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Add @mediabunny/aac-encoder extension package

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This commit is contained in:
Vanilagy
2026-03-04 17:05:34 +01:00
parent 76e0703b13
commit c4398fb88c
51 changed files with 1976 additions and 274 deletions
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src/codec.ts
+1 -101
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@@ -6,6 +6,7 @@
* file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/
import { parseAacAudioSpecificConfig } from '../shared/aac-misc';
import {
Av1CodecInfo,
AvcDecoderConfigurationRecord,
@@ -13,7 +14,6 @@ import {
Vp9CodecInfo,
} from './codec-data';
import {
Bitstream,
COLOR_PRIMARIES_MAP,
MATRIX_COEFFICIENTS_MAP,
TRANSFER_CHARACTERISTICS_MAP,
@@ -590,106 +590,6 @@ export const extractAudioCodecString = (trackInfo: {
throw new TypeError(`Unhandled codec '${codec}'.`);
};
export type AacAudioSpecificConfig = {
objectType: number;
frequencyIndex: number;
sampleRate: number | null;
channelConfiguration: number;
numberOfChannels: number | null;
};
export const aacFrequencyTable = [
96000, 88200, 64000, 48000, 44100, 32000,
24000, 22050, 16000, 12000, 11025, 8000, 7350,
];
export const aacChannelMap = [-1, 1, 2, 3, 4, 5, 6, 8];
export const parseAacAudioSpecificConfig = (bytes: Uint8Array | null): AacAudioSpecificConfig => {
if (!bytes || bytes.byteLength < 2) {
throw new TypeError('AAC description must be at least 2 bytes long.');
}
const bitstream = new Bitstream(bytes);
let objectType = bitstream.readBits(5);
if (objectType === 31) {
objectType = 32 + bitstream.readBits(6);
}
const frequencyIndex = bitstream.readBits(4);
let sampleRate: number | null = null;
if (frequencyIndex === 15) {
sampleRate = bitstream.readBits(24);
} else {
if (frequencyIndex < aacFrequencyTable.length) {
sampleRate = aacFrequencyTable[frequencyIndex]!;
}
}
const channelConfiguration = bitstream.readBits(4);
let numberOfChannels: number | null = null;
if (channelConfiguration >= 1 && channelConfiguration <= 7) {
numberOfChannels = aacChannelMap[channelConfiguration]!;
}
return {
objectType,
frequencyIndex,
sampleRate,
channelConfiguration,
numberOfChannels,
};
};
export const buildAacAudioSpecificConfig = (config: {
objectType: number;
sampleRate: number;
numberOfChannels: number;
}) => {
let frequencyIndex = aacFrequencyTable.indexOf(config.sampleRate);
let customSampleRate: number | null = null;
if (frequencyIndex === -1) {
frequencyIndex = 15;
customSampleRate = config.sampleRate;
}
const channelConfiguration = aacChannelMap.indexOf(config.numberOfChannels);
if (channelConfiguration === -1) {
throw new TypeError(`Unsupported number of channels: ${config.numberOfChannels}`);
}
let bitCount = 5 + 4 + 4;
if (config.objectType >= 32) {
bitCount += 6;
}
if (frequencyIndex === 15) {
bitCount += 24;
}
const byteCount = Math.ceil(bitCount / 8);
const bytes = new Uint8Array(byteCount);
const bitstream = new Bitstream(bytes);
if (config.objectType < 32) {
bitstream.writeBits(5, config.objectType);
} else {
bitstream.writeBits(5, 31);
bitstream.writeBits(6, config.objectType - 32);
}
bitstream.writeBits(4, frequencyIndex);
if (frequencyIndex === 15) {
bitstream.writeBits(24, customSampleRate!);
}
bitstream.writeBits(4, channelConfiguration);
return bytes;
};
export const OPUS_SAMPLE_RATE = 48_000;
const PCM_CODEC_REGEX = /^pcm-([usf])(\d+)+(be)?$/;