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 "platform/audio/FFTConvolver.h"
34
35#include "platform/audio/VectorMath.h"
36
37namespace blink {
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, const float* sourceP, float* destP, size_t framesToProcess)
51{
52    size_t halfSize = fftSize() / 2;
53
54    // framesToProcess must be an exact multiple of halfSize,
55    // or halfSize is a multiple of framesToProcess when halfSize > framesToProcess.
56    bool isGood = !(halfSize % framesToProcess && framesToProcess % halfSize);
57    ASSERT(isGood);
58    if (!isGood)
59        return;
60
61    size_t numberOfDivisions = halfSize <= framesToProcess ? (framesToProcess / halfSize) : 1;
62    size_t divisionSize = numberOfDivisions == 1 ? framesToProcess : halfSize;
63
64    for (size_t i = 0; i < numberOfDivisions; ++i, sourceP += divisionSize, destP += divisionSize) {
65        // Copy samples to input buffer (note contraint above!)
66        float* inputP = m_inputBuffer.data();
67
68        // Sanity check
69        bool isCopyGood1 = sourceP && inputP && m_readWriteIndex + divisionSize <= m_inputBuffer.size();
70        ASSERT(isCopyGood1);
71        if (!isCopyGood1)
72            return;
73
74        memcpy(inputP + m_readWriteIndex, sourceP, sizeof(float) * divisionSize);
75
76        // Copy samples from output buffer
77        float* outputP = m_outputBuffer.data();
78
79        // Sanity check
80        bool isCopyGood2 = destP && outputP && m_readWriteIndex + divisionSize <= m_outputBuffer.size();
81        ASSERT(isCopyGood2);
82        if (!isCopyGood2)
83            return;
84
85        memcpy(destP, outputP + m_readWriteIndex, sizeof(float) * divisionSize);
86        m_readWriteIndex += divisionSize;
87
88        // Check if it's time to perform the next FFT
89        if (m_readWriteIndex == halfSize) {
90            // The input buffer is now filled (get frequency-domain version)
91            m_frame.doFFT(m_inputBuffer.data());
92            m_frame.multiply(*fftKernel);
93            m_frame.doInverseFFT(m_outputBuffer.data());
94
95            // Overlap-add 1st half from previous time
96            vadd(m_outputBuffer.data(), 1, m_lastOverlapBuffer.data(), 1, m_outputBuffer.data(), 1, halfSize);
97
98            // Finally, save 2nd half of result
99            bool isCopyGood3 = m_outputBuffer.size() == 2 * halfSize && m_lastOverlapBuffer.size() == halfSize;
100            ASSERT(isCopyGood3);
101            if (!isCopyGood3)
102                return;
103
104            memcpy(m_lastOverlapBuffer.data(), m_outputBuffer.data() + halfSize, sizeof(float) * halfSize);
105
106            // Reset index back to start for next time
107            m_readWriteIndex = 0;
108        }
109    }
110}
111
112void FFTConvolver::reset()
113{
114    m_lastOverlapBuffer.zero();
115    m_readWriteIndex = 0;
116}
117
118} // namespace blink
119
120#endif // ENABLE(WEB_AUDIO)
121