codec/parameters: impl AsRef for all codec::Context wrappers

src/codec/encoder/subtitle.rs

@@ -6,7 +6,7 @@ use ffi::*;
 
 use super::Encoder as Super;
 use ::{Error, Dictionary};
-use codec::traits;
+use codec::{traits, Context};
 
 pub struct Subtitle(pub Super);
 
@@ -68,6 +68,12 @@ impl DerefMut for Subtitle {
 	}
 }
 
+impl AsRef<Context> for Subtitle {
+	fn as_ref(&self) -> &Context {
+		&self
+	}
+}
+
 pub struct Encoder(pub Subtitle);
 
 impl Encoder {
@@ -88,3 +94,9 @@ impl Deref for Encoder {
 		&self.0
 	}
 }
+
+impl AsRef<Context> for Encoder {
+	fn as_ref(&self) -> &Context {
+		&self
+	}
+}