music-metadata
Version:
Music metadata parser for Node.js, supporting virtual any audio and tag format.
57 lines (56 loc) • 2.72 kB
JavaScript
import initDebug from 'debug';
import { BasicParser } from '../../common/BasicParser.js';
import { tryParseApeHeader } from '../../apev2/APEv2Parser.js';
import { FourCcToken } from '../../common/FourCC.js';
import * as SV8 from './StreamVersion8.js';
import { MusepackContentError } from '../MusepackConentError.js';
const debug = initDebug('music-metadata:parser:musepack');
export class MpcSv8Parser extends BasicParser {
constructor() {
super(...arguments);
this.audioLength = 0;
}
async parse() {
const signature = await this.tokenizer.readToken(FourCcToken);
if (signature !== 'MPCK')
throw new MusepackContentError('Invalid Magic number');
this.metadata.setFormat('container', 'Musepack, SV8');
return this.parsePacket();
}
async parsePacket() {
const sv8reader = new SV8.StreamReader(this.tokenizer);
do {
const header = await sv8reader.readPacketHeader();
debug(`packet-header key=${header.key}, payloadLength=${header.payloadLength}`);
switch (header.key) {
case 'SH': { // Stream Header
const sh = await sv8reader.readStreamHeader(header.payloadLength);
this.metadata.setFormat('numberOfSamples', sh.sampleCount);
this.metadata.setFormat('sampleRate', sh.sampleFrequency);
this.metadata.setFormat('duration', sh.sampleCount / sh.sampleFrequency);
this.metadata.setFormat('numberOfChannels', sh.channelCount);
break;
}
case 'AP': // Audio Packet
this.audioLength += header.payloadLength;
await this.tokenizer.ignore(header.payloadLength);
break;
case 'RG': // Replaygain
case 'EI': // Encoder Info
case 'SO': // Seek Table Offset
case 'ST': // Seek Table
case 'CT': // Chapter-Tag
await this.tokenizer.ignore(header.payloadLength);
break;
case 'SE': // Stream End
if (this.metadata.format.duration) {
this.metadata.setFormat('bitrate', this.audioLength * 8 / this.metadata.format.duration);
}
return tryParseApeHeader(this.metadata, this.tokenizer, this.options);
default:
throw new MusepackContentError(`Unexpected header: ${header.key}`);
}
// biome-ignore lint/correctness/noConstantCondition: break is handled in the switch statement
} while (true);
}
}