diff --git a/daemon/codec.c b/daemon/codec.c
index 43b08b586..e00a69570 100644
--- a/daemon/codec.c
+++ b/daemon/codec.c
@@ -419,7 +419,7 @@ static void __make_transcoder(struct codec_handler *handler, struct rtp_payload_
 	// don't reset handler if it already matches what we want
 	if (!handler->transcoder)
 		goto reset;
-	if (!rtp_payload_type_eq(dest, &handler->dest_pt))
+	if (!rtp_payload_type_eq_exact(dest, &handler->dest_pt))
 		goto reset;
 	if (handler->handler_func != handler_func_transcode)
 		goto reset;
@@ -707,7 +707,7 @@ static struct codec_handler *__get_pt_handler(struct call_media *receiver, struc
 	handler = codec_handler_lookup(receiver->codec_handlers, pt->payload_type, sink);
 	if (handler) {
 		// make sure existing handler matches this PT
-		if (!rtp_payload_type_eq(pt, &handler->source_pt)) {
+		if (!rtp_payload_type_eq_exact(pt, &handler->source_pt)) {
 			ilogs(codec, LOG_DEBUG, "Resetting codec handler for PT %i", pt->payload_type);
 			g_hash_table_remove(receiver->codec_handlers, handler);
 			__handler_shutdown(handler);
@@ -1069,7 +1069,7 @@ bool codec_handlers_update(struct call_media *receiver, struct call_media *sink,
 			sink_pt = g_hash_table_lookup(sink->codecs.codecs,
 					GINT_TO_POINTER(pt->payload_type));
 			// is it actually the same?
-			if (sink_pt && !rtp_payload_type_eq(pt, sink_pt))
+			if (sink_pt && !rtp_payload_type_eq_compat(pt, sink_pt))
 				sink_pt = NULL;
 		}
 
@@ -4894,7 +4894,7 @@ bool codec_store_is_full_answer(const struct codec_store *src, const struct code
 		const struct rtp_payload_type *src_pt = l->data;
 		const struct rtp_payload_type *dst_pt = g_hash_table_lookup(dst->codecs,
 				GINT_TO_POINTER(src_pt->payload_type));
-		if (!dst_pt || !rtp_payload_type_eq(src_pt, dst_pt)) {
+		if (!dst_pt || !rtp_payload_type_eq_compat(src_pt, dst_pt)) {
 			ilogs(codec, LOG_DEBUG, "Source codec " STR_FORMAT " is not present in the answer",
 					STR_FMT(&src_pt->encoding_with_params));
 			return false;
diff --git a/daemon/media_player.c b/daemon/media_player.c
index f2d3ae340..d103ac3e2 100644
--- a/daemon/media_player.c
+++ b/daemon/media_player.c
@@ -308,8 +308,8 @@ found:
 
 	// if we already have a handler, see if anything needs changing
 	if (mp->handler) {
-		if (!rtp_payload_type_eq(&mp->handler->dest_pt, dst_pt)
-				|| !rtp_payload_type_eq(&mp->handler->source_pt, src_pt))
+		if (!rtp_payload_type_eq_exact(&mp->handler->dest_pt, dst_pt)
+				|| !rtp_payload_type_eq_exact(&mp->handler->source_pt, src_pt))
 		{
 			ilog(LOG_DEBUG, "Resetting codec handler for media player");
 			codec_handler_free(&mp->handler);
diff --git a/lib/codeclib.h b/lib/codeclib.h
index d8b781260..3b9e3a05d 100644
--- a/lib/codeclib.h
+++ b/lib/codeclib.h
@@ -6,6 +6,7 @@ struct codec_def_s;
 struct packet_sequencer_s;
 typedef struct codec_def_s codec_def_t;
 typedef struct packet_sequencer_s packet_sequencer_t;
+struct rtp_payload_type;
 
 enum media_type {
 	MT_UNKNOWN = 0,
@@ -35,6 +36,12 @@ INLINE enum media_type codec_get_type(const str *type) {
 }
 
 
+// 0:  exact match
+// 1:  a is compatible with b (not necessarily the other way around)
+// -1: a is not compatible with b
+typedef int format_cmp_f(const struct rtp_payload_type *a, const struct rtp_payload_type *b);
+
+
 #ifndef WITHOUT_CODECLIB
 
 
@@ -77,7 +84,7 @@ typedef int packetizer_f(AVPacket *, GString *, str *, encoder_t *);
 typedef void format_init_f(struct rtp_payload_type *);
 typedef void set_enc_options_f(encoder_t *, const str *);
 typedef void set_dec_options_f(decoder_t *, const str *);
-typedef int format_cmp_f(const struct rtp_payload_type *, const struct rtp_payload_type *);
+
 typedef int format_parse_f(struct rtp_codec_format *, const str *fmtp);
 
 
@@ -389,7 +396,6 @@ INLINE int decoder_event(decoder_t *dec, enum codec_event event, void *ptr) {
 
