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Initial work on audio while airbourne.

This commit is contained in:
Luke Curley 2023-04-01 19:04:08 +09:00
parent 0240af66cd
commit 032c49ab50
12 changed files with 376 additions and 66 deletions
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65
player/src/audio/decoder.ts
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@ -1,10 +1,13 @@
import * as Message from "./message";
import { InitParser } from "../mp4/init";
import * as MP4 from "../mp4"
import * as Stream from "../stream"
import * as Util from "../util"
import { Renderer } from "./renderer"
import { MP4New, MP4Sample, MP4ArrayBuffer } from "../mp4/index"
export class Decoder {
tracks: Map<string, InitParser>;
// Store the init message for each track
tracks: Map<string, Util.Deferred<Message.Init>>
renderer: Renderer;
constructor(renderer: Renderer) {
@ -15,41 +18,32 @@ export class Decoder {
async init(msg: Message.Init) {
let track = this.tracks.get(msg.track);
if (!track) {
track = new InitParser()
track = new Util.Deferred()
this.tracks.set(msg.track, track)
}
while (1) {
const data = await msg.stream.read()
if (!data) break
track.init(data)
if (msg.info.audioTracks.length != 1 || msg.info.videoTracks.length != 0) {
throw new Error("Expected a single audio track")
}
// TODO this will hang on incomplete data
const init = await track.ready;
const info = init.info;
if (info.audioTracks.length != 1 || info.videoTracks.length != 0) {
throw new Error("expected a single audio track")
}
track.resolve(msg)
}
async decode(msg: Message.Segment) {
let track = this.tracks.get(msg.track);
if (!track) {
track = new InitParser()
track = new Util.Deferred()
this.tracks.set(msg.track, track)
}
// Wait for the init segment to be fully received and parsed
const init = await track.ready;
const init = await track.promise;
const info = init.info;
const video = info.videoTracks[0]
const audio = info.audioTracks[0]
const decoder = new AudioDecoder({
output: (frame: AudioFrame) => {
this.renderer.push(frame)
this.renderer.emit(frame)
},
error: (err: Error) => {
console.warn(err)
@ -57,21 +51,19 @@ export class Decoder {
});
decoder.configure({
codec: info.mime,
// TODO what else?
codec: audio.codec,
// optimizeForLatency: true
})
const input = MP4New();
const input = MP4.New();
input.onSamples = (id: number, user: any, samples: MP4Sample[]) => {
input.onSamples = (id: number, user: any, samples: MP4.Sample[]) => {
for (let sample of samples) {
const timestamp = sample.dts / (1000 / info.timescale) // milliseconds
// TODO this assumes that timescale == sample rate
decoder.decode(new EncodedAudioChunk({
data: sample.data,
duration: sample.duration,
timestamp: timestamp,
timestamp: sample.dts,
}))
}
}
@ -81,13 +73,16 @@ export class Decoder {
input.start();
}
let offset = 0
// MP4box requires us to reparse the init segment unfortunately
for (let raw of track.raw) {
offset = input.appendBuffer(raw)
let offset = 0;
for (let raw of init.raw) {
raw.fileStart = offset
input.appendBuffer(raw)
}
const stream = new Stream.Reader(msg.reader, msg.buffer)
/* TODO I'm not actually sure why this code doesn't work; something trips up the MP4 parser
while (1) {
const data = await stream.read()
@ -99,17 +94,17 @@ export class Decoder {
*/
// One day I'll figure it out; until then read one top-level atom at a time
while (!await msg.stream.done()) {
const raw = await msg.stream.peek(4)
while (!await stream.done()) {
const raw = await stream.peek(4)
const size = new DataView(raw.buffer, raw.byteOffset, raw.byteLength).getUint32(0)
const atom = await msg.stream.bytes(size)
const atom = await stream.bytes(size)
// Make a copy of the atom because mp4box only accepts an ArrayBuffer unfortunately
let box = new Uint8Array(atom.byteLength);
box.set(atom)
// and for some reason we need to modify the underlying ArrayBuffer with offset
let buffer = box.buffer as MP4ArrayBuffer
let buffer = box.buffer as MP4.ArrayBufferOffset
buffer.fileStart = offset
// Parse the data

