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A pure JavaScript implementation of the metaflac (the official FLAC tool written in C++) (The userscript port for https://github.com/ishowshao/metaflac-js/tree/master)
このスクリプトは単体で利用できません。右のようなメタデータを含むスクリプトから、ライブラリとして読み込まれます: // @require https://update.greasyfork.org/scripts/482520/1298549/metaflacjs.js
/* eslint-disable no-multi-spaces */
/* eslint-disable no-return-assign */
// ==UserScript==
// @name metaflac.js
// @namespace https://github.com/ishowshao/metaflac-js/
// @version 0.1.4.1
// @description A pure JavaScript implementation of the metaflac (the official FLAC tool written in C++) (The userscript port for https://github.com/ishowshao/metaflac-js/tree/master)
// @author ishowshao, PY-DNG
// @license https://github.com/ishowshao/metaflac-js/
// ==/UserScript==
/* global BufferExport */
// !IMPORTANT! THIS USERSCRIPT LIBRARY REQUIRES https://greasyfork.org/scripts/482519-buffer TO WORK!
let Metaflac = await (async function __MAIN__() {
'use strict';
const Buffer = BufferExport.Buffer;
const FileType = await import('https://fastly.jsdelivr.net/npm/file-type@18.7.0/+esm');
const formatVorbisComment = (function() {
return (vendorString, commentList) => {
const bufferArray = [];
const vendorStringBuffer = Buffer.from(vendorString, 'utf8');
const vendorLengthBuffer = Buffer.alloc(4);
vendorLengthBuffer.writeUInt32LE(vendorStringBuffer.length);
const userCommentListLengthBuffer = Buffer.alloc(4);
userCommentListLengthBuffer.writeUInt32LE(commentList.length);
bufferArray.push(vendorLengthBuffer, vendorStringBuffer, userCommentListLengthBuffer);
for (let i = 0; i < commentList.length; i++) {
const comment = commentList[i];
const commentBuffer = Buffer.from(comment, 'utf8');
const lengthBuffer = Buffer.alloc(4);
lengthBuffer.writeUInt32LE(commentBuffer.length);
bufferArray.push(lengthBuffer, commentBuffer);
}
return Buffer.concat(bufferArray);
}
})();
const BLOCK_TYPE = {
0: 'STREAMINFO',
1: 'PADDING',
2: 'APPLICATION',
3: 'SEEKTABLE',
4: 'VORBIS_COMMENT', // There may be only one VORBIS_COMMENT block in a stream.
5: 'CUESHEET',
6: 'PICTURE',
};
const STREAMINFO = 0;
const PADDING = 1;
const APPLICATION = 2;
const SEEKTABLE = 3;
const VORBIS_COMMENT = 4;
const CUESHEET = 5;
const PICTURE = 6;
class Metaflac {
constructor(flac) {
if (typeof flac !== 'string' && typeof flac !== 'string' && !Buffer.isBuffer(flac)) {
throw new Error('Metaflac(flac) flac must be string or buffer.');
}
this.flac = flac;
this.buffer = null;
this.marker = '';
this.streamInfo = null;
this.blocks = [];
this.padding = null;
this.vorbisComment = null;
this.vendorString = '';
this.tags = [];
this.pictures = [];
this.picturesSpecs = [];
this.picturesDatas = [];
this.framesOffset = 0;
this.init();
}
async init() {
typeof this.flac === 'string' ? this.buffer = await fetchArrayBuffer(this.flac) : this.buffer = this.flac;
let offset = 0;
const marker = this.buffer.slice(0, offset += 4).toString('ascii');
if (marker !== 'fLaC') {
throw new Error('The file does not appear to be a FLAC file.');
}
let blockType = 0;
let isLastBlock = false;
while (!isLastBlock) {
blockType = this.buffer.readUInt8(offset++);
isLastBlock = blockType > 128;
blockType = blockType % 128;
// console.log('Block Type: %d %s', blockType, BLOCK_TYPE[blockType]);
const blockLength = this.buffer.readUIntBE(offset, 3);
offset += 3;
if (blockType === STREAMINFO) {
this.streamInfo = this.buffer.slice(offset, offset + blockLength);
}
if (blockType === PADDING) {
this.padding = this.buffer.slice(offset, offset + blockLength);
}
if (blockType === VORBIS_COMMENT) {
