54 lines
1.8 KiB
C++
54 lines
1.8 KiB
C++
/*
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* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef COMMON_AUDIO_SPARSE_FIR_FILTER_H_
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#define COMMON_AUDIO_SPARSE_FIR_FILTER_H_
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#include <cstring>
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#include <vector>
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#include "rtc_base/constructormagic.h"
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namespace webrtc {
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// A Finite Impulse Response filter implementation which takes advantage of a
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// sparse structure with uniformly distributed non-zero coefficients.
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class SparseFIRFilter final {
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public:
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// |num_nonzero_coeffs| is the number of non-zero coefficients,
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// |nonzero_coeffs|. They are assumed to be uniformly distributed every
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// |sparsity| samples and with an initial |offset|. The rest of the filter
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// coefficients will be assumed zeros. For example, with sparsity = 3, and
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// offset = 1 the filter coefficients will be:
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// B = [0 coeffs[0] 0 0 coeffs[1] 0 0 coeffs[2] ... ]
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// All initial state values will be zeros.
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SparseFIRFilter(const float* nonzero_coeffs,
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size_t num_nonzero_coeffs,
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size_t sparsity,
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size_t offset);
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~SparseFIRFilter();
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// Filters the |in| data supplied.
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// |out| must be previously allocated and it must be at least of |length|.
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void Filter(const float* in, size_t length, float* out);
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private:
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const size_t sparsity_;
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const size_t offset_;
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const std::vector<float> nonzero_coeffs_;
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std::vector<float> state_;
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RTC_DISALLOW_COPY_AND_ASSIGN(SparseFIRFilter);
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};
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} // namespace webrtc
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#endif // COMMON_AUDIO_SPARSE_FIR_FILTER_H_
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