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Create @mediabunny/mp3-encoder, restructure and extend build system

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Vanilagy
2025-08-10 00:45:30 +02:00
parent 7a2a23bcb0
commit cbb2681d33
38 changed files with 2913 additions and 112 deletions
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src/mp3/mp3-demuxer.ts
+1 -1
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@@ -13,7 +13,7 @@ import { InputAudioTrack, InputAudioTrackBacking } from '../input-track';
import { PacketRetrievalOptions } from '../media-sink';
import { assert, binarySearchExact, binarySearchLessOrEqual, last, UNDETERMINED_LANGUAGE } from '../misc';
import { EncodedPacket, PLACEHOLDER_DATA } from '../packet';
import { FrameHeader, getXingOffset, INFO, XING } from './mp3-misc';
import { FrameHeader, getXingOffset, INFO, XING } from '../../shared/mp3-misc';
import { Mp3Reader } from './mp3-reader';
type Sample = {
src/mp3/mp3-misc.ts
-158
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@@ -1,158 +0,0 @@
/*!
* 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 const FRAME_HEADER_SIZE = 4;
// These are in kbps:
export const MPEG_V1_BITRATES: Record<number, number[]> = {
// Layer 3
1: [-1, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, -1],
// Layer 2
2: [-1, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, -1],
// Layer 1
3: [-1, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448, -1],
};
export const MPEG_V2_BITRATES: Record<number, number[]> = {
// Layer 3
1: [-1, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256, -1],
// Layer 2
2: [-1, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, -1],
// Layer 1
3: [-1, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160, -1],
};
export const SAMPLING_RATES: Record<number, number[]> = {
// MPEG Version 2.5
0: [11025, 12000, 8000, -1],
// MPEG Version 2 (ISO/IEC 13818-3)
2: [22050, 24000, 16000, -1],
// MPEG Version 1 (ISO/IEC 11172-3)
3: [44100, 48000, 32000, -1],
};
/** 'Xing' */
export const XING = 0x58696e67;
/** 'Info' */
export const INFO = 0x496e666f;
export type FrameHeader = {
startPos: number;
totalSize: number;
mpegVersionId: number;
layer: number;
bitrate: number;
frequencyIndex: number;
sampleRate: number;
channel: number;
modeExtension: number;
copyright: number;
original: number;
emphasis: number;
audioSamplesInFrame: number;
};
export const computeMp3FrameSize = (layer: number, bitrate: number, sampleRate: number, padding: number) => {
if (layer === 3) {
// Layer 1
return Math.floor((12 * bitrate / sampleRate + padding) * 4);
} else {
return Math.floor((144 * bitrate / sampleRate) + padding);
}
};
export const getXingOffset = (mpegVersionId: number, channel: number) => {
return mpegVersionId === 3
? (channel === 3 ? 21 : 36)
: (channel === 3 ? 13 : 21);
};
export const readFrameHeader = (word: number, reader: { pos: number; fileSize: number | null }): FrameHeader | null => {
const startPos = reader.pos;
const firstByte = word >>> 24;
const secondByte = (word >>> 16) & 0xff;
const thirdByte = (word >>> 8) & 0xff;
const fourthByte = word & 0xff;
if (firstByte !== 0xff && secondByte !== 0xff && thirdByte !== 0xff && fourthByte !== 0xff) {
reader.pos += 4;
return null;
}
reader.pos += 1;
if (firstByte !== 0xff) {
return null;
}
if ((secondByte & 0xe0) !== 0xe0) {
return null;
}
const mpegVersionId = (secondByte >> 3) & 0x3;
const layer = (secondByte >> 1) & 0x3;
const bitrateIndex = (thirdByte >> 4) & 0xf;
const frequencyIndex = (thirdByte >> 2) & 0x3;
const padding = (thirdByte >> 1) & 0x1;
const channel = (fourthByte >> 6) & 0x3;
const modeExtension = (fourthByte >> 4) & 0x3;
const copyright = (fourthByte >> 3) & 0x1;
const original = (fourthByte >> 2) & 0x1;
const emphasis = fourthByte & 0x3;
const kilobitRate = mpegVersionId === 3
? MPEG_V1_BITRATES[layer]?.[bitrateIndex]
: MPEG_V2_BITRATES[layer]?.[bitrateIndex];
if (!kilobitRate || kilobitRate === -1) {
return null;
}
const bitrate = kilobitRate * 1000;
const sampleRate = SAMPLING_RATES[mpegVersionId]?.[frequencyIndex];
if (!sampleRate || sampleRate === -1) {
return null;
}
const frameLength = computeMp3FrameSize(layer, bitrate, sampleRate, padding);
if (reader.fileSize !== null && reader.fileSize - startPos < frameLength) {
// The frame doesn't fit into the rest of the file
return null;
}
let audioSamplesInFrame: number;
if (mpegVersionId === 3) {
audioSamplesInFrame = layer === 3 ? 384 : 1152;
} else {
if (layer === 3) {
audioSamplesInFrame = 384;
} else if (layer === 2) {
audioSamplesInFrame = 1152;
} else {
audioSamplesInFrame = 576;
}
}
return {
startPos: startPos,
totalSize: frameLength,
mpegVersionId,
layer,
bitrate,
frequencyIndex,
sampleRate,
channel,
modeExtension,
copyright,
original,
emphasis,
audioSamplesInFrame,
};
};
src/mp3/mp3-muxer.ts
+1 -1
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@@ -12,7 +12,7 @@ import { Output, OutputAudioTrack } from '../output';
import { Mp3OutputFormat } from '../output-format';
import { EncodedPacket } from '../packet';
import { Writer } from '../writer';
import { getXingOffset, INFO, readFrameHeader, XING } from './mp3-misc';
import { getXingOffset, INFO, readFrameHeader, XING } from '../../shared/mp3-misc';
import { Mp3Writer, XingFrameData } from './mp3-writer';
export class Mp3Muxer extends Muxer {
src/mp3/mp3-reader.ts
+1 -1
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@@ -8,7 +8,7 @@
import { assert } from '../misc';
import { Reader } from '../reader';
import { FRAME_HEADER_SIZE, FrameHeader, readFrameHeader } from './mp3-misc';
import { FRAME_HEADER_SIZE, FrameHeader, readFrameHeader } from '../../shared/mp3-misc';
export class Mp3Reader {
pos = 0;
src/mp3/mp3-writer.ts
+1 -1
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@@ -14,7 +14,7 @@ import {
MPEG_V2_BITRATES,
SAMPLING_RATES,
XING,
} from './mp3-misc';
} from '../../shared/mp3-misc';
export type XingFrameData = {
mpegVersionId: number;