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/*************************************************************************/
/* audio_stream.cpp */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* http://www.godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2017 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.h"
//////////////////////////////
void AudioStreamPlaybackResampled::_begin_resample() {
//clear cubic interpolation history
internal_buffer[0] = AudioFrame(0.0, 0.0);
internal_buffer[1] = AudioFrame(0.0, 0.0);
internal_buffer[2] = AudioFrame(0.0, 0.0);
internal_buffer[3] = AudioFrame(0.0, 0.0);
//mix buffer
_mix_internal(internal_buffer + 4, INTERNAL_BUFFER_LEN);
mix_offset = 0;
}
void AudioStreamPlaybackResampled::mix(AudioFrame *p_buffer, float p_rate_scale, int p_frames) {
float target_rate = AudioServer::get_singleton()->get_mix_rate() * p_rate_scale;
uint64_t mix_increment = uint64_t((get_stream_sampling_rate() / double(target_rate)) * double(FP_LEN));
for (int i = 0; i < p_frames; i++) {
uint32_t idx = CUBIC_INTERP_HISTORY + uint32_t(mix_offset >> FP_BITS);
//standard cubic interpolation (great quality/performance ratio)
//this used to be moved to a LUT for greater performance, but nowadays CPU speed is generally faster than memory.
float mu = (mix_offset & FP_MASK) / float(FP_LEN);
AudioFrame y0 = internal_buffer[idx - 3];
AudioFrame y1 = internal_buffer[idx - 2];
AudioFrame y2 = internal_buffer[idx - 1];
AudioFrame y3 = internal_buffer[idx - 0];
float mu2 = mu * mu;
AudioFrame a0 = y3 - y2 - y0 + y1;
AudioFrame a1 = y0 - y1 - a0;
AudioFrame a2 = y2 - y0;
AudioFrame a3 = y1;
p_buffer[i] = (a0 * mu * mu2 + a1 * mu2 + a2 * mu + a3);
mix_offset += mix_increment;
while ((mix_offset >> FP_BITS) >= INTERNAL_BUFFER_LEN) {
internal_buffer[0] = internal_buffer[INTERNAL_BUFFER_LEN + 0];
internal_buffer[1] = internal_buffer[INTERNAL_BUFFER_LEN + 1];
internal_buffer[2] = internal_buffer[INTERNAL_BUFFER_LEN + 2];
internal_buffer[3] = internal_buffer[INTERNAL_BUFFER_LEN + 3];
_mix_internal(internal_buffer + 4, INTERNAL_BUFFER_LEN);
mix_offset -= (INTERNAL_BUFFER_LEN << FP_BITS);
}
}
}
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