feat: Implement InDTX for Encoder

encoder.go

@@ -25,6 +25,12 @@ bridge_encoder_get_dtx(OpusEncoder *st, opus_int32 *dtx)
 	return opus_encoder_ctl(st, OPUS_GET_DTX(dtx));
 }
 
+int
+bridge_encoder_get_in_dtx(OpusEncoder *st, opus_int32 *in_dtx)
+{
+	return opus_encoder_ctl(st, OPUS_GET_IN_DTX(in_dtx));
+}
+
 int
 bridge_encoder_get_sample_rate(OpusEncoder *st, opus_int32 *sample_rate)
 {
@@ -239,6 +245,17 @@ func (enc *Encoder) DTX() (bool, error) {
 	return dtx != 0, nil
 }
 
+// InDTX returns whether the last encoded frame was either a comfort noise update
+// during DTX or not encoded because of DTX.
+func (enc *Encoder) InDTX() (bool, error) {
+	var inDTX C.opus_int32
+	res := C.bridge_encoder_get_in_dtx(enc.p, &inDTX)
+	if res != C.OPUS_OK {
+		return false, Error(res)
+	}
+	return inDTX != 0, nil
+}
+
 // SampleRate returns the encoder sample rate in Hz.
 func (enc *Encoder) SampleRate() (int, error) {
 	var sr C.opus_int32

encoder_test.go

@@ -50,6 +50,50 @@ func TestEncoderDTX(t *testing.T) {
 	}
 }
 
+func TestEncoderInDTX(t *testing.T) {
+	// Create bogus input sound
+	const G4 = 391.995
+	const SAMPLE_RATE = 48000
+	const FRAME_SIZE_MS = 60
+	const FRAME_SIZE = SAMPLE_RATE * FRAME_SIZE_MS / 1000
+	pcm := make([]int16, FRAME_SIZE)
+	silentPCM := make([]int16, FRAME_SIZE)
+	out := make([]byte, FRAME_SIZE*4)
+	addSine(pcm, SAMPLE_RATE, G4)
+
+	vals := []bool{true, false}
+	for _, dtx := range vals {
+		enc, err := NewEncoder(SAMPLE_RATE, 1, AppVoIP)
+		if err != nil || enc == nil {
+			t.Fatalf("Error creating new encoder: %v", err)
+		}
+		enc.SetDTX(dtx)
+		if _, err = enc.Encode(pcm, out); err != nil {
+			t.Fatalf("Error encoding non-silent frame: %v", err)
+		}
+		gotDTX, err := enc.InDTX()
+		if err != nil {
+			t.Fatalf("Error getting in DTX (%t): %v", dtx, err)
+		}
+		if gotDTX {
+			t.Fatalf("Error get in dtx: expect in dtx=false, got=true")
+		}
+		// Encode a few frames to let DTX kick in
+		for i := 0; i < 5; i++ {
+			if _, err = enc.Encode(silentPCM, out); err != nil {
+				t.Fatalf("Error encoding silent frame: %v", err)
+			}
+		}
+		gotDTX, err = enc.InDTX()
+		if err != nil {
+			t.Fatalf("Error getting in DTX (%t): %v", dtx, err)
+		}
+		if gotDTX != dtx {
+			t.Errorf("Error set dtx: expect in dtx=%v, got in dtx=%v", dtx, gotDTX)
+		}
+	}
+}
+
 func TestEncoderSampleRate(t *testing.T) {
 	sample_rates := []int{8000, 12000, 16000, 24000, 48000}
 	for _, f := range sample_rates {