From a58fdc70bb67c0848c05598ff93a26c62a1bec6f Mon Sep 17 00:00:00 2001
From: Alex Snyatkov <snyatkov@amazon.com>
Date: Tue, 24 Feb 2026 23:37:31 +0000
Subject: [PATCH] feat: Export GetCodecMap for performance optimization

Allows callers to build codec map once and reuse it instead of
rebuilding on every GetCodecForPayloadType call.
---
 util.go      |  9 +++++----
 util_test.go | 22 ++++++++++++++++++++++
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/util.go b/util.go
index b6f6a98..92c2797 100644
--- a/util.go
+++ b/util.go
@@ -226,7 +226,8 @@ func mergeCodecs(codec Codec, codecs map[uint8]Codec) {
 	codecs[savedCodec.PayloadType] = savedCodec
 }
 
-func (s *SessionDescription) buildCodecMap() map[uint8]Codec { //nolint:cyclop
+// GetCodecMap builds the codec map from the session description.
+func (s *SessionDescription) GetCodecMap() map[uint8]Codec { //nolint:cyclop
 	codecs := map[uint8]Codec{
 		// static codecs that do not require a rtpmap
 		0: {
@@ -326,7 +327,7 @@ func codecsMatch(wanted, got Codec) bool {
 
 // GetCodecForPayloadType scans the SessionDescription for the given payload type and returns the codec.
 func (s *SessionDescription) GetCodecForPayloadType(payloadType uint8) (Codec, error) {
-	codecs := s.buildCodecMap()
+	codecs := s.GetCodecMap()
 
 	codec, ok := codecs[payloadType]
 	if ok {
@@ -337,7 +338,7 @@ func (s *SessionDescription) GetCodecForPayloadType(payloadType uint8) (Codec, e
 }
 
 func (s *SessionDescription) GetCodecsForPayloadTypes(payloadTypes []uint8) ([]Codec, error) {
-	codecs := s.buildCodecMap()
+	codecs := s.GetCodecMap()
 
 	result := make([]Codec, 0, len(payloadTypes))
 	for _, payloadType := range payloadTypes {
@@ -353,7 +354,7 @@ func (s *SessionDescription) GetCodecsForPayloadTypes(payloadTypes []uint8) ([]C
 // GetPayloadTypeForCodec scans the SessionDescription for a codec that matches the provided codec
 // as closely as possible and returns its payload type.
 func (s *SessionDescription) GetPayloadTypeForCodec(wanted Codec) (uint8, error) {
-	codecs := s.buildCodecMap()
+	codecs := s.GetCodecMap()
 
 	for payloadType, codec := range codecs {
 		if codecsMatch(wanted, codec) {
diff --git a/util_test.go b/util_test.go
index 1f1d82c..df8ae61 100644
--- a/util_test.go
+++ b/util_test.go
@@ -521,3 +521,25 @@ func TestLexer_HandleType_SyntaxErrorWhenFnReturnsNil(t *testing.T) {
 	var se syntaxError
 	assert.ErrorAs(t, err, &se)
 }
+
+func BenchmarkGetCodecForPayloadType(b *testing.B) {
+	sd := getTestSessionDescription()
+	payloadTypes := []uint8{120, 121, 126, 97, 98}
+
+	b.Run("WithoutCaching", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			for _, pt := range payloadTypes {
+				_, _ = sd.GetCodecForPayloadType(pt)
+			}
+		}
+	})
+
+	b.Run("WithCaching", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			codecMap := sd.GetCodecMap()
+			for _, pt := range payloadTypes {
+				_ = codecMap[pt]
+			}
+		}
+	})
+}