more wire format specs

src/wire-fmt/mod.rs

@@ -1,7 +1,11 @@
 pub enum SpecialCapability {
-    pub StereoOut = 1,
+    pub Telephone = 1,
-    pub StereoIn = 2,
+    pub Typewriter = 2,
-    pub Telephone = 3,
+    pub IpDce = 3,
-    pub Typewriter = 4,
+    pub EthernetDce = 4,
-    pub IpDce = 5,
+}
+
+pub struct ChannelCapabilities {
+    pub channels: usize
+    pub sample_rate: (u64, Option<u64>),
 }