Add support for WebVTT (#658)

core.d.ts

@@ -165,6 +165,7 @@ export type FileExtension =
 	| 'icc'
 	| 'fbx'
 	| 'vsdx'
+	| 'vtt'
 	; // eslint-disable-line semi-style
 
 export type MimeType =
@@ -270,6 +271,7 @@ export type MimeType =
 	| 'audio/x-musepack'
 	| 'text/calendar'
 	| 'text/vcard'
+	| 'text/vtt'
 	| 'model/gltf-binary'
 	| 'application/vnd.tcpdump.pcap'
 	| 'audio/x-dsf' // Non-standard

core.js

@@ -1139,6 +1139,18 @@ export class FileTypeParser {
 			}
 		}
 
+		if (
+			this.checkString('WEBVTT')
+			&&	(
+				// One of LF, CR, tab, space, or end of file must follow "WEBVTT" per the spec (see `fixture/fixture-vtt-*.vtt` for examples). Note that `\0` is technically the null character (there is no such thing as an EOF character). However, checking for `\0` gives us the same result as checking for the end of the stream.
+				(['\n', '\r', '\t', ' ', '\0'].some(char7 => this.checkString(char7, {offset: 6}))))
+		) {
+			return {
+				ext: 'vtt',
+				mime: 'text/vtt',
+			};
+		}
+
 		// -- 8-byte signatures --
 
 		if (this.check([0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A])) {

fixture/fixture-vtt-eof.vtt

@@ -0,0 +1 @@
+WEBVTT

fixture/fixture-vtt-linebreak.vtt

@@ -0,0 +1,4 @@
+WEBVTT
+
+00:11.000 --> 00:13.000
+<v Speaker Name>Test WEBVTT prefix followed by a line break

fixture/fixture-vtt-space.vtt

@@ -0,0 +1,2 @@
+WEBVTT 00:11.000 --> 00:13.000
+<v Speaker Name>Test WEBVTT prefix followed by a space

fixture/fixture-vtt-tab.vtt

@@ -0,0 +1,2 @@
+WEBVTT	00:11.000 --> 00:13.000
+<v Speaker Name>Test WEBVTT prefix followed by a tab

package.json

@@ -215,7 +215,8 @@
 		"avro",
 		"icc",
 		"fbx",
-		"vsdx"
+		"vsdx",
+		"vtt"
 	],
 	"dependencies": {
 		"get-stream": "^9.0.1",

readme.md

@@ -507,6 +507,7 @@ console.log(fileType);
 - [`vcf`](https://en.wikipedia.org/wiki/VCard) - vCard
 - [`voc`](https://wiki.multimedia.cx/index.php/Creative_Voice) - Creative Voice File
 - [`vsdx`](https://en.wikipedia.org/wiki/Microsoft_Visio) - Microsoft Visio File
+- [`vtt`](https://en.wikipedia.org/wiki/WebVTT) - WebVTT File (for video captions)
 - [`wasm`](https://en.wikipedia.org/wiki/WebAssembly) - WebAssembly intermediate compiled format
 - [`wav`](https://en.wikipedia.org/wiki/WAV) - Waveform Audio file
 - [`webm`](https://en.wikipedia.org/wiki/WebM) - Web video file

supported.js

@@ -152,6 +152,7 @@ export const extensions = [
 	'icc',
 	'fbx',
 	'vsdx',
+	'vtt',
 ];
 
 export const mimeTypes = [
@@ -257,6 +258,7 @@ export const mimeTypes = [
 	'audio/x-musepack',
 	'text/calendar',
 	'text/vcard',
+	'text/vtt',
 	'model/gltf-binary',
 	'application/vnd.tcpdump.pcap',
 	'audio/x-dsf', // Non-standard

test.js

@@ -261,6 +261,12 @@ const names = {
 		'fixture-vsdx',
 		'fixture-vstx',
 	],
+	vtt: [
+		'fixture-vtt-linebreak',
+		'fixture-vtt-space',
+		'fixture-vtt-tab',
+		'fixture-vtt-eof',
+	],
 };
 
 // Define an entry here only if the file type has potential