86 lines
3.9 KiB
C++
86 lines
3.9 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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/* */
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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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