| 1 | /* |
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| 2 | Copyright 2018 Google Inc. All Rights Reserved. |
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| 3 | |
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| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
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| 5 | you may not use this file except in compliance with the License. |
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| 6 | You may obtain a copy of the License at |
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| 7 | |
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| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
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| 9 | |
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| 10 | Unless required by applicable law or agreed to in writing, software |
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| 11 | distributed under the License is distributed on an "AS-IS" BASIS, |
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| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 13 | See the License for the specific language governing permissions and |
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| 14 | limitations under the License. |
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| 15 | */ |
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| 16 | |
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| 17 | #ifndef RESONANCE_AUDIO_DSP_GAIN_H_ |
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| 18 | #define RESONANCE_AUDIO_DSP_GAIN_H_ |
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| 19 | |
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| 20 | #include <cstddef> |
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| 21 | #include "base/audio_buffer.h" |
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| 22 | |
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| 23 | namespace vraudio { |
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| 24 | |
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| 25 | // Implements a linearly-interpolated application of gain to a buffer channel. |
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| 26 | // |
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| 27 | // @param ramp_length Length of interpolation ramp in samples. Must be > 0. |
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| 28 | // @param start_gain Starting gain value for ramp. |
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| 29 | // @param end_gain Finishing gain value for ramp. |
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| 30 | // @param input_samples Channel buffer to which interpolated gain is applied. |
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| 31 | // @param output_samples Channel buffer to contain scaled output. |
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| 32 | // @param accumulate_output True if the processed input should be mixed into the |
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| 33 | // output. Otherwise, the output will be replaced by the processed input. |
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| 34 | // @return Next gain value to be applied to the buffer channel. |
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| 35 | float LinearGainRamp(size_t ramp_length, float start_gain, float end_gain, |
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| 36 | const AudioBuffer::Channel& input_samples, |
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| 37 | AudioBuffer::Channel* output_samples, |
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| 38 | bool accumulate_output); |
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| 39 | |
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| 40 | // Applies a gain value to a vector of buffer samples starting at some offset. |
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| 41 | // |
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| 42 | // @param offset_index Starting index for gain application in buffer. |
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| 43 | // @param gain Gain value applied to samples. |
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| 44 | // @param input_samples Channel buffer to which gain is applied. |
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| 45 | // @param output_samples Channel buffer to contain scaled output. |
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| 46 | // @param accumulate_output True if the processed input should be mixed into the |
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| 47 | // output. Otherwise, the output will be replaced by the processed input. |
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| 48 | void ConstantGain(size_t offset_index, float gain, |
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| 49 | const AudioBuffer::Channel& input_samples, |
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| 50 | AudioBuffer::Channel* output_samples, bool accumulate_output); |
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| 51 | |
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| 52 | // Checks if the gain factor is close enough to zero (less than -60 decibels). |
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| 53 | // |
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| 54 | // @param gain Gain value to be tested. |
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| 55 | // @return true if the current gain factors are near zero, false otherwise. |
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| 56 | bool IsGainNearZero(float gain); |
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| 57 | |
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| 58 | // Checks if the gain state is close enough to Unity (less than -60 decibels |
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| 59 | // below or above). |
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| 60 | // |
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| 61 | // @param gain Gain value to be tested. |
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| 62 | // @return true if the current gain factors are near unity, false otherwise. |
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| 63 | bool IsGainNearUnity(float gain); |
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| 64 | |
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| 65 | } // namespace vraudio |
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| 66 | |
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| 67 | #endif // RESONANCE_AUDIO_DSP_GAIN_H_ |
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| 68 | |
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