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1 /* | 1 /* |
2 * Copyright (C) 2013 Google Inc. All rights reserved. | 2 * Copyright (C) 2013 Google Inc. All rights reserved. |
3 * | 3 * |
4 * Redistribution and use in source and binary forms, with or without | 4 * Redistribution and use in source and binary forms, with or without |
5 * modification, are permitted provided that the following conditions are | 5 * modification, are permitted provided that the following conditions are |
6 * met: | 6 * met: |
7 * | 7 * |
8 * * Redistributions of source code must retain the above copyright | 8 * * Redistributions of source code must retain the above copyright |
9 * notice, this list of conditions and the following disclaimer. | 9 * notice, this list of conditions and the following disclaimer. |
10 * * Redistributions in binary form must reproduce the above | 10 * * Redistributions in binary form must reproduce the above |
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60 int halfSize = n / 2; | 60 int halfSize = n / 2; |
61 double subsampleOffset = -0.5; | 61 double subsampleOffset = -0.5; |
62 | 62 |
63 for (int i = 0; i < n; ++i) { | 63 for (int i = 0; i < n; ++i) { |
64 // Compute the sinc() with offset. | 64 // Compute the sinc() with offset. |
65 double s = piDouble * (i - halfSize - subsampleOffset); | 65 double s = piDouble * (i - halfSize - subsampleOffset); |
66 double sinc = !s ? 1.0 : sin(s) / s; | 66 double sinc = !s ? 1.0 : sin(s) / s; |
67 | 67 |
68 // Compute Blackman window, matching the offset of the sinc(). | 68 // Compute Blackman window, matching the offset of the sinc(). |
69 double x = (i - subsampleOffset) / n; | 69 double x = (i - subsampleOffset) / n; |
70 double window = a0 - a1 * cos(2.0 * piDouble * x) + a2 * cos(4.0 * piDou
ble * x); | 70 double window = a0 - a1 * cos(twoPiDouble * x) + a2 * cos(twoPiDouble *
2.0 * x); |
71 | 71 |
72 // Window the sinc() function. | 72 // Window the sinc() function. |
73 m_kernel[i] = sinc * window; | 73 m_kernel[i] = sinc * window; |
74 } | 74 } |
75 } | 75 } |
76 | 76 |
77 void UpSampler::process(const float* sourceP, float* destP, size_t sourceFramesT
oProcess) | 77 void UpSampler::process(const float* sourceP, float* destP, size_t sourceFramesT
oProcess) |
78 { | 78 { |
79 bool isInputBlockSizeGood = sourceFramesToProcess == m_inputBlockSize; | 79 bool isInputBlockSizeGood = sourceFramesToProcess == m_inputBlockSize; |
80 ASSERT(isInputBlockSizeGood); | 80 ASSERT(isInputBlockSizeGood); |
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125 | 125 |
126 size_t UpSampler::latencyFrames() const | 126 size_t UpSampler::latencyFrames() const |
127 { | 127 { |
128 // Divide by two since this is a linear phase kernel and the delay is at the
center of the kernel. | 128 // Divide by two since this is a linear phase kernel and the delay is at the
center of the kernel. |
129 return m_kernel.size() / 2; | 129 return m_kernel.size() / 2; |
130 } | 130 } |
131 | 131 |
132 } // namespace WebCore | 132 } // namespace WebCore |
133 | 133 |
134 #endif // ENABLE(WEB_AUDIO) | 134 #endif // ENABLE(WEB_AUDIO) |
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