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import * as ID3Util from './ID3Util' |
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import { |
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FRAME_IDENTIFIERS, |
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FRAME_ALIASES } |
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from "./definitions/FrameIdentifiers" |
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type Flags = { |
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tagAlterPreservation?: boolean |
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fileAlterPreservation?: boolean |
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readOnly?: boolean |
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compression?: boolean |
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encryption?: boolean |
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groupingIdentity?: boolean |
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dataLengthIndicator?: boolean |
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} |
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class FrameHeader { |
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private identifier: string |
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private bodySize: number |
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private flags: Flags |
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constructor(identifier: string, bodySize: number, flags: Flags = {}) { |
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this.identifier = identifier |
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this.bodySize = bodySize |
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this.flags = flags |
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} |
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getBuffer() { |
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const buffer = Buffer.alloc(10) |
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buffer.write(this.identifier, 0) |
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buffer.writeUInt32BE(this.bodySize, 4) |
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return buffer |
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} |
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} |
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export function createFromBuffer(headerBuffer: Buffer, version: number) { |
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const identifierSize = version === 2 ? 3 : 4 |
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let identifier = headerBuffer.toString('utf8', 0, identifierSize) |
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const frameSize = getBodySize(headerBuffer, version) |
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const flags = extractFlags(headerBuffer[8], headerBuffer[9], version) |
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// Try to convert identifier for older versions |
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if (version === 2) { |
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const aliasesV2: Record<string, string> = FRAME_ALIASES.v2 |
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const alias = aliasesV2[identifier] |
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if (alias) { |
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const identifiers: Record<string, string> = FRAME_IDENTIFIERS.v34 |
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identifier = identifiers[alias] |
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} |
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} |
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return new FrameHeader(identifier, frameSize, flags) |
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} |
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function extractFlags( |
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statusFlag: number, |
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encodingFlag: number, |
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version: number |
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) { |
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if (version === 3) { |
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return { |
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tagAlterPreservation: !!(statusFlag & 128), |
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fileAlterPreservation: !!(statusFlag & 64), |
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readOnly: !!(statusFlag & 32), |
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compression: !!(encodingFlag & 128), |
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encryption: !!(encodingFlag & 64), |
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groupingIdentity: !!(encodingFlag & 32), |
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dataLengthIndicator: !!(encodingFlag & 128) |
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} |
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} |
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if (version === 4) { |
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return { |
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tagAlterPreservation: !!(statusFlag & 64), |
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fileAlterPreservation: !!(statusFlag & 32), |
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readOnly: !!(statusFlag & 16), |
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groupingIdentity: !!(encodingFlag & 64), |
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compression: !!(encodingFlag & 8), |
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encryption: !!(encodingFlag & 4), |
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unsynchronisation: !!(encodingFlag & 2), |
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dataLengthIndicator: !!(encodingFlag & 1) |
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} |
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} |
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return {} |
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} |
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export function getHeaderSize(version: number) { |
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return version === 2 ? 6 : 10 |
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} |
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function getBodySize(headerBuffer: Buffer, version: number) { |
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const isEncoded = version === 4 |
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const bytes = version === 2 ? |
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[headerBuffer[3], headerBuffer[4], headerBuffer[5]] : |
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[headerBuffer[4], headerBuffer[5], headerBuffer[6], headerBuffer[7]] |
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if (isEncoded) { |
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return ID3Util.decodeSize(Buffer.from(bytes)) |
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} |
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return Buffer.from(bytes).readUIntBE(0, bytes.length) |
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} |
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export function getFrameSize(buffer: Buffer, version: number) { |
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return getHeaderSize(version) + getBodySize(buffer, version) |
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} |
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Zazama /
node-id3
