mirror of
https://github.com/arcodange-org/mediabunny.git
synced 2026-09-30 12:23:52 +02:00
Create @mediabunny/mp3-encoder, restructure and extend build system
This commit is contained in:
Vanilagy
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/*!
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* Copyright (c) 2025-present, Vanilagy and contributors
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/.
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*/
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import createModule from '../build/lame';
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import type { WorkerCommand, WorkerResponse, WorkerResponseData } from './shared';
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type ExtendedEmscriptenModule = EmscriptenModule & {
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cwrap: typeof cwrap;
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};
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let module: ExtendedEmscriptenModule;
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let lamePtr: number;
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let storedNumberOfChannels: number;
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let storedSampleRate: number;
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let storedBitrate: number;
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let needsReset = false;
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let initLame: (
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numberOfChannels: number,
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sampleRate: number,
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bitrate: number
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) => number;
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let encodeSamples: (
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lame: number,
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leftPtr: number,
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rightPtr: number,
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sampleCount: number,
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outputPtr: number,
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outputSize: number
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) => number;
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let flushLame: (lame: number, outputPtr: number, outputSize: number) => number;
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let closeLame: (lame: number) => void;
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let inputSlice: Slice | null = null;
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let outputSlice: Slice | null = null;
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const init = async (numberOfChannels: number, sampleRate: number, bitrate: number) => {
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storedNumberOfChannels = numberOfChannels;
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storedSampleRate = sampleRate;
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storedBitrate = bitrate;
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module = (await createModule()) as ExtendedEmscriptenModule;
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// Set up the functions
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initLame = module.cwrap('init_lame', 'number', ['number', 'number', 'number']);
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encodeSamples = module.cwrap(
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'encode_samples',
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'number',
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['number', 'number', 'number', 'number', 'number', 'number'],
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);
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flushLame = module.cwrap('flush_lame', 'number', ['number', 'number', 'number']);
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closeLame = module.cwrap('close_lame', null, ['number']);
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lamePtr = initLame(numberOfChannels, sampleRate, bitrate);
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};
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const reset = () => {
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closeLame(lamePtr);
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lamePtr = initLame(storedNumberOfChannels, storedSampleRate, storedBitrate);
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};
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const encode = (audioData: ArrayBuffer, numberOfFrames: number) => {
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if (needsReset) {
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reset();
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needsReset = false;
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}
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const audioBytes = new Uint8Array(audioData);
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const sizePerChannel = audioBytes.length / storedNumberOfChannels;
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inputSlice = maybeGrowSlice(inputSlice, audioBytes.length);
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module.HEAPU8.set(audioBytes, inputSlice.ptr);
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const requiredOutputSize = Math.ceil(1.25 * numberOfFrames + 7200);
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outputSlice = maybeGrowSlice(outputSlice, requiredOutputSize);
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const bytesWritten = encodeSamples(
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lamePtr,
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inputSlice.ptr,
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inputSlice.ptr + (storedNumberOfChannels - 1) * sizePerChannel,
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numberOfFrames,
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outputSlice.ptr,
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requiredOutputSize,
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);
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const result = module.HEAPU8.slice(outputSlice.ptr, outputSlice.ptr + bytesWritten);
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return result.buffer;
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};
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const flush = () => {
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if (needsReset) {
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reset();
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needsReset = false;
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}
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const requiredOutputSize = 7200;
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outputSlice = maybeGrowSlice(outputSlice, requiredOutputSize);
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const bytesWritten = flushLame(lamePtr, outputSlice.ptr, requiredOutputSize);
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const result = module.HEAPU8.slice(outputSlice.ptr, outputSlice.ptr + bytesWritten);
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needsReset = true; // After a flush, the encoder must be prepared to start a new encoding process
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return result.buffer;
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};
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/** A "fat pointer" type thing. */
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type Slice = {
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ptr: number;
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size: number;
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};
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/** Either returns the existing slice, or allocates a new one if there's no existing slice or it was too small. */
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const maybeGrowSlice = (slice: Slice | null, requiredSize: number) => {
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if (!slice || slice.size < requiredSize) {
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if (slice) {
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module._free(slice.ptr);
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}
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return {
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ptr: module._malloc(requiredSize),
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size: requiredSize,
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};
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}
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return slice;
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};
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const onMessage = (data: { id: number; command: WorkerCommand }) => {
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const { id, command } = data;
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const handleCommand = async (): Promise<void> => {
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try {
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let result: WorkerResponseData;
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const transferables: Transferable[] = [];
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switch (command.type) {
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case 'init': {
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await init(
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command.data.numberOfChannels,
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command.data.sampleRate,
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command.data.bitrate,
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);
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result = { success: true };
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}; break;
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case 'encode': {
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const encodedData = encode(
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command.data.audioData,
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command.data.numberOfFrames,
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);
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result = { encodedData };
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transferables.push(encodedData);
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}; break;
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case 'flush': {
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const flushedData = flush();
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result = { flushedData };
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transferables.push(flushedData);
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}; break;
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}
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const response: WorkerResponse = {
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id,
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success: true,
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data: result,
