@infinito/id3/src/gen.js

ID3 Tag Reader/Writer

import {TextEncoder} from 'text-encoding';

import {constants} from './constants.js';

import id3Tag from './classes/id3tag.js';

import genID3v2_3 from './gen/id3.2.3.js';

import setSyncSafe from './set.syncsafe.js';

export default function genID3(tags) {
	if(!(tags instanceof id3Tag)) {
		throw new TypeError("tags not of type id3Tag");
	}
	var header = new Uint8Array(constants.ID3_HEADER_LENGTH_BYTES);
	for(var i=0;i<constants.ID3_HEADER_IDENTIFIER_LENGTH_BYTES;i++) {
		header[i] = constants.ID3_HEADER_IDENTIFIER[i];
	}
	var pos = constants.ID3_HEADER_IDENTIFIER_LENGTH_BYTES;
	header[pos] = tags.ver;
	pos++;
	header[pos] = tags.subVer;
	pos++;
	header[pos] = tags.flags;
	pos++;
	switch(tags.ver) {
		case 4:
			throw new Error("id3v2.4."+subver+" not supported");
			break;
		case 3:
			var frames = genID3v2_3(tags);
			var len = constants.ID3_HEADER_LENGTH_BYTES;
			for(var i in frames) {
				len += frames[i].byteLength;
			}
			setSyncSafe(header,pos,len-constants.ID3_HEADER_LENGTH_BYTES,constants.ID3V2_3_FRAME_SIZE_BYTES);
			pos += constants.ID3V2_3_FRAME_SIZE_BYTES;
			var buf = new Uint8Array(len);
			for(var i=0;i<constants.ID3_HEADER_LENGTH_BYTES;i++) {
				buf[i] = header[i];
			}
			for(var i in frames) {
				len = frames[i].byteLength;
				for(var j=0;j<len;j++) {
					buf[pos+j] = frames[i][j];
				}
				pos += len;
			}
			return buf;
		default:
			throw new Error("id3v"+tags.ver+"."+tags.subver+" not supported");
			return;
	}
	var path = new TextEncoder().encode(tags.path);
	var sz = path.byteLength;
	if(sz>0xffff) {
		console.error(tags);
		throw new Error("Path is too long");
		return;
	}
	var pathbuf = new Uint8Array(2+sz);
	pathbuf[0] = (sz&0xff00)>>16;
	pathbuf[1] = sz&0xff;
	for(var i=0;i<path.byteLength;i++) {
		pathbuf[2+i] = path[i];
	}
	var res = new Uint8Array(pathbuf.byteLength+buf.byteLength);
	for(var i=0;i<pathbuf.byteLength;i++) {
		res[i] = pathbuf[i];
	}
	for(var j=0;j<buf.byteLength;j++) {
		res[i+j] = buf[j];
	}
	return res;
};