webrtc / src / ab9ed5c305ba0fc9dd5edb7625575d97ea881ba8 / . / modules / audio_coding / neteq / cross_correlation.h

/* | |

* 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 <stddef.h> | |

#include <stdint.h> | |

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_ |