fix(format/stream): access fields directly

src/format/stream/stream.rs

@@ -89,7 +89,7 @@ impl<'a> Stream<'a> {
 	}
 
 	pub fn frame_rate(&self) -> Rational {
-		unsafe { Rational::from(av_stream_get_r_frame_rate(self.as_ptr())) }
+		unsafe { Rational::from((*self.as_ptr()).r_frame_rate) }
 	}
 
 	pub fn avg_frame_rate(&self) -> Rational {

src/format/stream/stream_mut.rs

@@ -34,7 +34,7 @@ impl<'a> StreamMut<'a> {
 
 	pub fn set_rate<R: Into<Rational>>(&mut self, value: R) {
 		unsafe {
-			av_stream_set_r_frame_rate(self.as_mut_ptr(), value.into().into());
+			(*self.as_mut_ptr()).r_frame_rate = value.into().into();
 		}
 	}