6
player/src/audio/index.ts
View File

@ -6,14 +6,14 @@ export default class Audio {
constructor(config: Message.Config) {
this.worker = new Worker(new URL('worker.ts', import.meta.url), { type: "module" })
this.worker.postMessage({ config }, [ ])
this.worker.postMessage({ config }, [])
}
init(init: Message.Init) {
this.worker.postMessage({ init }, [ init.stream.buffer, init.stream.reader ])
this.worker.postMessage({ init }) // note: we copy the raw init bytes each time
}
segment(segment: Message.Segment) {
this.worker.postMessage({ segment }, [ segment.stream.buffer, segment.stream.reader ])
this.worker.postMessage({ segment }, [ segment.buffer.buffer, segment.reader ])
}
}

10
player/src/audio/message.ts
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@ -1,15 +1,17 @@
import Reader from "../stream/reader";
import * as MP4 from "../mp4"
export interface Config {
canvas: OffscreenCanvas;
// temporarily empty
}
export interface Init {
track: string;
stream: Reader;
info: MP4.Info;
raw: MP4.ArrayBufferOffset[];
}
export interface Segment {
track: string;
stream: Reader;
buffer: Uint8Array; // unread buffered data
reader: ReadableStream; // unread unbuffered data
}

20
player/src/audio/renderer.ts
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@ -1,12 +1,26 @@
import * as Message from "./message";
import Source from "./source";
export class Renderer {
ctx: AudioContext;
source: Source;
render: number; // non-zero if requestAnimationFrame has been called
sync: DOMHighResTimeStamp; // the wall clock value for timestamp 0
last?: number; // the timestamp of the last rendered frame
constructor(config: Message.Config) {
maxDuration: number; // the maximum duration allowed in the buffer
constructor() {
this.render = 0;
this.sync = 0;
this.maxDuration = 10 * 1000
// TODO evaluate { latencyHint: "interactive" }
this.ctx = new AudioContext()
this.source = new Source(this.ctx)
}
emit(frame: AudioFrame) {
this.source.emit(frame)
}
}

64
player/src/audio/source/index.ts Normal file
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@ -0,0 +1,64 @@
import * as Message from "./message"
import Ring from "./ring"
// Wrapper around the AudioWorklet API to make it easier to use.
export default class Source {
ctx: AudioContext;
worklet?: AudioWorkletNode; // async initialization
channels: Ring[];
ready: Promise<void>;
constructor(ctx: AudioContext) {
this.ctx = ctx
// two channels, holding a maximum of 1s at 44khz
this.channels = [
new Ring(44000),
new Ring(44000),
]
// Start loading the worklet
this.ready = this.setup()
}
private async setup(): Promise<void> {
// Load the worklet source code.
await this.ctx.audioWorklet.addModule('worklet.ts')
// Create a worklet
this.worklet = new AudioWorkletNode(this.ctx, 'source');
this.worklet.port.onmessage = this.onMessage.bind(this)
this.worklet.onprocessorerror = (e: Event) => {
console.error("Audio worklet error:", e);
};
const config: Message.Config = {
channels: this.channels,
}
this.worklet.port.postMessage({ config })
}
private async onMessage(e: MessageEvent) {
if (e.data.configReply) {
const reply = e.data.configReply as Message.ConfigReply
if (reply.error) {
throw reply.error
}
// Start playback
this.worklet?.connect(this.ctx.destination);
}
}
emit(frame: AudioFrame) {
for (let i = 0; i < frame.channels; i += 1) {
const ring = this.channels[i]
ring.set(frame, i)
}
}
}

11
player/src/audio/source/message.ts Normal file
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@ -0,0 +1,11 @@
import Ring from "./ring"
// Sent to the worklet to share ring buffers.
export interface Config {
channels: Ring[];
}
// Reply from the worklet indicating when the configuration was suscessful.
export interface ConfigReply {
error?: Error;
}

