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/*
* Copyright (C) 2010, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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*/
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_AUDIO_RESAMPLER_KERNEL_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_AUDIO_RESAMPLER_KERNEL_H_
#include "third_party/blink/renderer/platform/audio/audio_array.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/wtf/allocator.h"
namespace blink {
class AudioResampler;
// AudioResamplerKernel does resampling on a single mono channel.
// It uses a simple linear interpolation for good performance.
class PLATFORM_EXPORT AudioResamplerKernel {
USING_FAST_MALLOC(AudioResamplerKernel);
public:
AudioResamplerKernel(AudioResampler*);
// getSourcePointer() should be called each time before process() is called.
// Given a number of frames to process (for subsequent call to process()), it
// returns a pointer and numberOfSourceFramesNeeded where sample data should
// be copied. This sample data provides the input to the resampler when
// process() is called. framesToProcess must be less than or equal to
// MaxFramesToProcess.
float* GetSourcePointer(uint32_t frames_to_process,
size_t* number_of_source_frames_needed);
// process() resamples framesToProcess frames from the source into
// destination. Each call to process() must be preceded by a call to
// getSourcePointer() so that source input may be supplied. framesToProcess
// must be less than or equal to MaxFramesToProcess.
void Process(float* destination, uint32_t frames_to_process);
// Resets the processing state.
void Reset();
static const size_t kMaxFramesToProcess;
private:
double Rate() const;
AudioResampler* resampler_;
AudioFloatArray source_buffer_;
// This is a (floating point) read index on the input stream.
double virtual_read_index_;
// We need to have continuity from one call of process() to the next.
// m_lastValues stores the last two sample values from the last call to
// process(). m_fillIndex represents how many buffered samples we have which
// can be as many as 2. For the first call to process() (or after reset())
// there will be no buffered samples.
float last_values_[2];
unsigned fill_index_;
DISALLOW_COPY_AND_ASSIGN(AudioResamplerKernel);
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_PLATFORM_AUDIO_AUDIO_RESAMPLER_KERNEL_H_