| 1 | /* |
|---|
| 2 | Copyright 2018 Google Inc. All Rights Reserved. |
|---|
| 3 | |
|---|
| 4 | Licensed under the Apache License, Version 2.0 (the "License"); |
|---|
| 5 | you may not use this file except in compliance with the License. |
|---|
| 6 | You may obtain a copy of the License at |
|---|
| 7 | |
|---|
| 8 | http://www.apache.org/licenses/LICENSE-2.0 |
|---|
| 9 | |
|---|
| 10 | Unless required by applicable law or agreed to in writing, software |
|---|
| 11 | distributed under the License is distributed on an "AS-IS" BASIS, |
|---|
| 12 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
|---|
| 13 | See the License for the specific language governing permissions and |
|---|
| 14 | limitations under the License. |
|---|
| 15 | */ |
|---|
| 16 | |
|---|
| 17 | #ifndef RESONANCE_AUDIO_DSP_UTILS_H_ |
|---|
| 18 | #define RESONANCE_AUDIO_DSP_UTILS_H_ |
|---|
| 19 | |
|---|
| 20 | #include "base/audio_buffer.h" |
|---|
| 21 | |
|---|
| 22 | namespace vraudio { |
|---|
| 23 | |
|---|
| 24 | // Generates a gaussian white noise signal. |
|---|
| 25 | // |
|---|
| 26 | // @param mean The mean distribution parameter. |
|---|
| 27 | // @param std_deviation The standard deviation distribution parameter. |
|---|
| 28 | // @param seed A seed for the random generator. |
|---|
| 29 | // @param noise_channel Buffer channel in which to store the noise. |
|---|
| 30 | void GenerateGaussianNoise(float mean, float std_deviation, unsigned seed, |
|---|
| 31 | AudioBuffer::Channel* noise_channel); |
|---|
| 32 | |
|---|
| 33 | // Generates a gaussian white noise signal. |
|---|
| 34 | // |
|---|
| 35 | // @param min The lowest value in the distribution. |
|---|
| 36 | // @param max The highest value in te distribution, must be > min. |
|---|
| 37 | // @param seed A seed for the random generator. |
|---|
| 38 | // @param noise_channel Buffer channel in which to store the noise. |
|---|
| 39 | void GenerateUniformNoise(float min, float max, unsigned seed, |
|---|
| 40 | AudioBuffer::Channel* noise_channel); |
|---|
| 41 | |
|---|
| 42 | // Generates a band limited gaussian white noise signal, one octave band wide. |
|---|
| 43 | // |
|---|
| 44 | // @param center_frequency Center frequency of the given octave band in Hz. |
|---|
| 45 | // @param sampling_rate System sampling rate in Hz. |
|---|
| 46 | // @param seed A seed for the random generator. |
|---|
| 47 | // @param noise_buffer Buffer in which to store the band limited noise. |
|---|
| 48 | void GenerateBandLimitedGaussianNoise(float center_frequency, int sampling_rate, |
|---|
| 49 | unsigned seed, AudioBuffer* noise_buffer); |
|---|
| 50 | |
|---|
| 51 | // Genarates a pair of decorrelation filters (for use in low quality/high |
|---|
| 52 | // effiency mode reverb). |
|---|
| 53 | // |
|---|
| 54 | // @param sampling_rate System sampling rate in Hz. |
|---|
| 55 | // @return Buffer containing the stereo filters. |
|---|
| 56 | std::unique_ptr<AudioBuffer> GenerateDecorrelationFilters(int sampling_rate); |
|---|
| 57 | |
|---|
| 58 | // Returns the number of octave bands necessary for the given |sampling_rate|. |
|---|
| 59 | // |
|---|
| 60 | // @param sampling_rate Sampling rate in Hertz. |
|---|
| 61 | // @return Number of reverb octave bands. |
|---|
| 62 | size_t GetNumReverbOctaveBands(int sampling_rate); |
|---|
| 63 | |
|---|
| 64 | // Converts the given |milliseconds| to number of samples with the given |
|---|
| 65 | // |sampling_rate|. This method should *not* be used when more precise |
|---|
| 66 | // (double-precission) value is desired. |
|---|
| 67 | // |
|---|
| 68 | // @param milliseconds Milliseconds in single-precission floating point. |
|---|
| 69 | // @param sampling_rate Sampling rate in Hertz. |
|---|
| 70 | // @return Number of samples. |
|---|
| 71 | size_t GetNumSamplesFromMilliseconds(float milliseconds, int sampling_rate); |
|---|
| 72 | |
|---|
| 73 | // Ceils the given |size| to the next multiple of given |frames_per_buffer|. |
|---|
| 74 | // |
|---|
| 75 | // @param size Input size in frames. |
|---|
| 76 | // @param frames_per_buffer Frames per buffer. |
|---|
| 77 | // @return Ceiled size in frames. |
|---|
| 78 | size_t CeilToMultipleOfFramesPerBuffer(size_t size, size_t frames_per_buffer); |
|---|
| 79 | |
|---|
| 80 | // Generates a Hann window (used for smooth onset and tapering of the generated |
|---|
| 81 | // reverb response tails). |
|---|
| 82 | // |
|---|
| 83 | // @param full_window True to generate a full window, false to generate a half. |
|---|
| 84 | // @param window_length Length of the window to be generated. Must be less than |
|---|
| 85 | // or equal to the number of frames in the |buffer|. |
|---|
| 86 | // @param buffer AudioBuffer::Channel to which the window is written, the number |
|---|
| 87 | // of frames will be the length in samples of the generated Hann window. |
|---|
| 88 | void GenerateHannWindow(bool full_window, size_t window_length, |
|---|
| 89 | AudioBuffer::Channel* buffer); |
|---|
| 90 | |
|---|
| 91 | } // namespace vraudio |
|---|
| 92 | |
|---|
| 93 | #endif // RESONANCE_AUDIO_DSP_UTILS_H_ |
|---|
| 94 | |
|---|