this.vorbisComment = this.buffer.slice(offset, offset + blockLength);
this.parseVorbisComment();
}
if (blockType === PICTURE) {
this.pictures.push(this.buffer.slice(offset, offset + blockLength));
this.parsePictureBlock();
}
if ([APPLICATION, SEEKTABLE, CUESHEET].includes(blockType)) {
this.blocks.push([blockType, this.buffer.slice(offset, offset + blockLength)]);
}
// console.log('Block Length: %d', blockLength);
offset += blockLength;
}
this.framesOffset = offset;
}
parseVorbisComment() {
const vendorLength = this.vorbisComment.readUInt32LE(0);
// console.log('Vendor length: %d', vendorLength);
this.vendorString = this.vorbisComment.slice(4, vendorLength + 4).toString('utf8');
// console.log('Vendor string: %s', this.vendorString);
const userCommentListLength = this.vorbisComment.readUInt32LE(4 + vendorLength);
// console.log('user_comment_list_length: %d', userCommentListLength);
const userCommentListBuffer = this.vorbisComment.slice(4 + vendorLength + 4);
for (let offset = 0; offset < userCommentListBuffer.length; ) {
const length = userCommentListBuffer.readUInt32LE(offset);
offset += 4;
const comment = userCommentListBuffer.slice(offset, offset += length).toString('utf8');
// console.log('Comment length: %d, this.buffer: %s', length, comment);
this.tags.push(comment);
}
}
parsePictureBlock() {
this.pictures.forEach(picture => {
let offset = 0;
const type = picture.readUInt32BE(offset);
offset += 4;
const mimeTypeLength = picture.readUInt32BE(offset);
offset += 4;
const mime = picture.slice(offset, offset + mimeTypeLength).toString('ascii');
offset += mimeTypeLength;
const descriptionLength = picture.readUInt32BE(offset);
offset += 4;
const description = picture.slice(offset, offset += descriptionLength).toString('utf8');
const width = picture.readUInt32BE(offset);
offset += 4;
const height = picture.readUInt32BE(offset);
offset += 4;
const depth = picture.readUInt32BE(offset);
offset += 4;
const colors = picture.readUInt32BE(offset);
offset += 4;
const pictureDataLength = picture.readUInt32BE(offset);
offset += 4;
this.picturesDatas.push(picture.slice(offset, offset + pictureDataLength));
this.picturesSpecs.push(this.buildSpecification({
type,
mime,
description,
width,
height,
depth,
colors
}));
});
}
getPicturesSpecs() {
return this.picturesSpecs;
}
/**
* Get the MD5 signature from the STREAMINFO block.
*/
getMd5sum() {
return this.streamInfo.slice(18, 34).toString('hex');
}
/**
* Get the minimum block size from the STREAMINFO block.
*/
getMinBlocksize() {
return this.streamInfo.readUInt16BE(0);
}
/**
* Get the maximum block size from the STREAMINFO block.
*/
getMaxBlocksize() {
return this.streamInfo.readUInt16BE(2);
}
/**
* Get the minimum frame size from the STREAMINFO block.
*/
getMinFramesize() {
return this.streamInfo.readUIntBE(4, 3);
}
/**
* Get the maximum frame size from the STREAMINFO block.
*/
getMaxFramesize() {
return this.streamInfo.readUIntBE(7, 3);
}
/**
* Get the sample rate from the STREAMINFO block.
*/
getSampleRate() {
// 20 bits number
return this.streamInfo.readUIntBE(10, 3) >> 4;
}
/**
* Get the number of channels from the STREAMINFO block.
*/
getChannels() {
// 3 bits
return this.streamInfo.readUIntBE(10, 3) & 0x00000f >> 1;
}
/**
* Get the # of bits per sample from the STREAMINFO block.
*/
getBps() {
return this.streamInfo.readUIntBE(12, 2) & 0x01f0 >> 4;
}
/**
* Get the total # of samples from the STREAMINFO block.
*/
getTotalSamples() {
return this.streamInfo.readUIntBE(13, 5) & 0x0fffffffff;
}
/**
* Show the vendor string from the VORBIS_COMMENT block.
*/
getVendorTag() {
return this.vendorString;
}
/**
* Get all tags where the the field name matches NAME.
