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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 #ifndef WEBRTC_MODULES_AUDIO_CONFERENCE_MIXER_INCLUDE_AUDIO_CONFERENCE_MIXER_H_
     12 #define WEBRTC_MODULES_AUDIO_CONFERENCE_MIXER_INCLUDE_AUDIO_CONFERENCE_MIXER_H_
     13 
     14 #include "webrtc/modules/audio_conference_mixer/include/audio_conference_mixer_defines.h"
     15 #include "webrtc/modules/include/module.h"
     16 #include "webrtc/modules/include/module_common_types.h"
     17 
     18 namespace webrtc {
     19 class AudioMixerOutputReceiver;
     20 class MixerParticipant;
     21 class Trace;
     22 
     23 class AudioConferenceMixer : public Module
     24 {
     25 public:
     26     enum {kMaximumAmountOfMixedParticipants = 3};
     27     enum Frequency
     28     {
     29         kNbInHz           = 8000,
     30         kWbInHz           = 16000,
     31         kSwbInHz          = 32000,
     32         kFbInHz           = 48000,
     33         kLowestPossible   = -1,
     34         kDefaultFrequency = kWbInHz
     35     };
     36 
     37     // Factory method. Constructor disabled.
     38     static AudioConferenceMixer* Create(int id);
     39     virtual ~AudioConferenceMixer() {}
     40 
     41     // Module functions
     42     int64_t TimeUntilNextProcess() override = 0;
     43     int32_t Process() override = 0;
     44 
     45     // Register/unregister a callback class for receiving the mixed audio.
     46     virtual int32_t RegisterMixedStreamCallback(
     47         AudioMixerOutputReceiver* receiver) = 0;
     48     virtual int32_t UnRegisterMixedStreamCallback() = 0;
     49 
     50     // Add/remove participants as candidates for mixing.
     51     virtual int32_t SetMixabilityStatus(MixerParticipant* participant,
     52                                         bool mixable) = 0;
     53     // Returns true if a participant is a candidate for mixing.
     54     virtual bool MixabilityStatus(
     55         const MixerParticipant& participant) const = 0;
     56 
     57     // Inform the mixer that the participant should always be mixed and not
     58     // count toward the number of mixed participants. Note that a participant
     59     // must have been added to the mixer (by calling SetMixabilityStatus())
     60     // before this function can be successfully called.
     61     virtual int32_t SetAnonymousMixabilityStatus(
     62         MixerParticipant* participant, bool mixable) = 0;
     63     // Returns true if the participant is mixed anonymously.
     64     virtual bool AnonymousMixabilityStatus(
     65         const MixerParticipant& participant) const = 0;
     66 
     67     // Set the minimum sampling frequency at which to mix. The mixing algorithm
     68     // may still choose to mix at a higher samling frequency to avoid
     69     // downsampling of audio contributing to the mixed audio.
     70     virtual int32_t SetMinimumMixingFrequency(Frequency freq) = 0;
     71 
     72 protected:
     73     AudioConferenceMixer() {}
     74 };
     75 }  // namespace webrtc
     76 
     77 #endif // WEBRTC_MODULES_AUDIO_CONFERENCE_MIXER_INCLUDE_AUDIO_CONFERENCE_MIXER_H_
     78