Line data    Source code

       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_API_AUDIO_AUDIO_MIXER_H_
      12             : #define WEBRTC_API_AUDIO_AUDIO_MIXER_H_
      13             : 
      14             : #include <memory>
      15             : 
      16             : #include "webrtc/base/refcount.h"
      17             : #include "webrtc/modules/include/module_common_types.h"
      18             : 
      19             : namespace webrtc {
      20             : 
      21             : // WORK IN PROGRESS
      22             : // This class is under development and is not yet intended for for use outside
      23             : // of WebRtc/Libjingle.
      24           0 : class AudioMixer : public rtc::RefCountInterface {
      25             :  public:
      26             :   // A callback class that all mixer participants must inherit from/implement.
      27           0 :   class Source {
      28             :    public:
      29             :     enum class AudioFrameInfo {
      30             :       kNormal,  // The samples in audio_frame are valid and should be used.
      31             :       kMuted,   // The samples in audio_frame should not be used, but
      32             :                 // should be implicitly interpreted as zero. Other
      33             :                 // fields in audio_frame may be read and should
      34             :                 // contain meaningful values.
      35             :       kError,   // The audio_frame will not be used.
      36             :     };
      37             : 
      38             :     // Overwrites |audio_frame|. The data_ field is overwritten with
      39             :     // 10 ms of new audio (either 1 or 2 interleaved channels) at
      40             :     // |sample_rate_hz|. All fields in |audio_frame| must be updated.
      41             :     virtual AudioFrameInfo GetAudioFrameWithInfo(int sample_rate_hz,
      42             :                                                  AudioFrame* audio_frame) = 0;
      43             : 
      44             :     // A way for a mixer implementation to distinguish participants.
      45             :     virtual int Ssrc() const = 0;
      46             : 
      47             :     // A way for this source to say that GetAudioFrameWithInfo called
      48             :     // with this sample rate or higher will not cause quality loss.
      49             :     virtual int PreferredSampleRate() const = 0;
      50             : 
      51           0 :     virtual ~Source() {}
      52             :   };
      53             : 
      54             :   // Returns true if adding was successful. A source is never added
      55             :   // twice. Addition and removal can happen on different threads.
      56             :   virtual bool AddSource(Source* audio_source) = 0;
      57             : 
      58             :   // Removal is never attempted if a source has not been successfully
      59             :   // added to the mixer.
      60             :   virtual void RemoveSource(Source* audio_source) = 0;
      61             : 
      62             :   // Performs mixing by asking registered audio sources for audio. The
      63             :   // mixed result is placed in the provided AudioFrame. This method
      64             :   // will only be called from a single thread. The channels argument
      65             :   // specifies the number of channels of the mix result. The mixer
      66             :   // should mix at a rate that doesn't cause quality loss of the
      67             :   // sources' audio. The mixing rate is one of the rates listed in
      68             :   // AudioProcessing::NativeRate. All fields in
      69             :   // |audio_frame_for_mixing| must be updated.
      70             :   virtual void Mix(size_t number_of_channels,
      71             :                    AudioFrame* audio_frame_for_mixing) = 0;
      72             : 
      73             :  protected:
      74             :   // Since the mixer is reference counted, the destructor may be
      75             :   // called from any thread.
      76           0 :   ~AudioMixer() override {}
      77             : };
      78             : }  // namespace webrtc
      79             : 
      80             : #endif  // WEBRTC_API_AUDIO_AUDIO_MIXER_H_