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};
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sendMessage(response, transferables);
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} catch (error) {
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const response: WorkerResponse = {
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id,
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success: false,
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error,
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};
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sendMessage(response);
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}
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};
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void handleCommand();
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};
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const sendMessage = (data: unknown, transferables?: Transferable[]) => {
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if (parentPort) {
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parentPort.postMessage(data, transferables ?? []);
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} else {
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self.postMessage(data, { transfer: transferables ?? [] });
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}
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};
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let parentPort: {
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postMessage: (data: unknown, transferables?: Transferable[]) => void;
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on: (event: string, listener: (data: never) => void) => void;
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} | null = null;
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if (typeof self === 'undefined') {
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// We're in Node.js (or a runtime that mimics it)
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const workerModule = 'worker_threads';
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// eslint-disable-next-line @stylistic/max-len
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// eslint-disable-next-line @typescript-eslint/no-require-imports, @typescript-eslint/no-unsafe-assignment, @typescript-eslint/no-unsafe-member-access
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parentPort = require(workerModule).parentPort;
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}
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if (parentPort) {
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parentPort.on('message', onMessage);
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} else {
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self.addEventListener('message', event => onMessage(event.data as { id: number; command: WorkerCommand }));
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}
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@@ -0,0 +1,211 @@
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/*!
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* Copyright (c) 2025-present, Vanilagy and contributors
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/.
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*/
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import { CustomAudioEncoder, AudioCodec, AudioSample, EncodedPacket, registerEncoder } from 'mediabunny';
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import { FRAME_HEADER_SIZE, readFrameHeader } from '../../../shared/mp3-misc';
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import type { WorkerCommand, WorkerResponse, WorkerResponseData } from './shared';
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// @ts-expect-error An esbuild plugin handles this, TypeScript doesn't need to understand
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import createWorker from './encode.worker';
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class Mp3Encoder extends CustomAudioEncoder {
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private worker!: Worker;
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private nextMessageId = 0;
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private pendingMessages = new Map<number, {
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resolve: (value: WorkerResponseData) => void;
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reject: (reason?: unknown) => void;
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}>();
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private buffer = new Uint8Array(2 ** 16);
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private currentBufferOffset = 0;
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private currentTimestamp = 0;
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private chunkMetadata!: EncodedAudioChunkMetadata;
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static override supports(codec: AudioCodec, config: AudioDecoderConfig): boolean {
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return codec === 'mp3'
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&& (config.numberOfChannels === 1 || config.numberOfChannels === 2)
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&& (config.sampleRate === 32000 || config.sampleRate === 44100 || config.sampleRate === 48000);
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}
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async init() {
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// eslint-disable-next-line @typescript-eslint/no-unsafe-call
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this.worker = (await createWorker()) as Worker; // The actual encoding takes place in this worker
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const onMessage = (data: WorkerResponse) => {
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const pending = this.pendingMessages.get(data.id);
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assert(pending !== undefined);
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this.pendingMessages.delete(data.id);
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if (data.success) {
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pending.resolve(data.data);
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} else {
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pending.reject(data.error);
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}
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};
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if (this.worker.addEventListener) {
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this.worker.addEventListener('message', event => onMessage(event.data as WorkerResponse));
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} else {
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const nodeWorker = this.worker as unknown as {
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on: (event: string, listener: (data: never) => void) => void;
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};
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nodeWorker.on('message', onMessage);
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}
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assert(this.config.bitrate);
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await this.sendCommand({
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type: 'init',
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data: {
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numberOfChannels: this.config.numberOfChannels,
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sampleRate: this.config.sampleRate,
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bitrate: this.config.bitrate,
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},
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});
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this.chunkMetadata = {
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decoderConfig: {
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codec: 'mp3',
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numberOfChannels: this.config.numberOfChannels,
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sampleRate: this.config.sampleRate,
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},
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};
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}
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async encode(audioSample: AudioSample) {
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const sizePerChannel = audioSample.allocationSize({
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format: 's16-planar',
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planeIndex: 0,
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});
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const requiredBytes = audioSample.numberOfChannels * sizePerChannel;
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const audioData = new ArrayBuffer(requiredBytes);
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const audioBytes = new Uint8Array(audioData);
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for (let i = 0; i < audioSample.numberOfChannels; i++) {
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audioSample.copyTo(audioBytes.subarray(i * sizePerChannel), {
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format: 's16-planar', // LAME wants it in this format
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planeIndex: i,
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});
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}
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const result = await this.sendCommand({
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type: 'encode',
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data: {
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audioData,
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numberOfFrames: audioSample.numberOfFrames,
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},
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}, [audioData]);
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assert('encodedData' in result);
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this.digestOutput(new Uint8Array(result.encodedData));
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}
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async flush() {
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const result = await this.sendCommand({ type: 'flush' });
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assert('flushedData' in result);
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this.digestOutput(new Uint8Array(result.flushedData));
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}
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close() {
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this.worker.terminate();
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}
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/**
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* LAME returns data in chunks, but a chunk doesn't need to contain a full MP3 frame. Therefore, we must accumulate
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* these chunks and extract the MP3 frames only when they're complete.