131
player/src/audio/source/ring.ts Normal file
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@ -0,0 +1,131 @@
// Ring buffer with audio samples.
// TODO typescript enums when I have internet access
const STATE = {
START: 0,
END: 1,
}
export default class Ring {
state: SharedArrayBuffer;
stateView: Int32Array;
buffer: SharedArrayBuffer;
capacity: number;
constructor(samples: number) {
this.state = new SharedArrayBuffer(Object.keys(STATE).length * Int32Array.BYTES_PER_ELEMENT)
this.stateView = new Int32Array(this.state)
this.setStart(0)
this.setEnd(0)
this.capacity = samples;
// TODO better way to loop in modern Javascript?
this.buffer = new SharedArrayBuffer(samples * Float32Array.BYTES_PER_ELEMENT)
}
setStart(start: number) {
return Atomics.store(this.stateView, STATE.START, start);
}
getStart(): number {
return Atomics.load(this.stateView, STATE.START);
}
setEnd(end: number) {
return Atomics.store(this.stateView, STATE.START, end);
}
getEnd(): number {
return Atomics.load(this.stateView, STATE.END);
}
set(frame: AudioFrame, channel: number) {
let start = this.getStart()
// The number of samples to skip at the start.
let offset = start - frame.timestamp;
if (offset > 0) {
console.warn("dropping old samples", offset)
} else {
offset = 0
}
let count = frame.numberOfFrames - offset;
if (count <= 0) {
frame.close()
// Skip the entire frame
return
}
if (start + this.capacity < frame.timestamp + count) {
// The renderer has to buffer frames; we have a fixed capacity.
// TODO maybe it's better to buffer here instead.
throw new Error("exceeded capacity")
}
let end = this.getEnd()
const startIndex = start % this.capacity;
const endIndex = end % this.capacity;
if (startIndex < endIndex) {
// One continuous range to copy.
const full = new Float32Array(this.buffer, startIndex, endIndex-startIndex)
frame.copyTo(full, {
planeIndex: channel,
frameOffset: offset,
frameCount: count,
})
} else {
// Wrapped around the ring buffer, so we have to copy twice.
const wrap = this.capacity - startIndex;
const first = new Float32Array(this.buffer, startIndex)
const second = new Float32Array(this.buffer, 0, endIndex)
frame.copyTo(first, {
planeIndex: channel,
frameOffset: offset,
frameCount: wrap,
})
frame.copyTo(second, {
planeIndex: channel,
frameOffset: offset + wrap,
frameCount: endIndex,
})
}
// TODO insert silence when index > end
if (frame.timestamp + count > end) {
end = frame.timestamp + count
this.setEnd(end)
}
}
peek(count: number): Float32Array[] {
const start = this.getStart()
const end = this.getEnd()
const startIndex = start % this.capacity;
const endIndex = end % this.capacity;
if (startIndex < endIndex) {
const full = new Float32Array(this.buffer, startIndex, endIndex - startIndex)
return [ full ]
} else {
const first = new Float32Array(this.buffer, startIndex)
const second = new Float32Array(this.buffer, 0, endIndex)
return [ first, second ]
}
}
advance(count: number) {
this.setStart(this.getStart() + count)
}
}

68
player/src/audio/source/worklet.ts Normal file
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@ -0,0 +1,68 @@
// This is an AudioWorklet that acts as a media source.
// The renderer copies audio samples to a ring buffer read by this worklet.
// The worklet then outputs those samples to emit audio.
import * as Message from "../message"
import * as Util from "../../util"
import Ring from "./ring"
class Source extends AudioWorkletProcessor {
channels?: Ring[];
constructor() {
// The super constructor call is required.
super();
this.port.onmessage = (e: MessageEvent) => {
if (e.data.config) {
this.config(e.data.config as Message.Config)
}
}
}
static get parameterDescriptors() {
return [];
}
config(config: Message.Config) {
this.channels = config.channels;
}
// TODO correct types
process(inputs: any, outputs: any, parameters: any) {
if (!this.channels) {
return
}
if (outputs.length != 1) {
throw new Error("only a single track is supported")
}
const track = outputs[0];
for (let i = 0; i < track.length; i += 1) {
const input = this.channels[i]
const output = track[i];
const parts = input.peek(output.length)
let offset = 0
for (let i = 0; i < parts.length; i += 1) {
output.set(parts[i], offset)
offset += parts[i].length
}
if (offset < output.length) {
// TODO render silence
}
// Always advance the full amount.
input.advance(output.length)
}
return true;
}
}
self.registerProcessor("source", Source);

