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#include "config.h"
30
31#if ENABLE(WEB_AUDIO)
32
33#include "FFTConvolver.h"
34
35#include "VectorMath.h"
36
37namespace WebCore {
38
39using namespace VectorMath;
40
41FFTConvolver::FFTConvolver(size_t fftSize)
42    : m_frame(fftSize)
43    , m_readWriteIndex(0)
44    , m_inputBuffer(fftSize) // 2nd half of buffer is always zeroed
45    , m_outputBuffer(fftSize)
46    , m_lastOverlapBuffer(fftSize / 2)
47{
48}
49
50void FFTConvolver::process(FFTFrame* fftKernel, float* sourceP, float* destP, size_t framesToProcess)
51{
52    // FIXME: make so framesToProcess is not required to fit evenly into fftSize/2
53
54    // Copy samples to input buffer (note contraint above!)
55    float* inputP = m_inputBuffer.data();
56
57    // Sanity check
58    bool isCopyGood1 = sourceP && inputP && m_readWriteIndex + framesToProcess <= m_inputBuffer.size();
59    ASSERT(isCopyGood1);
60    if (!isCopyGood1)
61        return;
62
63    memcpy(inputP + m_readWriteIndex, sourceP, sizeof(float) * framesToProcess);
64
65    // Copy samples from output buffer
66    float* outputP = m_outputBuffer.data();
67
68    // Sanity check
69    bool isCopyGood2 = destP && outputP && m_readWriteIndex + framesToProcess <= m_outputBuffer.size();
70    ASSERT(isCopyGood2);
71    if (!isCopyGood2)
72        return;
73
74    memcpy(destP, outputP + m_readWriteIndex, sizeof(float) * framesToProcess);
75    m_readWriteIndex += framesToProcess;
76
77
78    // Check if it's time to perform the next FFT
79    size_t halfSize = fftSize() / 2;
80    if (m_readWriteIndex == halfSize) {
81        // The input buffer is now filled (get frequency-domain version)
82        m_frame.doFFT(m_inputBuffer.data());
83        m_frame.multiply(*fftKernel);
84        m_frame.doInverseFFT(m_outputBuffer.data());
85
86        // Overlap-add 1st half from previous time
87        vadd(m_outputBuffer.data(), 1, m_lastOverlapBuffer.data(), 1, m_outputBuffer.data(), 1, halfSize);
88
89        // Finally, save 2nd half of result
90        bool isCopyGood3 = m_outputBuffer.size() == 2 * halfSize && m_lastOverlapBuffer.size() == halfSize;
91        ASSERT(isCopyGood3);
92        if (!isCopyGood3)
93            return;
94
95        memcpy(m_lastOverlapBuffer.data(), m_outputBuffer.data() + halfSize, sizeof(float) * halfSize);
96
97        // Reset index back to start for next time
98        m_readWriteIndex = 0;
99    }
100}
101
102void FFTConvolver::reset()
103{
104    m_lastOverlapBuffer.zero();
105    m_readWriteIndex = 0;
106}
107
108} // namespace WebCore
109
110#endif // ENABLE(WEB_AUDIO)
111