*
* @param {string} name
*/
getTag(name) {
return this.tags.filter(item => {
const itemName = item.split('=')[0];
return itemName === name;
}).join('\n');
}
/**
* Remove all tags whose field name is NAME.
*
* @param {string} name
*/
removeTag(name) {
this.tags = this.tags.filter(item => {
const itemName = item.split('=')[0];
return itemName !== name;
});
}
/**
* Remove first tag whose field name is NAME.
*
* @param {string} name
*/
removeFirstTag(name) {
const found = this.tags.findIndex(item => {
return item.split('=')[0] === name;
});
if (found !== -1) {
this.tags.splice(found, 1);
}
}
/**
* Remove all tags, leaving only the vendor string.
*/
removeAllTags() {
this.tags = [];
}
/**
* Add a tag.
* The FIELD must comply with the Vorbis comment spec, of the form NAME=VALUE. If there is currently no tag block, one will be created.
*
* @param {string} field
*/
setTag(field) {
if (field.indexOf('=') === -1) {
throw new Error(`malformed vorbis comment field "${field}", field contains no '=' character`);
}
this.tags.push(field);
}
/**
* Like setTag, except the VALUE is a filename whose contents will be read verbatim to set the tag value.
*
* @param {string} field
*/
async setTagFromFile(field) {
const position = field.indexOf('=');
if (position === -1) {
throw new Error(`malformed vorbis comment field "${field}", field contains no '=' character`);
}
const name = field.substring(0, position);
const filename = field.substr(position + 1);
let value;
try {
value = await readAsText(filename, 'utf8');
} catch (e) {
throw new Error(`can't open file '${filename}' for '${name}' tag value`);
}
this.tags.push(`${name}=${value}`);
}
/**
* Import tags from a file.
* Each line should be of the form NAME=VALUE.
*
* @param {string} filename
*/
async importTagsFrom(filename) {
const tags = await readAsText(filename, 'utf8').split('\n');
tags.forEach(line => {
if (line.indexOf('=') === -1) {
throw new Error(`malformed vorbis comment "${line}", contains no '=' character`);
}
});
this.tags = this.tags.concat(tags);
}
/**
* Export tags to a file.
* Each line will be of the form NAME=VALUE.
*
* @param {string} filename
*/
exportTagsTo(filename) {
dlText(filename, this.tags.join('\n'), 'utf8');
}
/**
* Import a picture and store it in a PICTURE metadata block.
*
* @param {string} filename
*/
async importPictureFrom(filename) {
const picture = await fetchArrayBuffer(filename);
const {mime} = await FileType.fileTypeFromBuffer(picture);
if (mime !== 'image/jpeg' && mime !== 'image/png') {
throw new Error(`only support image/jpeg and image/png picture temporarily, current import ${mime}`);
}
const dimensions = await imageSize(filename);
const spec = this.buildSpecification({
mime: mime,
width: dimensions.width,
height: dimensions.height,
});
this.pictures.push(this.buildPictureBlock(picture, spec));
this.picturesSpecs.push(spec);
}
/**
* Import a picture and store it in a PICTURE metadata block.
*
* @param {Buffer} picture
*/
async importPictureFromBuffer(picture) {
const {mime} = await FileType.fileTypeFromBuffer(picture);
if (mime !== 'image/jpeg' && mime !== 'image/png') {
throw new Error(`only support image/jpeg and image/png picture temporarily, current import ${mime}`);
}
const dimensions = await imageSize(picture);
const spec = this.buildSpecification({
mime: mime,
width: dimensions.width,
height: dimensions.height,
});
this.pictures.push(this.buildPictureBlock(picture, spec));
this.picturesSpecs.push(spec);
}
/**
* Export PICTURE block to a file.
*
* @param {string} filename
*/
exportPictureTo(filename) {
if (this.picturesDatas.length > 0) {
dlText(filename, this.picturesDatas[0]);
}
}
/**
* Return all tags.
*/
getAllTags() {
return this.tags;
}
buildSpecification(spec = {}) {
const defaults = {
type: 3,
mime: 'image/jpeg',
description: '',
width: 0,
height: 0,
depth: 24,
colors: 0,
};
return Object.assign(defaults, spec);
}
/**
* Build a picture block.
