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      1 /*
      2  *  Copyright (c) 2011 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 
     12 /*
     13  * A wrapper for resampling a numerous amount of sampling combinations.
     14  */
     15 
     16 #ifndef WEBRTC_RESAMPLER_RESAMPLER_H_
     17 #define WEBRTC_RESAMPLER_RESAMPLER_H_
     18 
     19 #include "webrtc/typedefs.h"
     20 
     21 namespace webrtc
     22 {
     23 
     24 // TODO(andrew): the implementation depends on the exact values of this enum.
     25 // It should be rewritten in a less fragile way.
     26 enum ResamplerType
     27 {
     28     // 4 MSB = Number of channels
     29     // 4 LSB = Synchronous or asynchronous
     30 
     31     kResamplerSynchronous = 0x10,
     32     kResamplerAsynchronous = 0x11,
     33     kResamplerSynchronousStereo = 0x20,
     34     kResamplerAsynchronousStereo = 0x21,
     35     kResamplerInvalid = 0xff
     36 };
     37 
     38 // TODO(andrew): doesn't need to be part of the interface.
     39 enum ResamplerMode
     40 {
     41     kResamplerMode1To1,
     42     kResamplerMode1To2,
     43     kResamplerMode1To3,
     44     kResamplerMode1To4,
     45     kResamplerMode1To6,
     46     kResamplerMode1To12,
     47     kResamplerMode2To3,
     48     kResamplerMode2To11,
     49     kResamplerMode4To11,
     50     kResamplerMode8To11,
     51     kResamplerMode11To16,
     52     kResamplerMode11To32,
     53     kResamplerMode2To1,
     54     kResamplerMode3To1,
     55     kResamplerMode4To1,
     56     kResamplerMode6To1,
     57     kResamplerMode12To1,
     58     kResamplerMode3To2,
     59     kResamplerMode11To2,
     60     kResamplerMode11To4,
     61     kResamplerMode11To8
     62 };
     63 
     64 class Resampler
     65 {
     66 
     67 public:
     68     Resampler();
     69     // TODO(andrew): use an init function instead.
     70     Resampler(int inFreq, int outFreq, ResamplerType type);
     71     ~Resampler();
     72 
     73     // Reset all states
     74     int Reset(int inFreq, int outFreq, ResamplerType type);
     75 
     76     // Reset all states if any parameter has changed
     77     int ResetIfNeeded(int inFreq, int outFreq, ResamplerType type);
     78 
     79     // Synchronous resampling, all output samples are written to samplesOut
     80     int Push(const int16_t* samplesIn, int lengthIn, int16_t* samplesOut,
     81              int maxLen, int &outLen);
     82 
     83     // Asynchronous resampling, input
     84     int Insert(int16_t* samplesIn, int lengthIn);
     85 
     86     // Asynchronous resampling output, remaining samples are buffered
     87     int Pull(int16_t* samplesOut, int desiredLen, int &outLen);
     88 
     89 private:
     90     // Generic pointers since we don't know what states we'll need
     91     void* state1_;
     92     void* state2_;
     93     void* state3_;
     94 
     95     // Storage if needed
     96     int16_t* in_buffer_;
     97     int16_t* out_buffer_;
     98     int in_buffer_size_;
     99     int out_buffer_size_;
    100     int in_buffer_size_max_;
    101     int out_buffer_size_max_;
    102 
    103     // State
    104     int my_in_frequency_khz_;
    105     int my_out_frequency_khz_;
    106     ResamplerMode my_mode_;
    107     ResamplerType my_type_;
    108 
    109     // Extra instance for stereo
    110     Resampler* slave_left_;
    111     Resampler* slave_right_;
    112 };
    113 
    114 }  // namespace webrtc
    115 
    116 #endif // WEBRTC_RESAMPLER_RESAMPLER_H_
    117