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*/
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private digestOutput(bytes: Uint8Array) {
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const requiredBufferSize = this.currentBufferOffset + bytes.length;
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if (requiredBufferSize > this.buffer.length) {
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// Grow the buffer to the required size
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const newSize = 1 << Math.ceil(Math.log2(requiredBufferSize));
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const newBuffer = new Uint8Array(newSize);
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newBuffer.set(this.buffer);
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this.buffer = newBuffer;
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}
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this.buffer.set(bytes, this.currentBufferOffset);
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this.currentBufferOffset = requiredBufferSize;
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let pos = 0;
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while (pos <= this.currentBufferOffset - FRAME_HEADER_SIZE) {
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const word = new DataView(this.buffer.buffer).getUint32(pos, false);
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const header = readFrameHeader(word, { pos, fileSize: null });
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if (!header) {
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break;
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}
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const fits = header.totalSize <= this.currentBufferOffset - pos;
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if (!fits) {
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// The frame isn't complete yet
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break;
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}
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const data = this.buffer.slice(pos, pos + header.totalSize);
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const duration = header.audioSamplesInFrame / header.sampleRate;
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this.onPacket(new EncodedPacket(data, 'key', this.currentTimestamp, duration), this.chunkMetadata);
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if (this.currentTimestamp === 0) {
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this.chunkMetadata = {}; // Mimic WebCodecs-like behavior
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}
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this.currentTimestamp += duration;
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pos += header.totalSize;
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}
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if (pos > 0) {
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// Shift the data
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this.buffer.set(this.buffer.subarray(pos, this.currentBufferOffset), 0);
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this.currentBufferOffset -= pos;
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}
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}
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||||
|
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private sendCommand(
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command: WorkerCommand,
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transferables?: Transferable[],
|
||||
) {
|
||||
return new Promise<WorkerResponseData>((resolve, reject) => {
|
||||
const id = this.nextMessageId++;
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this.pendingMessages.set(id, { resolve, reject });
|
||||
|
||||
if (transferables) {
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||||
this.worker.postMessage({ id, command }, transferables);
|
||||
} else {
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this.worker.postMessage({ id, command });
|
||||
}
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||||
});
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||||
}
|
||||
}
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||||
|
||||
/**
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* Registers the LAME MP3 encoder, which Mediabunny will then use automatically when applicable. Make sure to call this
|
||||
* function before starting any encoding task.
|
||||
*
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||||
* Preferably, wrap the call in a condition to avoid overriding any native MP3 encoder:
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||||
*
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||||
* ```ts
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||||
* import { canEncodeAudio } from 'mediabunny';
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||||
* import { registerMp3Encoder } from '@mediabunny/mp3-encoder';
|
||||
*
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||||
* if (!(await canEncodeAudio('mp3'))) {
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||||
* registerMp3Encoder();
|
||||
* }
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||||
* ```
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||||
*
|
||||
* @public
|
||||
*/
|
||||
export const registerMp3Encoder = () => {
|
||||
registerEncoder(Mp3Encoder);
|
||||
};
|
||||
|
||||
function assert(x: unknown): asserts x {
|
||||
if (!x) {
|
||||
throw new Error('Assertion failed.');
|
||||
}
|
||||
}
|
||||
@@ -0,0 +1,40 @@
|
||||
/*!
