View file

@ -6,33 +6,33 @@ const js = mach.sysjs;
pub const App = @This();
audio: sysaudio,
device: sysaudio.Device,
device: *sysaudio.Device,
tone_engine: ToneEngine = .{},
pub fn init(app: *App, _: *mach.Core) !void {
pub fn init(app: *App, core: *mach.Core) !void {
const audio = try sysaudio.init();
errdefer audio.deinit();
const device = try audio.requestDevice(.{ .mode = .output, .channels = 1 });
errdefer device.deinit();
var device = try audio.requestDevice(core.allocator, .{ .mode = .output, .channels = 2 });
errdefer device.deinit(core.allocator);
device.setCallback(callback, app);
device.start();
try device.start();
app.audio = audio;
app.device = device;
}
fn callback(_: *sysaudio.Device, user_data: ?*anyopaque, buffer: []u8) void {
fn callback(device: *sysaudio.Device, user_data: ?*anyopaque, buffer: []u8) void {
// TODO(sysaudio): should make user_data pointer type-safe
const app: *App = @ptrCast(*App, @alignCast(@alignOf(App), user_data));
// Where the magic happens: fill our audio buffer with PCM dat.
app.tone_engine.render(buffer);
app.tone_engine.render(device.descriptor, buffer);
}
pub fn deinit(app: *App, _: *mach.Core) void {
app.device.deinit();
pub fn deinit(app: *App, core: *mach.Core) void {
app.device.deinit(core.allocator);
app.audio.deinit();
}
@ -40,13 +40,12 @@ pub fn update(app: *App, engine: *mach.Core) !void {
while (engine.pollEvent()) |event| {
switch (event) {
.key_press => |ev| {
app.device.start();
try app.device.start();
app.tone_engine.play(ToneEngine.keyToFrequency(ev.key));
},
else => {},
}
}
app.audio.waitEvents();
}
// A simple tone engine.
@ -70,15 +69,16 @@ pub const ToneEngine = struct {
duration: usize,
};
pub fn render(engine: *ToneEngine, buffer: []u8) void {
pub fn render(engine: *ToneEngine, descriptor: sysaudio.DeviceDescriptor, buffer: []u8) void {
// TODO(sysaudio): demonstrate how to properly handle format of the buffer here.
// Right now we blindly assume f32 format, which is wrong (but always right in WASM.)
//
// TODO(sysaudio): get sample rate from callback, don't hard-code it here.
const sample_rate = 44100.0;
const sample_rate = @intToFloat(f32, descriptor.sample_rate.?);
const buf = @ptrCast([*]f32, @alignCast(@alignOf(f32), buffer.ptr))[0 .. buffer.len / @sizeOf(f32)];
const frames = buf.len / descriptor.channels.?;
for (buf) |_, i| {
var frame: usize = 0;
while (frame < frames) : (frame += 1) {
// Render the sample for this frame (e.g. for both left and right audio channels.)
var sample: f32 = 0;
for (engine.playing) |*tone| {
if (tone.sample_counter >= tone.duration) {
@ -104,11 +104,17 @@ pub const ToneEngine = struct {
sample += sine_wave * fade_in * fade_out;
}
buf[i] = sample;
// Emit the sample on all channels.
var channel: usize = 0;
while (channel < descriptor.channels.?) : (channel += 1) {
var channel_buf = buf[channel * frames .. (channel + 1) * frames];
channel_buf[frame] = sample;
}
}
}
pub fn play(engine: *ToneEngine, frequency: f32) void {
// TODO(sysaudio): get from device
const sample_rate = 44100.0;
for (engine.playing) |*tone| {

4
libs/sysaudio/src/main.zig
View file

@ -55,8 +55,8 @@ pub fn waitEvents(self: Audio) void {
self.backend.waitEvents();
}
pub fn requestDevice(self: Audio, config: DeviceDescriptor) Error!Device {
return self.backend.requestDevice(config);
pub fn requestDevice(self: Audio, allocator: std.mem.Allocator, config: DeviceDescriptor) Error!*Device {
return self.backend.requestDevice(allocator, config);
}
pub fn inputDeviceIterator(self: Audio) DeviceIterator {

