Implemented alternative proposal via SettingEngine

Author: yngrtc

webrtc/src/api/media_engine/mod.rs

@@ -336,17 +336,6 @@ impl MediaEngine {
         codecs.push(codec);
     }
 
-    /// set_multi_codec_negotiation enables or disables the negotiation of multiple codecs.
-    pub fn set_multi_codec_negotiation(&mut self, negotiate_multi_codecs: bool) {
-        self.negotiate_multi_codecs
-            .store(negotiate_multi_codecs, Ordering::SeqCst);
-    }
-
-    /// multi_codec_negotiation returns the current state of the negotiation of multiple codecs.
-    pub fn multi_codec_negotiation(&self) -> bool {
-        self.negotiate_multi_codecs.load(Ordering::SeqCst)
-    }
-
     /// register_codec adds codec to the MediaEngine
     /// These are the list of codecs supported by this PeerConnection.
     /// register_codec is not safe for concurrent use.
@@ -473,6 +462,17 @@ impl MediaEngine {
         }
     }
 
+    /// set_multi_codec_negotiation enables or disables the negotiation of multiple codecs.
+    pub(crate) fn set_multi_codec_negotiation(&self, negotiate_multi_codecs: bool) {
+        self.negotiate_multi_codecs
+            .store(negotiate_multi_codecs, Ordering::SeqCst);
+    }
+
+    /// multi_codec_negotiation returns the current state of the negotiation of multiple codecs.
+    pub(crate) fn multi_codec_negotiation(&self) -> bool {
+        self.negotiate_multi_codecs.load(Ordering::SeqCst)
+    }
+
     pub(crate) async fn get_codec_by_payload(
         &self,
         payload_type: PayloadType,

webrtc/src/api/setting_engine/mod.rs

@@ -99,6 +99,7 @@ pub struct SettingEngine {
     //iceProxyDialer                            :proxy.Dialer,?
     pub(crate) udp_network: UDPNetwork,
     pub(crate) disable_media_engine_copy: bool,
+    pub(crate) disable_media_engine_multiple_codecs: bool,
     pub(crate) srtp_protection_profiles: Vec<SrtpProtectionProfile>,
     pub(crate) receive_mtu: usize,
     pub(crate) mid_generator: Option<Arc<dyn Fn(isize) -> String + Send + Sync>>,
@@ -342,6 +343,16 @@ impl SettingEngine {
         self.disable_media_engine_copy = is_disabled;
     }
 
+    /// disable_media_engine_multiple_codecs disables the MediaEngine negotiating different codecs.
+    /// With the default value multiple media sections in the SDP can each negotiate different
+    /// codecs. This is the new default behvior, because it makes Pion more spec compliant.
+    /// The value of this setting will get copied to every copy of the MediaEngine generated
+    /// for new PeerConnections (assuming DisableMediaEngineCopy is set to false).
+    /// Note: this setting is targeted to be removed in release 4.2.0 (or later).
+    pub fn disable_media_engine_multiple_codecs(&mut self, is_disabled: bool) {
+        self.disable_media_engine_multiple_codecs = is_disabled;
+    }
+
     /// set_receive_mtu sets the size of read buffer that copies incoming packets. This is optional.
     /// Leave this 0 for the default receive_mtu
     pub fn set_receive_mtu(&mut self, receive_mtu: usize) {

webrtc/src/api/setting_engine/setting_engine_test.rs

@@ -269,3 +269,15 @@ async fn test_setting_engine_set_disable_media_engine_copy() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn test_setting_engine_media_engine_and_mtu_flags() -> Result<()> {
+    let mut s = SettingEngine::default();
+
+    s.disable_media_engine_multiple_codecs(true);
+    assert!(s.disable_media_engine_multiple_codecs);
+
+    s.set_receive_mtu(1337);
+    assert_eq!(1337, s.receive_mtu);
+    Ok(())
+}

webrtc/src/peer_connection/peer_connection_internal.rs

@@ -121,10 +121,14 @@ impl PeerConnectionInternal {
             peer_connection_state: Arc::new(AtomicU8::new(RTCPeerConnectionState::New as u8)),
 
             setting_engine: Arc::clone(&api.setting_engine),
-            media_engine: if !api.setting_engine.disable_media_engine_copy {
-                Arc::new(api.media_engine.clone_to())
-            } else {
+            media_engine: if api.setting_engine.disable_media_engine_copy {
                 Arc::clone(&api.media_engine)
+            } else {
+                let cloned_media_engine = Arc::new(api.media_engine.clone_to());
+                cloned_media_engine.set_multi_codec_negotiation(
+                    !api.setting_engine.disable_media_engine_multiple_codecs,
+                );
+                cloned_media_engine
             },
             interceptor,
             stats_interceptor,