Support more mkv files

https://github.com/mifi/lossless-cut/issues/15

package.json

@@ -48,7 +48,7 @@
     "electron-default-menu": "^1.0.0",
     "electron-is-dev": "^0.1.2",
     "execa": "^0.5.0",
-    "file-type": "^3.9.0",
+    "file-type": "git+https://github.com/mifi/file-type.git#92b819e349c0067330b10869c67f5b6ad5937994",
     "jquery": "^3.1.1",
     "keyboardjs": "^2.3.3",
     "lodash": "^4.16.4",

src/ffmpeg.js

@@ -78,7 +78,7 @@ function getFormat(filePath) {
         const formats = (formatsStr || '').split(',');
 
         // ffprobe sometimes returns a list of formats, try to be a bit smarter about it.
-        return readChunk(filePath, 0, 262)
+        return readChunk(filePath, 0, 4100)
           .then((bytes) => {
             const ft = fileType(bytes);
             if (_.includes(formats, (ft || {}).ext)) return ft.ext;