1/*
2 * Copyright (C) 2010 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1.  Redistributions of source code must retain the above copyright
9 *     notice, this list of conditions and the following disclaimer.
10 * 2.  Redistributions in binary form must reproduce the above copyright
11 *     notice, this list of conditions and the following disclaimer in the
12 *     documentation and/or other materials provided with the distribution.
13 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
14 *     its contributors may be used to endorse or promote products derived
15 *     from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef FFTConvolver_h
30#define FFTConvolver_h
31
32#include "platform/audio/AudioArray.h"
33#include "platform/audio/FFTFrame.h"
34
35namespace blink {
36
37class PLATFORM_EXPORT FFTConvolver {
38public:
39    // fftSize must be a power of two
40    FFTConvolver(size_t fftSize);
41
42    // For now, with multiple calls to Process(), framesToProcess MUST add up EXACTLY to fftSize / 2
43    //
44    // FIXME: Later, we can do more sophisticated buffering to relax this requirement...
45    //
46    // The input to output latency is equal to fftSize / 2
47    //
48    // Processing in-place is allowed...
49    void process(FFTFrame* fftKernel, const float* sourceP, float* destP, size_t framesToProcess);
50
51    void reset();
52
53    size_t fftSize() const { return m_frame.fftSize(); }
54
55private:
56    FFTFrame m_frame;
57
58    // Buffer input until we get fftSize / 2 samples then do an FFT
59    size_t m_readWriteIndex;
60    AudioFloatArray m_inputBuffer;
61
62    // Stores output which we read a little at a time
63    AudioFloatArray m_outputBuffer;
64
65    // Saves the 2nd half of the FFT buffer, so we can do an overlap-add with the 1st half of the next one
66    AudioFloatArray m_lastOverlapBuffer;
67};
68
69} // namespace blink
70
71#endif // FFTConvolver_h
72