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 /* * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */ #ifndef MODULES_AUDIO_CODING_NETEQ_CROSS_CORRELATION_H_ #define MODULES_AUDIO_CODING_NETEQ_CROSS_CORRELATION_H_ #include #include namespace webrtc { // The function calculates the cross-correlation between two sequences // `sequence_1` and `sequence_2`. `sequence_1` is taken as reference, with // `sequence_1_length` as its length. `sequence_2` slides for the calculation of // cross-correlation. The result will be saved in `cross_correlation`. // `cross_correlation_length` correlation points are calculated. // The corresponding lag starts from 0, and increases with a step of // `cross_correlation_step`. The result is without normalization. To avoid // overflow, the result will be right shifted. The amount of shifts will be // returned. // // Input: // - sequence_1 : First sequence (reference). // - sequence_2 : Second sequence (sliding during calculation). // - sequence_1_length : Length of `sequence_1`. // - cross_correlation_length : Number of cross-correlations to calculate. // - cross_correlation_step : Step in the lag for the cross-correlation. // // Output: // - cross_correlation : The cross-correlation in Q(-right_shifts) // // Return: // Number of right shifts in cross_correlation. int CrossCorrelationWithAutoShift(const int16_t* sequence_1, const int16_t* sequence_2, size_t sequence_1_length, size_t cross_correlation_length, int cross_correlation_step, int32_t* cross_correlation); } // namespace webrtc #endif // MODULES_AUDIO_CODING_NETEQ_CROSS_CORRELATION_H_