 #else
 
-typedef int format_cmp_f(const void *, const void *);
 
 // stubs
 struct codec_def_s {
diff --git a/lib/rtplib.c b/lib/rtplib.c
index 96de9ae54..fbfda7a15 100644
--- a/lib/rtplib.c
+++ b/lib/rtplib.c
@@ -144,28 +144,53 @@ const struct rtp_payload_type *rtp_get_rfc_codec(const str *codec) {
 	return NULL;
 }
 
-bool rtp_payload_type_eq(const struct rtp_payload_type *a, const struct rtp_payload_type *b) {
-	if (!rtp_payload_type_eq_nf(a, b))
+// helper function: matches only basic params, without matching payload type number
+static bool rtp_payload_type_fmt_eq_nf(const struct rtp_payload_type *a, const struct rtp_payload_type *b) {
+	if (a->clock_rate != b->clock_rate)
+		return false;
+	if (a->channels != b->channels)
 		return false;
+	if (str_casecmp_str(&a->encoding, &b->encoding))
+		return false;
+	return true;
+}
+
+// matches basic params and format params, but not payload type number
+// returns matching val as per format_cmp_f
+int rtp_payload_type_fmt_eq(const struct rtp_payload_type *a, const struct rtp_payload_type *b) {
+	if (!rtp_payload_type_fmt_eq_nf(a, b))
+		return -1;
 	if (a->codec_def && a->codec_def == b->codec_def) {
 		if (a->codec_def->format_cmp)
-			return a->codec_def->format_cmp(a, b) == 0;
+			return a->codec_def->format_cmp(a, b);
 	}
 	if (!a->codec_def) // ignore format of codecs we don't know
-		return true;
+		return 0;
 	if (str_cmp_str(&a->format_parameters, &b->format_parameters))
-		return false;
-	return true;
+		return -1;
+	return 0;
+}
+bool rtp_payload_type_fmt_eq_exact(const struct rtp_payload_type *a, const struct rtp_payload_type *b) {
+	return rtp_payload_type_fmt_eq(a, b) == 0;
+}
+bool rtp_payload_type_fmt_eq_compat(const struct rtp_payload_type *a, const struct rtp_payload_type *b) {
+	return rtp_payload_type_fmt_eq(a, b) >= 0;
 }
 
-bool rtp_payload_type_eq_nf(const struct rtp_payload_type *a, const struct rtp_payload_type *b) {
+bool rtp_payload_type_eq_exact(const struct rtp_payload_type *a, const struct rtp_payload_type *b) {
 	if (a->payload_type != b->payload_type)
 		return false;
-	if (a->clock_rate != b->clock_rate)
-		return false;
-	if (a->channels != b->channels)
+	return rtp_payload_type_fmt_eq(a, b) == 0;
+}
+bool rtp_payload_type_eq_compat(const struct rtp_payload_type *a, const struct rtp_payload_type *b) {
+	if (a->payload_type != b->payload_type)
 		return false;
-	if (str_casecmp_str(&a->encoding, &b->encoding))
+	return rtp_payload_type_fmt_eq(a, b) >= 0;
+}
+
+// same as rtp_payload_type_fmt_eq_nf plus matching payload type number
+bool rtp_payload_type_eq_nf(const struct rtp_payload_type *a, const struct rtp_payload_type *b) {
+	if (a->payload_type != b->payload_type)
 		return false;
-	return true;
+	return rtp_payload_type_fmt_eq_nf(a, b);
 }
diff --git a/lib/rtplib.h b/lib/rtplib.h
index d40076b02..0b76e785c 100644
--- a/lib/rtplib.h
+++ b/lib/rtplib.h
@@ -75,8 +75,16 @@ int rtp_padding(const struct rtp_header *header, str *payload);
 const struct rtp_payload_type *rtp_get_rfc_payload_type(unsigned int type);
 const struct rtp_payload_type *rtp_get_rfc_codec(const str *codec);
 
-bool rtp_payload_type_eq(const struct rtp_payload_type *, const struct rtp_payload_type *);
+// if not `exact` then also returns true if `a` is compatible with `b`
+// matches all params
+bool rtp_payload_type_eq_exact(const struct rtp_payload_type *a, const struct rtp_payload_type *b);
+bool rtp_payload_type_eq_compat(const struct rtp_payload_type *a, const struct rtp_payload_type *b);
+// matches only basic params and payload type number
 bool rtp_payload_type_eq_nf(const struct rtp_payload_type *, const struct rtp_payload_type *);
+// matches all params except payload type number
+int rtp_payload_type_fmt_eq(const struct rtp_payload_type *a, const struct rtp_payload_type *b);
+bool rtp_payload_type_fmt_eq_exact(const struct rtp_payload_type *a, const struct rtp_payload_type *b);
+bool rtp_payload_type_fmt_eq_compat(const struct rtp_payload_type *a, const struct rtp_payload_type *b);
 
 
 #endif