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0b489303d2
Bug: webrtc:12338 Change-Id: I85bff694dd2ead83c939c4d1945eff82e1296001 No-Presubmit: True Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/227161 Commit-Queue: Artem Titov <titovartem@webrtc.org> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Cr-Commit-Position: refs/heads/master@{#34690}
68 lines
2.4 KiB
C++
68 lines
2.4 KiB
C++
/*
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* Copyright (c) 2013 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 MODULES_AUDIO_PROCESSING_TRANSIENT_DYADIC_DECIMATOR_H_
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#define MODULES_AUDIO_PROCESSING_TRANSIENT_DYADIC_DECIMATOR_H_
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#include <cstdlib>
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// Provides a set of static methods to perform dyadic decimations.
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namespace webrtc {
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// Returns the proper length of the output buffer that you should use for the
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// given `in_length` and decimation `odd_sequence`.
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// Return -1 on error.
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inline size_t GetOutLengthToDyadicDecimate(size_t in_length,
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bool odd_sequence) {
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size_t out_length = in_length / 2;
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if (in_length % 2 == 1 && !odd_sequence) {
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++out_length;
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}
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return out_length;
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}
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// Performs a dyadic decimation: removes every odd/even member of a sequence
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// halving its overall length.
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// Arguments:
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// in: array of `in_length`.
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// odd_sequence: If false, the odd members will be removed (1, 3, 5, ...);
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// if true, the even members will be removed (0, 2, 4, ...).
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// out: array of `out_length`. `out_length` must be large enough to
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// hold the decimated output. The necessary length can be provided by
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// GetOutLengthToDyadicDecimate().
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// Must be previously allocated.
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// Returns the number of output samples, -1 on error.
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template <typename T>
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static size_t DyadicDecimate(const T* in,
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size_t in_length,
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bool odd_sequence,
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T* out,
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size_t out_length) {
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size_t half_length = GetOutLengthToDyadicDecimate(in_length, odd_sequence);
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if (!in || !out || in_length <= 0 || out_length < half_length) {
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return 0;
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}
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size_t output_samples = 0;
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size_t index_adjustment = odd_sequence ? 1 : 0;
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for (output_samples = 0; output_samples < half_length; ++output_samples) {
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out[output_samples] = in[output_samples * 2 + index_adjustment];
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}
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return output_samples;
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}
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} // namespace webrtc
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#endif // MODULES_AUDIO_PROCESSING_TRANSIENT_DYADIC_DECIMATOR_H_
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