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 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, 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 WebCore
119
120#endif // ENABLE(WEB_AUDIO)
121