59 lines
2.4 KiB
JavaScript
59 lines
2.4 KiB
JavaScript
import * as Token from 'token-types';
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import { FourCcToken } from '../common/FourCC.js';
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import { makeUnexpectedFileContentError } from '../ParseError.js';
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export const compressionTypes = {
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NONE: 'not compressed PCM Apple Computer',
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sowt: 'PCM (byte swapped)',
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fl32: '32-bit floating point IEEE 32-bit float',
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fl64: '64-bit floating point IEEE 64-bit float Apple Computer',
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alaw: 'ALaw 2:1 8-bit ITU-T G.711 A-law',
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ulaw: 'µLaw 2:1 8-bit ITU-T G.711 µ-law Apple Computer',
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ULAW: 'CCITT G.711 u-law 8-bit ITU-T G.711 µ-law',
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ALAW: 'CCITT G.711 A-law 8-bit ITU-T G.711 A-law',
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FL32: 'Float 32 IEEE 32-bit float '
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};
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export class AiffContentError extends makeUnexpectedFileContentError('AIFF') {
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}
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export class Common {
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constructor(header, isAifc) {
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this.isAifc = isAifc;
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const minimumChunkSize = isAifc ? 22 : 18;
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if (header.chunkSize < minimumChunkSize)
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throw new AiffContentError(`COMMON CHUNK size should always be at least ${minimumChunkSize}`);
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this.len = header.chunkSize;
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}
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get(buf, off) {
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// see: https://cycling74.com/forums/aiffs-80-bit-sample-rate-value
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const shift = Token.UINT16_BE.get(buf, off + 8) - 16398;
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const baseSampleRate = Token.UINT16_BE.get(buf, off + 8 + 2);
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const res = {
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numChannels: Token.UINT16_BE.get(buf, off),
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numSampleFrames: Token.UINT32_BE.get(buf, off + 2),
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sampleSize: Token.UINT16_BE.get(buf, off + 6),
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sampleRate: shift < 0 ? baseSampleRate >> Math.abs(shift) : baseSampleRate << shift
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};
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if (this.isAifc) {
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res.compressionType = FourCcToken.get(buf, off + 18);
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if (this.len > 22) {
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const strLen = Token.UINT8.get(buf, off + 22);
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if (strLen > 0) {
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const padding = (strLen + 1) % 2;
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if (23 + strLen + padding === this.len) {
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res.compressionName = new Token.StringType(strLen, 'latin1').get(buf, off + 23);
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}
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else {
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throw new AiffContentError('Illegal pstring length');
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}
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}
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else {
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res.compressionName = undefined;
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}
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}
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}
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else {
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res.compressionName = 'PCM';
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}
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return res;
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}
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}
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