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
37 namespace WebCore {
38
39 using namespace VectorMath;
40
FFTConvolver(size_t fftSize)41 FFTConvolver::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
process(FFTFrame * fftKernel,float * sourceP,float * destP,size_t framesToProcess)50 void 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
reset()102 void FFTConvolver::reset()
103 {
104 m_lastOverlapBuffer.zero();
105 m_readWriteIndex = 0;
106 }
107
108 } // namespace WebCore
109
110 #endif // ENABLE(WEB_AUDIO)
111