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1 /* | 1 /* |
2 * Copyright (C) 2010, Google Inc. All rights reserved. | 2 * Copyright (C) 2010, 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 | 5 * modification, are permitted provided that the following conditions |
6 * are met: | 6 * are met: |
7 * 1. Redistributions of source code must retain the above copyright | 7 * 1. Redistributions of source code must retain the above copyright |
8 * notice, this list of conditions and the following disclaimer. | 8 * notice, this list of conditions and the following disclaimer. |
9 * 2. Redistributions in binary form must reproduce the above copyright | 9 * 2. Redistributions in binary form must reproduce the above copyright |
10 * notice, this list of conditions and the following disclaimer in the | 10 * notice, this list of conditions and the following disclaimer in the |
11 * documentation and/or other materials provided with the distribution. | 11 * documentation and/or other materials provided with the distribution. |
12 * | 12 * |
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND AN Y | 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND AN Y |
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED | 14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE | 15 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR AN Y | 16 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR AN Y |
17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES | 17 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES |
18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | 18 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND O N | 19 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND O N |
20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | 20 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | 22 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
23 */ | 23 */ |
24 | 24 |
25 #include "config.h" | 25 #include "config.h" |
26 | 26 |
27 #if ENABLE(WEB_AUDIO) | 27 #if ENABLE(WEB_AUDIO) |
28 | 28 |
29 #include "platform/audio/AudioUtilities.h" | 29 #include "platform/audio/AudioUtilities.h" |
30 | |
30 #include "wtf/Assertions.h" | 31 #include "wtf/Assertions.h" |
31 #include "wtf/MathExtras.h" | 32 #include "wtf/MathExtras.h" |
32 | 33 |
33 namespace blink { | 34 namespace blink { |
34 | 35 |
35 namespace AudioUtilities { | 36 namespace AudioUtilities { |
36 | 37 |
37 float decibelsToLinear(float decibels) | 38 float decibelsToLinear(float decibels) |
38 { | 39 { |
39 return powf(10, 0.05f * decibels); | 40 return powf(10, 0.05f * decibels); |
(...skipping 12 matching lines...) Expand all Loading... | |
52 | 53 |
53 double discreteTimeConstantForSampleRate(double timeConstant, double sampleRate) | 54 double discreteTimeConstantForSampleRate(double timeConstant, double sampleRate) |
54 { | 55 { |
55 return 1 - exp(-1 / (sampleRate * timeConstant)); | 56 return 1 - exp(-1 / (sampleRate * timeConstant)); |
56 } | 57 } |
57 | 58 |
58 size_t timeToSampleFrame(double time, double sampleRate) | 59 size_t timeToSampleFrame(double time, double sampleRate) |
59 { | 60 { |
60 return static_cast<size_t>(round(time * sampleRate)); | 61 return static_cast<size_t>(round(time * sampleRate)); |
61 } | 62 } |
63 | |
64 bool isSampleRateRangeGood(float sampleRate) | |
65 { | |
66 return sampleRate >= minAllowedSampleRate() && sampleRate <= maxAllowedSampl eRate(); | |
67 } | |
68 | |
69 size_t fftSizeForSampleRate(float sampleRate) | |
70 { | |
71 // Currently, we truncate the impulse responses to half this size, | |
Raymond Toy
2014/09/11 16:38:45
Need more context here because "this size" has no
KhNo
2014/09/12 15:01:05
Done.
| |
72 // but an FFT-size of twice impulse response size is needed (for convolution ). | |
73 // So for sample rates around 44.1KHz an FFT size of 512 is good. | |
74 // For different sample rates, the truncated response is resampled. | |
75 // The resampled length is used to compute the FFT size by choosing a power of two that is | |
76 // greater than or equal the resampled length. This power of two is doubled to get the actual FFT size. | |
77 | |
78 ASSERT(isSampleRateRangeGood(sampleRate)); | |
79 | |
80 int truncatedImpulseLength = 256; | |
81 double sampleRateRatio = sampleRate / 44100; | |
82 double resampledLength = truncatedImpulseLength * sampleRateRatio; | |
83 | |
84 return 2 * (1 << static_cast<unsigned>(log2(resampledLength))); | |
85 } | |
86 | |
87 float minAllowedSampleRate() | |
88 { | |
89 // crbug.com/344375 | |
90 return 3000; | |
91 } | |
92 | |
93 float maxAllowedSampleRate() | |
94 { | |
95 // Windows can support up to this rate. | |
96 return 192000; | |
97 } | |
62 } // AudioUtilites | 98 } // AudioUtilites |
63 | 99 |
64 } // namespace blink | 100 } // namespace blink |
65 | 101 |
66 #endif // ENABLE(WEB_AUDIO) | 102 #endif // ENABLE(WEB_AUDIO) |
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