codec: refactor decoder and encoder

src/codec/decoder/conceal.rs

@@ -0,0 +1,10 @@
+use libc::c_int;
+use ffi::*;
+
+bitflags! {
+	flags Conceal: c_int {
+		const CONCEAL_GUESS_MVS   = FF_EC_GUESS_MVS,
+		const CONCEAL_DEBLOCK     = FF_EC_DEBLOCK,
+		const CONCEAL_FAVOR_INTER = FF_EC_FAVOR_INTER,
+	}
+}