tor-browser

The Tor Browser
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dtmf_buffer.h (3322B)

      1 /*
      2 *  Copyright (c) 2012 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 MODULES_AUDIO_CODING_NETEQ_DTMF_BUFFER_H_
     12 #define MODULES_AUDIO_CODING_NETEQ_DTMF_BUFFER_H_
     13 
     14 #include <stddef.h>
     15 #include <stdint.h>
     16 
     17 #include <list>
     18 
     19 namespace webrtc {
     20 
     21 struct DtmfEvent {
     22  uint32_t timestamp;
     23  int event_no;
     24  int volume;
     25  int duration;
     26  bool end_bit;
     27 
     28  // Constructors
     29  DtmfEvent()
     30      : timestamp(0), event_no(0), volume(0), duration(0), end_bit(false) {}
     31  DtmfEvent(uint32_t ts, int ev, int vol, int dur, bool end)
     32      : timestamp(ts), event_no(ev), volume(vol), duration(dur), end_bit(end) {}
     33 };
     34 
     35 // This is the buffer holding DTMF events while waiting for them to be played.
     36 class DtmfBuffer {
     37 public:
     38  enum BufferReturnCodes {
     39    kOK = 0,
     40    kInvalidPointer,
     41    kPayloadTooShort,
     42    kInvalidEventParameters,
     43    kInvalidSampleRate
     44  };
     45 
     46  // Set up the buffer for use at sample rate `fs_hz`.
     47  explicit DtmfBuffer(int fs_hz);
     48 
     49  virtual ~DtmfBuffer();
     50 
     51  DtmfBuffer(const DtmfBuffer&) = delete;
     52  DtmfBuffer& operator=(const DtmfBuffer&) = delete;
     53 
     54  // Flushes the buffer.
     55  virtual void Flush();
     56 
     57  // Static method to parse 4 bytes from `payload` as a DTMF event (RFC 4733)
     58  // and write the parsed information into the struct `event`. Input variable
     59  // `rtp_timestamp` is simply copied into the struct.
     60  static int ParseEvent(uint32_t rtp_timestamp,
     61                        const uint8_t* payload,
     62                        size_t payload_length_bytes,
     63                        DtmfEvent* event);
     64 
     65  // Inserts `event` into the buffer. The method looks for a matching event and
     66  // merges the two if a match is found.
     67  virtual int InsertEvent(const DtmfEvent& event);
     68 
     69  // Checks if a DTMF event should be played at time `current_timestamp`. If so,
     70  // the method returns true; otherwise false. The parameters of the event to
     71  // play will be written to `event`.
     72  virtual bool GetEvent(uint32_t current_timestamp, DtmfEvent* event);
     73 
     74  // Number of events in the buffer.
     75  virtual size_t Length() const;
     76 
     77  virtual bool Empty() const;
     78 
     79  // Set a new sample rate.
     80  virtual int SetSampleRate(int fs_hz);
     81 
     82 private:
     83  typedef std::list<DtmfEvent> DtmfList;
     84 
     85  int max_extrapolation_samples_;
     86  int frame_len_samples_;  // TODO(hlundin): Remove this later.
     87 
     88  // Compares two events and returns true if they are the same.
     89  static bool SameEvent(const DtmfEvent& a, const DtmfEvent& b);
     90 
     91  // Merges `event` to the event pointed out by `it`. The method checks that
     92  // the two events are the same (using the SameEvent method), and merges them
     93  // if that was the case, returning true. If the events are not the same, false
     94  // is returned.
     95  bool MergeEvents(DtmfList::iterator it, const DtmfEvent& event);
     96 
     97  // Method used by the sort algorithm to rank events in the buffer.
     98  static bool CompareEvents(const DtmfEvent& a, const DtmfEvent& b);
     99 
    100  DtmfList buffer_;
    101 };
    102 
    103 }  // namespace webrtc
    104 #endif  // MODULES_AUDIO_CODING_NETEQ_DTMF_BUFFER_H_