MT#55283 improve asymmetric codec logic

Instead of always blindly picking the matching supp codec for the
receiver codec, pick it only if there is no appropriate sink supp codec,
or both are compatible (which implies a payload type mismatch).

Closes #2084

Change-Id: Ie401db500a038f60f3b4286e2067f90674c611df

daemon/codec.c

@@ -1598,7 +1598,7 @@ void __codec_handlers_update(struct call_media *receiver, struct call_media *sin
 		if (!sink_pt) {
 			// no matching/identical output codec. maybe we have the same output codec,
 			// but with a different payload type or a different format?
-			if (!a.allow_asymmetric || pt->for_transcoding)
+			if (!a.allow_asymmetric || pt->for_transcoding || pt->codec_def->supplemental)
 				sink_pt = codec_store_find_compatible(&sink->codecs, pt);
 			else
 				sink_pt = pt;
@@ -1648,17 +1648,15 @@ void __codec_handlers_update(struct call_media *receiver, struct call_media *sin
 
 sink_pt_fixed:;
 		// we have found a usable output codec. gather matching output supp codecs
-		rtp_payload_type *sink_dtmf_pt = NULL;
-		rtp_payload_type *sink_cn_pt = NULL;
-		if (!a.allow_asymmetric) {
-			sink_dtmf_pt = __supp_payload_type(supplemental_sinks,
-					sink_pt->clock_rate, "telephone-event");
-			sink_cn_pt = __supp_payload_type(supplemental_sinks,
-					sink_pt->clock_rate, "CN");
-		}
-		else {
-			sink_dtmf_pt = recv_dtmf_pt;
-			sink_cn_pt = recv_cn_pt;
+		rtp_payload_type *sink_dtmf_pt = __supp_payload_type(supplemental_sinks,
+				sink_pt->clock_rate, "telephone-event");
+		rtp_payload_type *sink_cn_pt = __supp_payload_type(supplemental_sinks,
+				sink_pt->clock_rate, "CN");
+		if (a.allow_asymmetric) {
+			if (!sink_dtmf_pt || (recv_dtmf_pt && !rtp_payload_type_fmt_cmp(sink_dtmf_pt, recv_dtmf_pt)))
+				sink_dtmf_pt = recv_dtmf_pt;
+			if (!sink_cn_pt || (recv_cn_pt && !rtp_payload_type_fmt_cmp(sink_cn_pt, recv_cn_pt)))
+				sink_cn_pt = recv_cn_pt;
 		}
 		rtp_payload_type *real_sink_dtmf_pt = NULL; // for DTMF delay