*
* @param {Buffer} picture
* @param {Object} specification
* @returns {Buffer}
*/
buildPictureBlock(picture, specification = {}) {
const pictureType = Buffer.alloc(4);
const mimeLength = Buffer.alloc(4);
const mime = Buffer.from(specification.mime, 'ascii');
const descriptionLength = Buffer.alloc(4);
const description = Buffer.from(specification.description, 'utf8');
const width = Buffer.alloc(4);
const height = Buffer.alloc(4);
const depth = Buffer.alloc(4);
const colors = Buffer.alloc(4);
const pictureLength = Buffer.alloc(4);
pictureType.writeUInt32BE(specification.type);
mimeLength.writeUInt32BE(specification.mime.length);
descriptionLength.writeUInt32BE(specification.description.length);
width.writeUInt32BE(specification.width);
height.writeUInt32BE(specification.height);
depth.writeUInt32BE(specification.depth);
colors.writeUInt32BE(specification.colors);
pictureLength.writeUInt32BE(picture.length);
return Buffer.concat([
pictureType,
mimeLength,
mime,
descriptionLength,
description,
width,
height,
depth,
colors,
pictureLength,
picture,
]);
}
buildMetadataBlock(type, block, isLast = false) {
const header = Buffer.alloc(4);
if (isLast) {
type += 128;
}
header.writeUIntBE(type, 0, 1);
header.writeUIntBE(block.length, 1, 3);
return Buffer.concat([header, block]);
}
buildMetadata() {
const bufferArray = [];
bufferArray.push(this.buildMetadataBlock(STREAMINFO, this.streamInfo));
this.blocks.forEach(block => {
bufferArray.push(this.buildMetadataBlock(...block));
});
bufferArray.push(this.buildMetadataBlock(VORBIS_COMMENT, formatVorbisComment(this.vendorString, this.tags)));
this.pictures.forEach(block => {
bufferArray.push(this.buildMetadataBlock(PICTURE, block));
});
bufferArray.push(this.buildMetadataBlock(PADDING, this.padding, true));
return bufferArray;
}
buildStream() {
const metadata = this.buildMetadata();
return [this.buffer.slice(0, 4), ...metadata, this.buffer.slice(this.framesOffset)];
}
/**
* Save change to file or return changed buffer.
*/
save() {
if (typeof this.flac === 'string') {
dlText(this.flac, Buffer.concat(this.buildStream()));
} else {
return Buffer.concat(this.buildStream());
}
}
}
return Metaflac;
function fetchArrayBuffer(url) {
return fetchBlob(url).then(blob => readAsArrayBuffer(blob));
}
function fetchBlob(url) {
return new Promise(function (resolve, reject) {
GM_xmlhttpRequest({
method: 'GET', url,
responseType: 'blob',
onerror: reject,
onload: res => resolve(res.response)
});
});
}
function readAsArrayBuffer(file) {
return new Promise(function (resolve, reject) {
const reader = new FileReader();
reader.onload = () => {
resolve(reader.result);
};
reader.onerror = reject;
reader.readAsArrayBuffer(file);
});
}
function readAsText(file, encoding) {
return new Promise(function (resolve, reject) {
const reader = new FileReader();
reader.onload = () => {
resolve(reader.result);
};
reader.onerror = reject;
reader.readAsText(file, encoding);
});
}
// Save text to textfile
function dlText(name, text, charset='utf-8') {
if (!text || !name) {return false;};
// Get blob url
const blob = new Blob([text],{type:`text/plain;charset=${charset}`});
const url = URL.createObjectURL(blob);
// Create <a> and download
const a = document.createElement('a');
a.href = url;
a.download = name;
a.click();
}
function imageSize(urlOrArrayBuffer) {
let url = urlOrArrayBuffer, isObjURL = false;
if (typeof url !== 'string') {
url = URL.createObjectURL(new Blob([urlOrArrayBuffer]));
isObjURL = true;
}
return new Promise((resolve, reject) => {
const img = new Image();
img.src = url;
img.onload = () => {
resolve({
height: img.naturalHeight,
width: img.naturalWidth
});
isObjURL && URL.revokeObjectURL(url);
}
img.onerror = err => {
reject(err);
isObjURL && URL.revokeObjectURL(url);
}
});
}
function _arrayBufferToBlobURL(buffer) {
const blob = new Blob([buffer]);
const url = URL.createObjectURL(blob);
return url;
}
})();