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84 lines
4.0 KiB
C++
84 lines
4.0 KiB
C++
/*************************************************************************/
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/* audio_stream.cpp */
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/*************************************************************************/
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/* This file is part of: */
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/* GODOT ENGINE */
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/* http://www.godotengine.org */
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/*************************************************************************/
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/* Copyright (c) 2007-2017 Juan Linietsky, Ariel Manzur. */
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/* Copyright (c) 2014-2017 Godot Engine contributors (cf. AUTHORS.md) */
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/* */
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/* Permission is hereby granted, free of charge, to any person obtaining */
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/* a copy of this software and associated documentation files (the */
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/* "Software"), to deal in the Software without restriction, including */
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/* without limitation the rights to use, copy, modify, merge, publish, */
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/* distribute, sublicense, and/or sell copies of the Software, and to */
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/* permit persons to whom the Software is furnished to do so, subject to */
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/* the following conditions: */
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/* */
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/* The above copyright notice and this permission notice shall be */
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/* included in all copies or substantial portions of the Software. */
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/* */
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/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
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/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
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/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
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/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
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/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
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/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
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/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
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/*************************************************************************/
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#include "audio_stream.h"
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//////////////////////////////
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void AudioStreamPlaybackResampled::_begin_resample() {
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//clear cubic interpolation history
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internal_buffer[0] = AudioFrame(0.0, 0.0);
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internal_buffer[1] = AudioFrame(0.0, 0.0);
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internal_buffer[2] = AudioFrame(0.0, 0.0);
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internal_buffer[3] = AudioFrame(0.0, 0.0);
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//mix buffer
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_mix_internal(internal_buffer + 4, INTERNAL_BUFFER_LEN);
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mix_offset = 0;
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}
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void AudioStreamPlaybackResampled::mix(AudioFrame *p_buffer, float p_rate_scale, int p_frames) {
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float target_rate = AudioServer::get_singleton()->get_mix_rate() * p_rate_scale;
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uint64_t mix_increment = uint64_t((get_stream_sampling_rate() / double(target_rate)) * double(FP_LEN));
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for (int i = 0; i < p_frames; i++) {
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uint32_t idx = CUBIC_INTERP_HISTORY + uint32_t(mix_offset >> FP_BITS);
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//standard cubic interpolation (great quality/performance ratio)
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//this used to be moved to a LUT for greater performance, but nowadays CPU speed is generally faster than memory.
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float mu = (mix_offset & FP_MASK) / float(FP_LEN);
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AudioFrame y0 = internal_buffer[idx - 3];
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AudioFrame y1 = internal_buffer[idx - 2];
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AudioFrame y2 = internal_buffer[idx - 1];
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AudioFrame y3 = internal_buffer[idx - 0];
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float mu2 = mu * mu;
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AudioFrame a0 = y3 - y2 - y0 + y1;
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AudioFrame a1 = y0 - y1 - a0;
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AudioFrame a2 = y2 - y0;
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AudioFrame a3 = y1;
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p_buffer[i] = (a0 * mu * mu2 + a1 * mu2 + a2 * mu + a3);
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mix_offset += mix_increment;
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while ((mix_offset >> FP_BITS) >= INTERNAL_BUFFER_LEN) {
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internal_buffer[0] = internal_buffer[INTERNAL_BUFFER_LEN + 0];
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internal_buffer[1] = internal_buffer[INTERNAL_BUFFER_LEN + 1];
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internal_buffer[2] = internal_buffer[INTERNAL_BUFFER_LEN + 2];
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internal_buffer[3] = internal_buffer[INTERNAL_BUFFER_LEN + 3];
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_mix_internal(internal_buffer + 4, INTERNAL_BUFFER_LEN);
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mix_offset -= (INTERNAL_BUFFER_LEN << FP_BITS);
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}
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}
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}
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