rtmp: improve control message compatibility with non-standard cameras (#4909)

* feat: improve RTMP control message compatibility with non-standard cameras

- Add flexible chunk stream ID validation for control messages
- Support common non-standard chunk stream IDs (2,3,4,5,6) used by various cameras
- Maintain backward compatibility with standard RTMP clients
- Fix connection issues with PTZ cameras using chunk stream ID 4

This resolves compatibility issues with IP cameras that don't strictly follow
RTMP spec while maintaining full support for standard RTMP implementations.
Previously, cameras using non-standard chunk stream IDs would fail with
'unexpected chunk stream ID' errors. Now MediaMTX provides nginx-rtmp level
compatibility with real-world camera implementations."

* add tests

* entirely remove control chunk stream ID validation

---------

Co-authored-by: Hyesung.Kim <hyesung.kim@xcath.com>
Co-authored-by: aler9 <46489434+aler9@users.noreply.github.com>

internal/protocols/rtmp/message/msg_acknowledge.go

@@ -12,10 +12,6 @@ type Acknowledge struct {
 }
 
 func (m *Acknowledge) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 4 {
 		return fmt.Errorf("unexpected body size")
 	}

internal/protocols/rtmp/message/msg_set_chunk_size.go

@@ -12,10 +12,6 @@ type SetChunkSize struct {
 }
 
 func (m *SetChunkSize) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 4 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/msg_set_peer_bandwidth.go

@@ -13,10 +13,6 @@ type SetPeerBandwidth struct {
 }
 
 func (m *SetPeerBandwidth) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 5 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/msg_set_window_ack_size.go

@@ -12,10 +12,6 @@ type SetWindowAckSize struct {
 }
 
 func (m *SetWindowAckSize) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 4 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/msg_user_control_ping_request.go

@@ -12,10 +12,6 @@ type UserControlPingRequest struct {
 }
 
 func (m *UserControlPingRequest) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 6 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/msg_user_control_ping_response.go

@@ -12,10 +12,6 @@ type UserControlPingResponse struct {
 }
 
 func (m *UserControlPingResponse) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 6 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/msg_user_control_set_buffer_length.go

@@ -13,10 +13,6 @@ type UserControlSetBufferLength struct {
 }
 
 func (m *UserControlSetBufferLength) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 10 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/msg_user_control_stream_begin.go

@@ -12,10 +12,6 @@ type UserControlStreamBegin struct {
 }
 
 func (m *UserControlStreamBegin) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 6 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/msg_user_control_stream_dry.go

@@ -12,10 +12,6 @@ type UserControlStreamDry struct {
 }
 
 func (m *UserControlStreamDry) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 6 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/msg_user_control_stream_eof.go

@@ -12,10 +12,6 @@ type UserControlStreamEOF struct {
 }
 
 func (m *UserControlStreamEOF) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 6 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/msg_user_control_stream_is_recorded.go

@@ -12,10 +12,6 @@ type UserControlStreamIsRecorded struct {
 }
 
 func (m *UserControlStreamIsRecorded) unmarshal(raw *rawmessage.Message) error {
-	if raw.ChunkStreamID != ControlChunkStreamID {
-		return fmt.Errorf("unexpected chunk stream ID")
-	}
-
 	if len(raw.Body) != 6 {
 		return fmt.Errorf("invalid body size")
 	}

internal/protocols/rtmp/message/reader_test.go

@@ -645,6 +645,22 @@ func TestReader(t *testing.T) {
 	}
 }
 
+func TestReaderNonStandardControlChunkStreamID(t *testing.T) {
+	buf := []byte{
+		0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x06, 0x04,
+		0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x00,
+		0x8a, 0xce,
+	}
+
+	bc := bytecounter.NewReader(bytes.NewReader(buf))
+	r := NewReader(bc, bc, nil)
+	dec, err := r.Read()
+	require.NoError(t, err)
+	require.Equal(t, &UserControlStreamDry{
+		StreamID: 35534,
+	}, dec)
+}
+
 func FuzzReader(f *testing.F) {
 	for _, ca := range readWriterCases {
 		f.Add(ca.enc)