12
player/src/audio/worker.ts
View File

@ -2,20 +2,24 @@ import { Renderer } from "./renderer"
import { Decoder } from "./decoder"
import * as Message from "./message"
let decoder: Decoder;
let renderer: Renderer;
let decoder: Decoder;
self.addEventListener('message', async (e: MessageEvent) => {
if (e.data.config) {
const config = e.data.config as Message.Config
const config = e.data.config as Message.Config;
renderer = new Renderer(config)
renderer = new Renderer()
decoder = new Decoder(renderer)
}
if (e.data.init) {
const init = e.data.init as Message.Init
await decoder.init(init)
}
if (e.data.segment) {
const segment = e.data.segment as Message.Segment
await decoder.decode(segment)
}
})

31
player/src/transport/index.ts
View File

@ -2,7 +2,8 @@ import * as Message from "./message"
import * as Stream from "../stream"
import * as MP4 from "../mp4"
import Video from "../video/index"
import Audio from "../audio"
import Video from "../video"
// @ts-ignore bundler embeds data
import fingerprint from 'bundle-text:./fingerprint.hex';
@ -19,13 +20,14 @@ export class Player {
api: Promise<WritableStream>;
tracks: Map<string, MP4.InitParser>
//audio: Worker;
audio: Audio;
video: Video;
constructor(props: PlayerInit) {
this.tracks = new Map();
//this.audio = new Worker("../audio")
// TODO move these to another class so this only deals with the transport.
this.audio = new Audio({})
this.video = new Video({
canvas: props.canvas.transferControlToOffscreen(),
})
@ -131,12 +133,20 @@ export class Player {
throw new Error("expected a single track")
}
if (info.videoTracks.length) {
if (info.audioTracks) {
this.audio.init({
track: msg.id,
info: info,
raw: track.raw,
})
} else if (info.videoTracks) {
this.video.init({
track: msg.id,
info: info,
raw: track.raw,
})
} else {
throw new Error("init is neither audio nor video")
}
}
@ -147,16 +157,23 @@ export class Player {
this.tracks.set(msg.init, track)
}
// Wait until we learn if this is an audio or video track
const info = await track.info
// Wait until we learn if this is an audio or video track
if (info.videoTracks.length) {
if (info.audioTracks) {
this.audio.segment({
track: msg.init,
buffer: stream.buffer,
reader: stream.reader,
})
} else if (info.videoTracks) {
this.video.segment({
track: msg.init,
buffer: stream.buffer,
reader: stream.reader,
})
} else {
throw new Error("segment is neither audio nor video")
}
}
}

6
player/src/video/decoder.ts
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@ -22,6 +22,10 @@ export class Decoder {
this.tracks.set(msg.track, track)
}
if (msg.info.videoTracks.length != 1 || msg.info.audioTracks.length != 0) {
throw new Error("Expected a single video track")
}
track.resolve(msg)
}
@ -39,7 +43,7 @@ export class Decoder {
const decoder = new VideoDecoder({
output: (frame: VideoFrame) => {
this.renderer.push(frame)
this.renderer.emit(frame)
},
error: (err: Error) => {
console.warn(err)

2
player/src/video/renderer.ts
View File

@ -17,7 +17,7 @@ export class Renderer {
this.maxDuration = 10 * 1000
}
push(frame: VideoFrame) {
emit(frame: VideoFrame) {
if (!this.sync) {
// Save the frame as the sync point
this.sync = performance.now() - frame.timestamp