Borewit
118 lines
4.8 KiB
TypeScript
118 lines
4.8 KiB
TypeScript
import type { IGetToken } from 'strtok3';
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import * as util from '../common/Util.js';
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import { UINT16_BE, UINT24_BE, Uint8ArrayType } from 'token-types';
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/**
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* FLAC supports up to 128 kinds of metadata blocks; currently the following are defined:
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* ref: https://xiph.org/flac/format.html#metadata_block
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*/
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export const BlockType = {
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STREAMINFO: 0, // STREAMINFO
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PADDING: 1, // PADDING
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APPLICATION: 2, // APPLICATION
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SEEKTABLE: 3, // SEEKTABLE
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VORBIS_COMMENT: 4, // VORBIS_COMMENT
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CUESHEET: 5, // CUESHEET
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PICTURE: 6 // PICTURE
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};
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export type BlockType = typeof BlockType[keyof typeof BlockType];
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/**
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* METADATA_BLOCK_DATA
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* Ref: https://xiph.org/flac/format.html#metadata_block_streaminfo
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*/
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export interface IBlockHeader {
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// Last-metadata-block flag: '1' if this block is the last metadata block before the audio blocks, '0' otherwise.
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lastBlock: boolean,
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// BLOCK_TYPE
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type: BlockType,
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// Length (in bytes) of metadata to follow (does not include the size of the METADATA_BLOCK_HEADER)
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length: number;
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}
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export const BlockHeader: IGetToken<IBlockHeader> = {
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len: 4,
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get: (buf: Uint8Array, off: number): IBlockHeader => {
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return {
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lastBlock: util.getBit(buf, off, 7),
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type: util.getBitAllignedNumber(buf, off, 1, 7),
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length: UINT24_BE.get(buf, off + 1)
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};
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}
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};
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/**
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* METADATA_BLOCK_DATA
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* Ref: https://xiph.org/flac/format.html#metadata_block_streaminfo
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*/
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export interface IBlockStreamInfo {
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minimumBlockSize: number,
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// The maximum block size (in samples) used in the stream.
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// (Minimum blocksize == maximum blocksize) implies a fixed-blocksize stream.
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maximumBlockSize: number,
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// The minimum frame size (in bytes) used in the stream.
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// May be 0 to imply the value is not known.
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minimumFrameSize: number,
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// The maximum frame size (in bytes) used in the stream.
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// May be 0 to imply the value is not known.
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maximumFrameSize: number,
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// Sample rate in Hz. Though 20 bits are available,
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// the maximum sample rate is limited by the structure of frame headers to 655350Hz.
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// Also, a value of 0 is invalid.
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sampleRate: number,
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// probably slower: sampleRate: common.getBitAllignedNumber(buf, off + 10, 0, 20),
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// (number of channels)-1. FLAC supports from 1 to 8 channels
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channels: number,
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// bits per sample)-1.
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// FLAC supports from 4 to 32 bits per sample. Currently the reference encoder and decoders only support up to 24 bits per sample.
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bitsPerSample: number,
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// Total samples in stream.
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// 'Samples' means inter-channel sample, i.e. one second of 44.1Khz audio will have 44100 samples regardless of the number of channels.
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// A value of zero here means the number of total samples is unknown.
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totalSamples: number,
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// the MD5 hash of the file (see notes for usage... it's a littly tricky)
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fileMD5: Uint8Array;
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}
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/**
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* METADATA_BLOCK_DATA
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* Ref: https://xiph.org/flac/format.html#metadata_block_streaminfo
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*/
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export const BlockStreamInfo: IGetToken<IBlockStreamInfo> = {
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len: 34,
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get: (buf: Uint8Array, off: number): IBlockStreamInfo => {
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return {
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// The minimum block size (in samples) used in the stream.
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minimumBlockSize: UINT16_BE.get(buf, off),
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// The maximum block size (in samples) used in the stream.
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// (Minimum blocksize == maximum blocksize) implies a fixed-blocksize stream.
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maximumBlockSize: UINT16_BE.get(buf, off + 2) / 1000,
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// The minimum frame size (in bytes) used in the stream.
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// May be 0 to imply the value is not known.
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minimumFrameSize: UINT24_BE.get(buf, off + 4),
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// The maximum frame size (in bytes) used in the stream.
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// May be 0 to imply the value is not known.
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maximumFrameSize: UINT24_BE.get(buf, off + 7),
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// Sample rate in Hz. Though 20 bits are available,
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// the maximum sample rate is limited by the structure of frame headers to 655350Hz.
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// Also, a value of 0 is invalid.
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sampleRate: UINT24_BE.get(buf, off + 10) >> 4,
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// probably slower: sampleRate: common.getBitAllignedNumber(buf, off + 10, 0, 20),
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// (number of channels)-1. FLAC supports from 1 to 8 channels
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channels: util.getBitAllignedNumber(buf, off + 12, 4, 3) + 1,
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// bits per sample)-1.
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// FLAC supports from 4 to 32 bits per sample. Currently the reference encoder and decoders only support up to 24 bits per sample.
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bitsPerSample: util.getBitAllignedNumber(buf, off + 12, 7, 5) + 1,
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// Total samples in stream.
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// 'Samples' means inter-channel sample, i.e. one second of 44.1Khz audio will have 44100 samples regardless of the number of channels.
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// A value of zero here means the number of total samples is unknown.
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totalSamples: util.getBitAllignedNumber(buf, off + 13, 4, 36),
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// the MD5 hash of the file (see notes for usage... it's a littly tricky)
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fileMD5: new Uint8ArrayType(16).get(buf, off + 18)
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};
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}
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};
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