Add support for aac format

index.d.ts

@@ -99,7 +99,8 @@ declare namespace fileType {
 		| 'lnk'
 		| 'alias'
 		| 'voc'
-		| 'ac3';
+		| 'ac3'
+		| 'aac';
 
 	interface FileTypeResult {
 		/**

index.js

@@ -38,6 +38,17 @@ const fileType = input => {
 
 	const checkString = (header, options) => check(stringToBytes(header), options);
 
+	/**
+	 * Specialized function to read ID3 payload length
+	 * @param buf Buffer
+	 * @param off offset in buffer
+	 * @returns {number} ID3 payload length
+	 */
+	function readUINT32SYNCSAFE(buf, off) {
+		return (buf[off + 3] & 0x7F) | ((buf[off + 2]) << 7) |
+			((buf[off + 1]) << 14) | ((buf[off]) << 21);
+	}
+
 	if (check([0xFF, 0xD8, 0xFF])) {
 		return {
 			ext: 'jpg',
@@ -409,46 +420,71 @@ const fileType = input => {
 		};
 	}
 
-	// Check for MPEG header at different starting offsets
+	let flagId3 = false;
+
 	for (let start = 0; start < 2 && start < (buffer.length - 16); start++) {
-		if (
-			check([0x49, 0x44, 0x33], {offset: start}) || // ID3 header
-			check([0xFF, 0xE2], {offset: start, mask: [0xFF, 0xE6]}) // MPEG 1 or 2 Layer 3 header
-		) {
-			return {
-				ext: 'mp3',
-				mime: 'audio/mpeg'
-			};
+		// Check for ID3 header
+		if (buffer.length >= start + 10 && checkString('ID3', {offset: start})) {
+			const id3Len = readUINT32SYNCSAFE(buffer, start + 6);
+			start += (10 + id3Len - 1); // Skip ID3 header
+			flagId3 = true;
+			continue;
 		}
 
-		if (
-			check([0xFF, 0xE4], {offset: start, mask: [0xFF, 0xE6]}) // MPEG 1 or 2 Layer 2 header
-		) {
-			return {
-				ext: 'mp2',
-				mime: 'audio/mpeg'
-			};
-		}
+		// Check MPEG 1 or 2 Layer 3 header, or 'layer 0' for ADTS (MPEG sync-word 0xFFE)
+		if (buffer.length >= start + 2 && check([0xFF, 0xE0], {offset: start, mask: [0xFF, 0xE0]})) {
+			// Check for ADTS header (last bit of sync-word 0xFFF & layer=0)
+			if (check([0x10], {offset: start + 1, mask: [0x16]})) {
+				// Check for (ADTS) MPEG-2
+				if (check([0x08], {offset: start + 1, mask: [0x08]})) {
+					return {
+						ext: 'aac',
+						mime: 'audio/aac'
+					};
+				}
 
-		if (
-			check([0xFF, 0xF8], {offset: start, mask: [0xFF, 0xFC]}) // MPEG 2 layer 0 using ADTS
-		) {
-			return {
-				ext: 'mp2',
-				mime: 'audio/mpeg'
-			};
-		}
+				// Must be (ADTS) MPEG-4
+				return {
+					ext: 'aac',
+					mime: 'audio/aac'
+				};
+			}
 
-		if (
-			check([0xFF, 0xF0], {offset: start, mask: [0xFF, 0xFC]}) // MPEG 4 layer 0 using ADTS
-		) {
-			return {
-				ext: 'mp4',
-				mime: 'audio/mpeg'
-			};
+			// MPEG 1 or 2 Layer 3 header
+			// Check for MPEG layer 3
+			if (check([0x02], {offset: start + 1, mask: [0x06]})) {
+				return {
+					ext: 'mp3',
+					mime: 'audio/mpeg'
+				};
+			}
+
+			// Check for MPEG layer 2
+			if (check([0x04], {offset: start + 1, mask: [0x06]})) {
+				return {
+					ext: 'mp2',
+					mime: 'audio/mpeg'
+				};
+			}
+
+			// Check for MPEG layer 1
+			if (check([0x06], {offset: start + 1, mask: [0x06]})) {
+				return {
+					ext: 'mp1',
+					mime: 'audio/mpeg'
+				};
+			}
 		}
 	}
 
+	if (flagId3) {
+		// Guess it is MP3 if only an ID3 tag header is found
+		return {
+			ext: 'mp3',
+			mime: 'audio/mpeg'
+		};
+	}
+
 	if (
 		check([0x66, 0x74, 0x79, 0x70, 0x4D, 0x34, 0x41], {offset: 4})
 	) {

readme.md

@@ -221,6 +221,7 @@ Type: [`stream.Readable`](https://nodejs.org/api/stream.html#stream_class_stream
 - [`alias`](https://en.wikipedia.org/wiki/Alias_%28Mac_OS%29) - macOS Alias file
 - [`voc`](https://wiki.multimedia.cx/index.php/Creative_Voice) - Creative Voice File
 - [`ac3`](https://www.atsc.org/standard/a522012-digital-audio-compression-ac-3-e-ac-3-standard-12172012/) - ATSC A/52 Audio File
+- [`aac`](https://en.wikipedia.org/wiki/Advanced_Audio_Coding) - Advanced Audio Coding
 
 *SVG isn't included as it requires the whole file to be read, but you can get it [here](https://github.com/sindresorhus/is-svg).*
 

test.js

@@ -108,7 +108,9 @@ const types = [
 	'lnk',
 	'alias',
 	'voc',
-	'ac3'
+	'ac3',
+	'pcap',
+	'aac'
 ];
 
 // Define an entry here only if the fixture has a different
@@ -137,8 +139,7 @@ const names = {
 	],
 	mp2: [
 		'fixture',
-		'fixture-mpa',
-		'fixture-faac-adts'
+		'fixture-mpa'
 	],
 	mp3: [
 		'fixture',
@@ -153,8 +154,7 @@ const names = {
 		'fixture-isomv2',
 		'fixture-mp4v2',
 		'fixture-m4v',
-		'fixture-dash',
-		'fixture-aac-adts'
+		'fixture-dash'
 	],
 	tif: [
 		'fixture-big-endian',
@@ -199,6 +199,11 @@ const names = {
 	tar: [
 		'fixture',
 		'fixture-v7'
+	],
+	aac: [
+		'fixture-adts-mpeg4',
+		'fixture-adts-mpeg4-2',
+		'fixture-adts-mpeg2'
 	]
 };
 
@@ -257,13 +262,15 @@ for (const type of types) {
 	}
 }
 
-test('.stream() method - empty stream', async t => {
-	const emptyStream = fs.createReadStream('/dev/null');
-	await t.throwsAsync(
-		fileType.stream(emptyStream),
-		/Expected the `input` argument to be of type `Uint8Array` /
-	);
-});
+if (process.platform !== 'win32') {
+	test('.stream() method - empty stream', async t => {
+		const emptyStream = fs.createReadStream('/dev/null');
+		await t.throwsAsync(
+			fileType.stream(emptyStream),
+			/Expected the `input` argument to be of type `Uint8Array` /
+		);
+	});
+}
 
 test('fileType.minimumBytes', t => {
 	t.true(fileType.minimumBytes > 4000);