text: /*************************************************************************/
  /*  audio_stream_generator.cpp                                           */
  /*************************************************************************/
  /*                       This file is part of:                           */
  /*                           GODOT ENGINE                                */
  /*                      https://godotengine.org                          */
  /*************************************************************************/
  /* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
  /* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
  /*                                                                       */
  /* Permission is hereby granted, free of charge, to any person obtaining */
  /* a copy of this software and associated documentation files (the       */
  /* "Software"), to deal in the Software without restriction, including   */
  /* without limitation the rights to use, copy, modify, merge, publish,   */
  /* distribute, sublicense, and/or sell copies of the Software, and to    */
  /* permit persons to whom the Software is furnished to do so, subject to */
  /* the following conditions:                                             */
  /*                                                                       */
  /* The above copyright notice and this permission notice shall be        */
  /* included in all copies or substantial portions of the Software.       */
  /*                                                                       */
  /* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
  /* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
  /* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
  /* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
  /* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
  /* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
  /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
  /*************************************************************************/
  
  #include "audio_stream_generator.h"
  
  void AudioStreamGenerator::set_mix_rate(float p_mix_rate) {
  	mix_rate = p_mix_rate;
  }
  
  float AudioStreamGenerator::get_mix_rate() const {
  
  	return mix_rate;
  }
  
  void AudioStreamGenerator::set_buffer_length(float p_seconds) {
  
  	buffer_len = p_seconds;
  }
  float AudioStreamGenerator::get_buffer_length() const {
  
  	return buffer_len;
  }
  
  Ref<AudioStreamPlayback> AudioStreamGenerator::instance_playback() {
  
  	Ref<AudioStreamGeneratorPlayback> playback;
  	playback.instance();
  	playback->generator = this;
  	int target_buffer_size = mix_rate * buffer_len;
  	playback->buffer.resize(nearest_shift(target_buffer_size));
  	playback->buffer.clear();
  	return playback;
  }
  String AudioStreamGenerator::get_stream_name() const {
  
  	return "UserFeed";
  }
  
  float AudioStreamGenerator::get_length() const {
  	return 0;
  }
  
  void AudioStreamGenerator::_bind_methods() {
  	ClassDB::bind_method(D_METHOD("set_mix_rate", "hz"), &AudioStreamGenerator::set_mix_rate);
  	ClassDB::bind_method(D_METHOD("get_mix_rate"), &AudioStreamGenerator::get_mix_rate);
  
  	ClassDB::bind_method(D_METHOD("set_buffer_length", "seconds"), &AudioStreamGenerator::set_buffer_length);
  	ClassDB::bind_method(D_METHOD("get_buffer_length"), &AudioStreamGenerator::get_buffer_length);
  
  	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "mix_rate", PROPERTY_HINT_RANGE, "20,192000,1"), "set_mix_rate", "get_mix_rate");
  	ADD_PROPERTY(PropertyInfo(Variant::FLOAT, "buffer_length", PROPERTY_HINT_RANGE, "0.01,10,0.01"), "set_buffer_length", "get_buffer_length");
  }
  
  AudioStreamGenerator::AudioStreamGenerator() {
  	mix_rate = 44100;
  	buffer_len = 0.5;
  }
  
  ////////////////
  
  bool AudioStreamGeneratorPlayback::push_frame(const Vector2 &p_frame) {
  	if (buffer.space_left() < 1) {
  		return false;
  	}
  
  	AudioFrame f = p_frame;
  
  	buffer.write(&f, 1);
  	return true;
  }
  
  bool AudioStreamGeneratorPlayback::can_push_buffer(int p_frames) const {
  	return buffer.space_left() >= p_frames;
  }
  bool AudioStreamGeneratorPlayback::push_buffer(const PackedVector2Array &p_frames) {
  
  	int to_write = p_frames.size();
  	if (buffer.space_left() < to_write) {
  		return false;
  	}
  
  	const Vector2 *r = p_frames.ptr();
  	if (sizeof(real_t) == 4) {
  		//write directly
  		buffer.write((const AudioFrame *)r, to_write);
  	} else {
  		//convert from double
  		AudioFrame buf[2048];
  		int ofs = 0;
  		while (to_write) {
  
  			int w = MIN(to_write, 2048);
  			for (int i = 0; i < w; i++) {
  				buf[i] = r[i + ofs];
  			}
  			buffer.write(buf, w);
  			ofs += w;
  			to_write -= w;
  		}
  	}
  	return true;
  }
  
  int AudioStreamGeneratorPlayback::get_frames_available() const {
  	return buffer.space_left();
  }
  
  int AudioStreamGeneratorPlayback::get_skips() const {
  	return skips;
  }
  
  void AudioStreamGeneratorPlayback::clear_buffer() {
  	ERR_FAIL_COND(active);
  	buffer.clear();
  	mixed = 0;
  }
  
  void AudioStreamGeneratorPlayback::_mix_internal(AudioFrame *p_buffer, int p_frames) {
  
  	int read_amount = buffer.data_left();
  	if (p_frames < read_amount) {
  		read_amount = p_frames;
  	}
  
  	buffer.read(p_buffer, read_amount);
  
  	if (read_amount < p_frames) {
  		//skipped, not ideal
  		for (int i = read_amount; i < p_frames; i++) {
  			p_buffer[i] = AudioFrame(0, 0);
  		}
  
  		skips++;
  	}
  
  	mixed += p_frames / generator->get_mix_rate();
  }
  float AudioStreamGeneratorPlayback::get_stream_sampling_rate() {
  	return generator->get_mix_rate();
  }
  
  void AudioStreamGeneratorPlayback::start(float p_from_pos) {
  
  	if (mixed == 0.0) {
  		_begin_resample();
  	}
  	skips = 0;
  	active = true;
  	mixed = 0.0;
  }
  
  void AudioStreamGeneratorPlayback::stop() {
  	active = false;
  }
  bool AudioStreamGeneratorPlayback::is_playing() const {
  
  	return active; //always playing, can't be stopped
  }
  
  int AudioStreamGeneratorPlayback::get_loop_count() const {
  	return 0;
  }
  
  float AudioStreamGeneratorPlayback::get_playback_position() const {
  	return mixed;
  }
  void AudioStreamGeneratorPlayback::seek(float p_time) {
  	//no seek possible
  }
  
  void AudioStreamGeneratorPlayback::_bind_methods() {
  	ClassDB::bind_method(D_METHOD("push_frame", "frame"), &AudioStreamGeneratorPlayback::push_frame);
  	ClassDB::bind_method(D_METHOD("can_push_buffer", "amount"), &AudioStreamGeneratorPlayback::can_push_buffer);
  	ClassDB::bind_method(D_METHOD("push_buffer", "frames"), &AudioStreamGeneratorPlayback::push_buffer);
  	ClassDB::bind_method(D_METHOD("get_frames_available"), &AudioStreamGeneratorPlayback::get_frames_available);
  	ClassDB::bind_method(D_METHOD("get_skips"), &AudioStreamGeneratorPlayback::get_skips);
  	ClassDB::bind_method(D_METHOD("clear_buffer"), &AudioStreamGeneratorPlayback::clear_buffer);
  }
  
  AudioStreamGeneratorPlayback::AudioStreamGeneratorPlayback() {
  	generator = nullptr;
  	skips = 0;
  	active = false;
  	mixed = 0;
  }
  