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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 |
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29 | 29 |
30 namespace blink { | 30 namespace blink { |
31 | 31 |
32 namespace AudioUtilities { | 32 namespace AudioUtilities { |
33 | 33 |
34 float decibelsToLinear(float decibels) { | 34 float decibelsToLinear(float decibels) { |
35 return powf(10, 0.05f * decibels); | 35 return powf(10, 0.05f * decibels); |
36 } | 36 } |
37 | 37 |
38 float linearToDecibels(float linear) { | 38 float linearToDecibels(float linear) { |
39 DCHECK_GE(linear, 0); | 39 ASSERT(linear >= 0); |
40 | 40 |
41 return 20 * log10f(linear); | 41 return 20 * log10f(linear); |
42 } | 42 } |
43 | 43 |
44 double discreteTimeConstantForSampleRate(double timeConstant, | 44 double discreteTimeConstantForSampleRate(double timeConstant, |
45 double sampleRate) { | 45 double sampleRate) { |
46 return 1 - exp(-1 / (sampleRate * timeConstant)); | 46 return 1 - exp(-1 / (sampleRate * timeConstant)); |
47 } | 47 } |
48 | 48 |
49 size_t timeToSampleFrame(double time, double sampleRate) { | 49 size_t timeToSampleFrame(double time, double sampleRate) { |
50 DCHECK_GE(time, 0); | 50 ASSERT(time >= 0); |
51 double frame = round(time * sampleRate); | 51 double frame = round(time * sampleRate); |
52 | 52 |
53 // Just return the largest possible size_t value if necessary. | 53 // Just return the largest possible size_t value if necessary. |
54 if (frame >= std::numeric_limits<size_t>::max()) { | 54 if (frame >= std::numeric_limits<size_t>::max()) { |
55 return std::numeric_limits<size_t>::max(); | 55 return std::numeric_limits<size_t>::max(); |
56 } | 56 } |
57 | 57 |
58 return static_cast<size_t>(frame); | 58 return static_cast<size_t>(frame); |
59 } | 59 } |
60 | 60 |
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77 bool isPowerOfTwo(size_t x) { | 77 bool isPowerOfTwo(size_t x) { |
78 // From Hacker's Delight. x & (x - 1) turns off (zeroes) the | 78 // From Hacker's Delight. x & (x - 1) turns off (zeroes) the |
79 // rightmost 1-bit in the word x. If x is a power of two, then the | 79 // rightmost 1-bit in the word x. If x is a power of two, then the |
80 // result is, of course, 0. | 80 // result is, of course, 0. |
81 return x > 0 && ((x & (x - 1)) == 0); | 81 return x > 0 && ((x & (x - 1)) == 0); |
82 } | 82 } |
83 | 83 |
84 } // namespace AudioUtilities | 84 } // namespace AudioUtilities |
85 | 85 |
86 } // namespace blink | 86 } // namespace blink |
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