90
libs/sysaudio/src/webaudio.zig
View file

@ -11,24 +11,28 @@ else
*const fn (device: *Device, user_data: ?*anyopaque, buffer: []u8) void;
pub const Device = struct {
descriptor: DeviceDescriptor,
// Internal fields.
context: js.Object,
pub fn deinit(device: Device) void {
pub fn deinit(device: *Device, allocator: std.mem.Allocator) void {
device.context.deinit();
allocator.destroy(device);
}
pub fn setCallback(device: Device, callback: DataCallback, user_data: ?*anyopaque) void {
device.context.set("device", js.createNumber(@intToFloat(f64, @ptrToInt(&device))));
pub fn setCallback(device: *Device, callback: DataCallback, user_data: ?*anyopaque) void {
device.context.set("device", js.createNumber(@intToFloat(f64, @ptrToInt(device))));
device.context.set("callback", js.createNumber(@intToFloat(f64, @ptrToInt(callback))));
if (user_data) |ud|
device.context.set("user_data", js.createNumber(@intToFloat(f64, @ptrToInt(ud))));
}
pub fn pause(device: Device) void {
pub fn pause(device: *Device) Error!void {
_ = device.context.call("suspend", &.{});
}
pub fn start(device: Device) void {
pub fn start(device: *Device) Error!void {
_ = device.context.call("resume", &.{});
}
};
@ -45,6 +49,7 @@ pub const DeviceIterator = struct {
pub const IteratorError = error{};
pub const Error = error{
OutOfMemory,
AudioUnsupported,
};
@ -62,13 +67,14 @@ pub fn deinit(audio: Audio) void {
audio.context_constructor.deinit();
}
// TODO)sysaudio): implement waitEvents for WebAudio, will a WASM process terminate without this?
pub fn waitEvents(_: Audio) void {}
const default_channel_count = 2;
const default_sample_rate = 48000;
const default_buffer_size = 1024; // 21.33ms
const default_buffer_size_per_channel = 1024; // 21.33ms
pub fn requestDevice(audio: Audio, config: DeviceDescriptor) Error!Device {
pub fn requestDevice(audio: Audio, allocator: std.mem.Allocator, config: DeviceDescriptor) Error!*Device {
// NOTE: WebAudio only supports F32 audio format, so config.format is unused
const mode = config.mode orelse .output;
const channels = config.channels orelse default_channel_count;
@ -84,7 +90,7 @@ pub fn requestDevice(audio: Audio, config: DeviceDescriptor) Error!Device {
const input_channels = if (mode == .input) js.createNumber(@intToFloat(f64, channels)) else js.createUndefined();
const output_channels = if (mode == .output) js.createNumber(@intToFloat(f64, channels)) else js.createUndefined();
const node = context.call("createScriptProcessor", &.{ js.createNumber(default_buffer_size), input_channels, output_channels }).view(.object);
const node = context.call("createScriptProcessor", &.{ js.createNumber(default_buffer_size_per_channel), input_channels, output_channels }).view(.object);
defer node.deinit();
context.set("node", node.toValue());
@ -107,7 +113,18 @@ pub fn requestDevice(audio: Audio, config: DeviceDescriptor) Error!Device {
_ = node.call("connect", &.{destination.toValue()});
}
return Device{ .context = context };
// TODO(sysaudio): introduce a descriptor type that has non-optional fields.
var descriptor = config;
descriptor.mode = descriptor.mode orelse .output;
descriptor.channels = descriptor.channels orelse default_channel_count;
descriptor.sample_rate = descriptor.sample_rate orelse default_sample_rate;
const device = try allocator.create(Device);
device.* = .{
.descriptor = descriptor,
.context = context,
};
return device;
}
fn audioProcessEvent(args: js.Object, _: usize, captures: []js.Value) js.Value {
@ -117,42 +134,49 @@ fn audioProcessEvent(args: js.Object, _: usize, captures: []js.Value) js.Value {
defer audio_event.deinit();
const output_buffer = audio_event.get("outputBuffer").view(.object);
defer output_buffer.deinit();
const num_channels = @floatToInt(usize, output_buffer.get("numberOfChannels").view(.num));
const buffer_length = default_buffer_size * @sizeOf(f32);
var buffer: [buffer_length]u8 = undefined;
const buffer_length = default_buffer_size_per_channel * num_channels * @sizeOf(f32);
// TODO(sysaudio): reuse buffer, do not allocate in this hot path
const buffer = std.heap.page_allocator.alloc(u8, buffer_length) catch unreachable;
defer std.heap.page_allocator.free(buffer);
const callback = device_context.get("callback");
if (!callback.is(.undef)) {
// Do not deinit, we are not making a new device, just creating a view to the current one.
var dev = Device{ .context = device_context };
var dev = @intToPtr(*Device, @floatToInt(usize, device_context.get("device").view(.num)));
const cb = @intToPtr(DataCallback, @floatToInt(usize, callback.view(.num)));
const user_data = device_context.get("user_data");
const ud = if (user_data.is(.undef)) null else @intToPtr(*anyopaque, @floatToInt(usize, user_data.view(.num)));
// TODO(sysaudio): do not reconstruct Uint8Array (expensive)
const source = js.constructType("Uint8Array", &.{js.createNumber(@intToFloat(f64, buffer_length))});
defer source.deinit();
cb(dev, ud, buffer[0..]);
source.copyBytes(buffer[0..]);
const float_source = js.constructType("Float32Array", &.{
source.get("buffer"),
source.get("byteOffset"),
js.createNumber(source.get("byteLength").view(.num) / 4),
});
defer float_source.deinit();
js.global().set("source", source.toValue());
js.global().set("float_source", float_source.toValue());
js.global().set("output_buffer", output_buffer.toValue());
var channel: usize = 0;
while (channel < @floatToInt(usize, output_buffer.get("numberOfChannels").view(.num))) : (channel += 1) {
const source = js.constructType("Uint8Array", &.{js.createNumber(buffer_length)});
defer source.deinit();
cb(&dev, ud, buffer[0..]);
source.copyBytes(buffer[0..]);
const float_source = js.constructType("Float32Array", &.{
source.get("buffer"),
source.get("byteOffset"),
js.createNumber(source.get("byteLength").view(.num) / 4),
});
defer float_source.deinit();
js.global().set("source", source.toValue());
js.global().set("float_source", float_source.toValue());
js.global().set("output_buffer", output_buffer.toValue());
// TODO: investigate if using copyToChannel would be better?
while (channel < num_channels) : (channel += 1) {
// TODO(sysaudio): investigate if using copyToChannel would be better?
//_ = output_buffer.call("copyToChannel", &.{ float_source.toValue(), js.createNumber(@intToFloat(f64, channel)) });
const output_data = output_buffer.call("getChannelData", &.{js.createNumber(@intToFloat(f64, channel))}).view(.object);
defer output_data.deinit();
_ = output_data.call("set", &.{float_source.toValue()});
const channel_slice = float_source.call("slice", &.{
js.createNumber(@intToFloat(f64, channel * default_buffer_size_per_channel)),
js.createNumber(@intToFloat(f64, (channel + 1) * default_buffer_size_per_channel)),
});
_ = output_data.call("set", &.{channel_slice});
}
}