Line data    Source code

       1             : /*
       2             :  *  Copyright (c) 2014 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             : 
      11             : #ifndef WEBRTC_COMMON_AUDIO_FIR_FILTER_H_
      12             : #define WEBRTC_COMMON_AUDIO_FIR_FILTER_H_
      13             : 
      14             : #include <string.h>
      15             : 
      16             : namespace webrtc {
      17             : 
      18             : // Finite Impulse Response filter using floating-point arithmetic.
      19           0 : class FIRFilter {
      20             :  public:
      21             :   // Creates a filter with the given coefficients. All initial state values will
      22             :   // be zeros.
      23             :   // The length of the chunks fed to the filter should never be greater than
      24             :   // |max_input_length|. This is needed because, when vectorizing it is
      25             :   // necessary to concatenate the input after the state, and resizing this array
      26             :   // dynamically is expensive.
      27             :   static FIRFilter* Create(const float* coefficients,
      28             :                            size_t coefficients_length,
      29             :                            size_t max_input_length);
      30             : 
      31           0 :   virtual ~FIRFilter() {}
      32             : 
      33             :   // Filters the |in| data supplied.
      34             :   // |out| must be previously allocated and it must be at least of |length|.
      35             :   virtual void Filter(const float* in, size_t length, float* out) = 0;
      36             : };
      37             : 
      38             : }  // namespace webrtc
      39             : 
      40             : #endif  // WEBRTC_COMMON_AUDIO_FIR_FILTER_H_