4 files changed, 22 insertions, 5 deletions
diff --git a/servers/audio/audio_stream.cpp b/servers/audio/audio_stream.cpp
index 7de0695e8c..02a0bed964 100644
--- a/servers/audio/audio_stream.cpp
+++ b/servers/audio/audio_stream.cpp
@@ -136,16 +136,20 @@ void AudioStreamPlaybackMicrophone::_mix_internal(AudioFrame *p_buffer, int p_fr
 
 	Vector<int32_t> buf = AudioDriver::get_singleton()->get_input_buffer();
 	unsigned int input_size = AudioDriver::get_singleton()->get_input_size();
+	int mix_rate = AudioDriver::get_singleton()->get_mix_rate();
+	int playback_delay = MIN(((50 * mix_rate) / 1000) * 2, buf.size() >> 1);
+#ifdef DEBUG_ENABLED
+	unsigned int input_position = AudioDriver::get_singleton()->get_input_position();
+#endif
 
-	// p_frames is multiplied by two since an AudioFrame is stereo
-	if ((p_frames + MICROPHONE_PLAYBACK_DELAY * 2) > input_size) {
+	if (playback_delay > input_size) {
 		for (int i = 0; i < p_frames; i++) {
 			p_buffer[i] = AudioFrame(0.0f, 0.0f);
 		}
 		input_ofs = 0;
 	} else {
 		for (int i = 0; i < p_frames; i++) {
-			if (input_size >= input_ofs) {
+			if (input_size > input_ofs) {
 				float l = (buf[input_ofs++] >> 16) / 32768.f;
 				if (input_ofs >= buf.size()) {
 					input_ofs = 0;
@@ -162,6 +166,12 @@ void AudioStreamPlaybackMicrophone::_mix_internal(AudioFrame *p_buffer, int p_fr
 		}
 	}
 
+#ifdef DEBUG_ENABLED
+	if (input_ofs > input_position && (input_ofs - input_position) < (p_frames * 2)) {
+		print_verbose(String(get_class_name()) + " buffer underrun: input_position=" + itos(input_position) + " input_ofs=" + itos(input_ofs) + " input_size=" + itos(input_size));
+	}
+#endif
+
 	AudioDriver::get_singleton()->unlock();
 }
 
diff --git a/servers/audio/audio_stream.h b/servers/audio/audio_stream.h
index 2740f86d55..f6ed45cc9c 100644
--- a/servers/audio/audio_stream.h
+++ b/servers/audio/audio_stream.h
@@ -122,8 +122,6 @@ class AudioStreamPlaybackMicrophone : public AudioStreamPlaybackResampled {
 	GDCLASS(AudioStreamPlaybackMicrophone, AudioStreamPlayback)
 	friend class AudioStreamMicrophone;
 
-	static const int MICROPHONE_PLAYBACK_DELAY = 256;
-
 	bool active;
 	unsigned int input_ofs;
 
diff --git a/servers/audio_server.cpp b/servers/audio_server.cpp
index d36057b465..37454d9253 100644
--- a/servers/audio_server.cpp
+++ b/servers/audio_server.cpp
@@ -80,6 +80,14 @@ double AudioDriver::get_mix_time() const {
 	return total;
 }
 
+void AudioDriver::input_buffer_init(int driver_buffer_frames) {
+
+	const int input_buffer_channels = 2;
+	input_buffer.resize(driver_buffer_frames * input_buffer_channels * 4);
+	input_position = 0;
+	input_size = 0;
+}
+
 void AudioDriver::input_buffer_write(int32_t sample) {
 
 	input_buffer.write[input_position++] = sample;
diff --git a/servers/audio_server.h b/servers/audio_server.h
index ba6569eb38..b12ca6e589 100644
--- a/servers/audio_server.h
+++ b/servers/audio_server.h
@@ -59,6 +59,7 @@ protected:
 
 	void audio_server_process(int p_frames, int32_t *p_buffer, bool p_update_mix_time = true);
 	void update_mix_time(int p_frames);
+	void input_buffer_init(int driver_buffer_frames);
 	void input_buffer_write(int32_t sample);
 
 #ifdef DEBUG_ENABLED