Alejandro Luebs | a9c0ae2 | 2015-04-14 15:51:28 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2015 The WebRTC project authors. All Rights Reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
Mirko Bonadei | 92ea95e | 2017-09-15 06:47:31 +0200 | [diff] [blame] | 11 | #ifndef COMMON_AUDIO_SPARSE_FIR_FILTER_H_ |
| 12 | #define COMMON_AUDIO_SPARSE_FIR_FILTER_H_ |
Alejandro Luebs | a9c0ae2 | 2015-04-14 15:51:28 -0700 | [diff] [blame] | 13 | |
| 14 | #include <cstring> |
| 15 | #include <vector> |
| 16 | |
Steve Anton | 10542f2 | 2019-01-11 09:11:00 -0800 | [diff] [blame] | 17 | #include "rtc_base/constructor_magic.h" |
Alejandro Luebs | 5a92aa8 | 2015-04-27 11:34:45 -0700 | [diff] [blame] | 18 | |
Alejandro Luebs | a9c0ae2 | 2015-04-14 15:51:28 -0700 | [diff] [blame] | 19 | namespace webrtc { |
| 20 | |
| 21 | // A Finite Impulse Response filter implementation which takes advantage of a |
| 22 | // sparse structure with uniformly distributed non-zero coefficients. |
Alejandro Luebs | 5a92aa8 | 2015-04-27 11:34:45 -0700 | [diff] [blame] | 23 | class SparseFIRFilter final { |
Alejandro Luebs | a9c0ae2 | 2015-04-14 15:51:28 -0700 | [diff] [blame] | 24 | public: |
| 25 | // |num_nonzero_coeffs| is the number of non-zero coefficients, |
| 26 | // |nonzero_coeffs|. They are assumed to be uniformly distributed every |
| 27 | // |sparsity| samples and with an initial |offset|. The rest of the filter |
| 28 | // coefficients will be assumed zeros. For example, with sparsity = 3, and |
| 29 | // offset = 1 the filter coefficients will be: |
| 30 | // B = [0 coeffs[0] 0 0 coeffs[1] 0 0 coeffs[2] ... ] |
| 31 | // All initial state values will be zeros. |
| 32 | SparseFIRFilter(const float* nonzero_coeffs, |
Peter Kasting | dce40cf | 2015-08-24 14:52:23 -0700 | [diff] [blame] | 33 | size_t num_nonzero_coeffs, |
| 34 | size_t sparsity, |
| 35 | size_t offset); |
kwiberg | 9e10211 | 2016-08-29 13:43:01 -0700 | [diff] [blame] | 36 | ~SparseFIRFilter(); |
Alejandro Luebs | a9c0ae2 | 2015-04-14 15:51:28 -0700 | [diff] [blame] | 37 | |
| 38 | // Filters the |in| data supplied. |
| 39 | // |out| must be previously allocated and it must be at least of |length|. |
Peter Kasting | dce40cf | 2015-08-24 14:52:23 -0700 | [diff] [blame] | 40 | void Filter(const float* in, size_t length, float* out); |
Alejandro Luebs | a9c0ae2 | 2015-04-14 15:51:28 -0700 | [diff] [blame] | 41 | |
| 42 | private: |
Peter Kasting | dce40cf | 2015-08-24 14:52:23 -0700 | [diff] [blame] | 43 | const size_t sparsity_; |
| 44 | const size_t offset_; |
Alejandro Luebs | a9c0ae2 | 2015-04-14 15:51:28 -0700 | [diff] [blame] | 45 | const std::vector<float> nonzero_coeffs_; |
| 46 | std::vector<float> state_; |
Alejandro Luebs | 5a92aa8 | 2015-04-27 11:34:45 -0700 | [diff] [blame] | 47 | |
henrikg | 3c089d7 | 2015-09-16 05:37:44 -0700 | [diff] [blame] | 48 | RTC_DISALLOW_COPY_AND_ASSIGN(SparseFIRFilter); |
Alejandro Luebs | a9c0ae2 | 2015-04-14 15:51:28 -0700 | [diff] [blame] | 49 | }; |
| 50 | |
| 51 | } // namespace webrtc |
| 52 | |
Mirko Bonadei | 92ea95e | 2017-09-15 06:47:31 +0200 | [diff] [blame] | 53 | #endif // COMMON_AUDIO_SPARSE_FIR_FILTER_H_ |