sub.ass now returns as bytes

I was getting some UnicodeDecoding errors while I was processing some input. Since ffmpeg docs do not promise char* ass contains UTF-8 strings, I thought it was better to have @Property ass return bytes instead of str.

av/subtitles/subtitle.pyi

@@ -33,4 +33,4 @@ class TextSubtitle(Subtitle):
 
 class AssSubtitle(Subtitle):
     type: Literal[b"ass"]
-    ass: str
+    ass: bytes

av/subtitles/subtitle.pyx

@@ -1,6 +1,10 @@
 from cpython cimport PyBuffer_FillInfo
 
 
+cdef extern from "Python.h":
+    bytes PyBytes_FromString(char*)
+
+
 cdef class SubtitleProxy:
     def __dealloc__(self):
         lib.avsubtitle_free(&self.struct)
@@ -153,4 +157,6 @@ cdef class AssSubtitle(Subtitle):
 
     @property
     def ass(self):
-        return self.ptr.ass
+        if self.ptr.ass is not NULL:
+            return PyBytes_FromString(self.ptr.ass)
+        return b""

tests/test_subtitles.py

@@ -24,7 +24,7 @@ def test_movtext(self):
         sub = subset[0]
         self.assertIsInstance(sub, AssSubtitle)
         self.assertEqual(sub.type, b"ass")
-        self.assertEqual(sub.ass, "0,0,Default,,0,0,0,,- Test 1.\\N- Test 2.")
+        self.assertEqual(sub.ass, b"0,0,Default,,0,0,0,,- Test 1.\\N- Test 2.")
 
     def test_vobsub(self):
         path = fate_suite("sub/vobsub.sub")