improved mp3 detection

filetype/types/audio.py

@@ -40,16 +40,25 @@ def __init__(self):
         )
 
     def match(self, buf):
-        return (len(buf) > 2 and
-                ((buf[0] == 0x49 and
-                  buf[1] == 0x44 and
-                  buf[2] == 0x33) or
-                 (buf[0] == 0xFF and
-                  buf[1] == 0xF2) or
-                 (buf[0] == 0xFF and
-                  buf[1] == 0xF3) or
-                 (buf[0] == 0xFF and
-                  buf[1] == 0xFB)))
+        if len(buf) > 2:
+            if (
+                buf[0] == 0x49 and
+                buf[1] == 0x44 and
+                buf[2] == 0x33
+            ):
+                return True
+
+            if buf[0] == 0xFF:
+                if (
+                    buf[1] == 0xE2 or  # MPEG 2.5 with error protection
+                    buf[1] == 0xE3 or  # MPEG 2.5 w/o error protection
+                    buf[1] == 0xF2 or  # MPEG 2 with error protection
+                    buf[1] == 0xF3 or  # MPEG 2 w/o error protection
+                    buf[1] == 0xFA or  # MPEG 1 with error protection
+                    buf[1] == 0xFB     # MPEG 1 w/o error protection
+                ):
+                    return True
+        return False
 
 
 class M4a(Type):