Initial working version

2022-12-22 20:22:22 +11:00
parent ce9675a1cc
commit ced7fa5092
902 changed files with 150252 additions and 0 deletions
@@ -0,0 +1,124 @@
+var utils = require('./utils');
+
+function checkMagicId3(view, offset) {
+	var id3Magic = utils.readBytes(view, offset, 3);
+	//"ID3"
+	return id3Magic[0] === 73 && id3Magic[1] === 68 && id3Magic[2] === 51;
+}
+
+function getUint28(view, offset) {
+	var sizeBytes = utils.readBytes(view, offset, 4);
+	var mask = 0xfffffff;
+	return ((sizeBytes[0] & mask) << 21) |
+		((sizeBytes[1] & mask) << 14) |
+		((sizeBytes[2] & mask) << 7) |
+		(sizeBytes[3] & mask);
+}
+
+//http://id3.org/id3v2.3.0
+//http://id3.org/id3v2.4.0-structure
+//http://id3.org/id3v2.4.0-frames
+module.exports = function(buffer) {
+	var view = utils.createView(buffer);
+	if (!checkMagicId3(view, 0)) {
+		return null;
+	}
+
+	var offset = 3;
+	//var majorVersion = view.getUint8(offset);
+	offset += 2;
+	var flags = view.getUint8(offset);
+	offset++;
+	var size = getUint28(view, offset);
+	offset += 4;
+
+	var extendedHeader = (flags & 128) > 0;
+
+	if (extendedHeader) {
+		offset += getUint28(view, offset);
+	}
+
+	function readFrame(offset) {
+		try {
+			var id = utils.readAscii(view, offset, 4);
+			var size = getUint28(view, offset + 4);
+			offset += 10; //+2 more for flags we don't care about
+
+			if (id[0] !== 'T') {
+				return {
+					id: id,
+					size: size + 10
+				};
+			}
+
+			var encoding = view.getUint8(offset),
+				data = '';
+
+			if (encoding <= 3) {
+				offset++;
+				if (encoding === 3) {
+					//UTF8 - null terminated
+					data = utils.readUtf8(view, offset, size - 1);
+				} else {
+					//ISO-8859-1, UTF-16, UTF-16BE
+					//UTF-16 and UTF-16BE are $FF $00 terminated
+					//ISO is null terminated
+
+					//screw these encodings, read it as ascii
+					data = utils.readAscii(view, offset, size - 1);
+				}
+			} else {
+				//no encoding info, read it as ascii
+				data = utils.readAscii(view, offset, size);
+			}
+
+			//id3v2.4 is supposed to have encoding terminations, but sometimes
+			//they don't? meh.
+			data = utils.trimNull(data);
+
+			return {
+				id: id,
+				size: size + 10,
+				content: data
+			};
+		} catch (e) {
+			return null;
+		}
+	}
+
+	var idMap = {
+		TALB: 'album',
+		TCOM: 'composer',
+		TIT1: 'title',
+		TIT2: 'title',
+		TPE1: 'artist',
+		TRCK: 'track',
+		TSSE: 'encoder',
+		TDRC: 'year',
+		TCON: 'genre'
+	};
+
+	var endOfTags = offset + size,
+		frames = {};
+	while (offset < endOfTags) {
+		var frame = readFrame(offset);
+		if (!frame) {
+			break;
+		}
+
+		offset += frame.size;
+		if (!frame.content) {
+			continue;
+		}
+		var id = idMap[frame.id] || frame.id;
+		if (id === 'TXXX') {
+			var nullByte = frame.content.indexOf('\u0000');
+			id = frame.content.substring(0, nullByte);
+			frames[id] = frame.content.substring(nullByte + 1);
+		} else {
+			frames[id] = frames[frame.id] = frame.content;
+		}
+	}
+
+	return frames;
+};