|
||||
* Copyright (c) 2025-present, Vanilagy and contributors
|
||||
*
|
||||
* This Source Code Form is subject to the terms of the Mozilla Public
|
||||
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
||||
* file, You can obtain one at https://mozilla.org/MPL/2.0/.
|
||||
*/
|
||||
|
||||
#include <emscripten.h>
|
||||
#include "../lib/lame.h"
|
||||
|
||||
EMSCRIPTEN_KEEPALIVE
|
||||
lame_global_flags *init_lame(int number_of_channels, int sample_rate, int bitrate) {
|
||||
lame_global_flags *gfp = lame_init();
|
||||
|
||||
lame_set_num_channels(gfp, number_of_channels);
|
||||
lame_set_in_samplerate(gfp, sample_rate);
|
||||
lame_set_out_samplerate(gfp, sample_rate);
|
||||
lame_set_brate(gfp, bitrate / 1000); // MP3 wants "kilobitrate"
|
||||
lame_set_bWriteVbrTag(gfp, 0);
|
||||
|
||||
int ret_code = lame_init_params(gfp);
|
||||
|
||||
return gfp;
|
||||
}
|
||||
|
||||
EMSCRIPTEN_KEEPALIVE
|
||||
int encode_samples(lame_global_flags *gfp, short int left_buf[], short int right_buf[], int sample_count, unsigned char *dest_buf, int dest_buf_size) {
|
||||
return lame_encode_buffer(gfp, left_buf, right_buf, sample_count, dest_buf, dest_buf_size);
|
||||
}
|
||||
|
||||
EMSCRIPTEN_KEEPALIVE
|
||||
int flush_lame(lame_global_flags *gfp, unsigned char *dest_buf, int dest_buf_size) {
|
||||
return lame_encode_flush(gfp, dest_buf, dest_buf_size);
|
||||
}
|
||||
|
||||
EMSCRIPTEN_KEEPALIVE
|
||||
void close_lame(lame_global_flags *gfp) {
|
||||
lame_close(gfp);
|
||||
}
|
||||
@@ -0,0 +1,42 @@
|
||||
/*!
|
||||
* Copyright (c) 2025-present, Vanilagy and contributors
|
||||
*
|
||||
* This Source Code Form is subject to the terms of the Mozilla Public
|
||||
* License, v. 2.0. If a copy of the MPL was not distributed with this
|
||||
* file, You can obtain one at https://mozilla.org/MPL/2.0/.
|
||||
*/
|
||||
|
||||
export type WorkerCommand = {
|
||||
type: 'init';
|
||||
data: {
|
||||
numberOfChannels: number;
|
||||
sampleRate: number;
|
||||
bitrate: number;
|
||||
};
|
||||
} | {
|
||||
type: 'encode';
|
||||
data: {
|
||||
audioData: ArrayBuffer;
|
||||
numberOfFrames: number;
|
||||
};
|
||||
} | {
|
||||
type: 'flush';
|
||||
};
|
||||
|
||||
export type WorkerResponseData = {
|
||||
success: boolean;
|
||||
} | {
|
||||
encodedData: ArrayBuffer;
|
||||
} | {
|
||||
flushedData: ArrayBuffer;
|
||||
};
|
||||
|
||||
export type WorkerResponse = {
|
||||
id: number;
|
||||
} & ({
|
||||
success: true;
|
||||
data: WorkerResponseData;
|
||||
} | {
|
||||
success: false;
|
||||
error: unknown;
|
||||
});
|
||||
@@ -0,0 +1,23 @@
|
||||
{
|
||||
"extends": "../../../tsconfig.json",
|
||||
"compilerOptions": {
|
||||
"outDir": "../dist/modules",
|
||||
"declaration": true,
|
||||
"declarationMap": true,
|
||||
"stripInternal": true,
|
||||
"noEmit": false,
|
||||
"moduleResolution": "nodenext",
|
||||
"module": "nodenext",
|
||||
"allowJs": true,
|
||||
"paths": {
|
||||
"mediabunny": ["../../../src/index.ts"],
|
||||
},
|
||||
},
|
||||
"include": [
|
||||
"**/*",
|
||||
"../../../shared/**/*"
|
||||
],
|
||||
"references": [
|
||||
{ "path": "../../../src" }
|
||||
]
|
||||
}
|
||||
Reference in New Issue
Block a user