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The Tor Browser
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voip_base.h (4798B)

      1 /*
      2 *  Copyright (c) 2020 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 API_VOIP_VOIP_BASE_H_
     12 #define API_VOIP_VOIP_BASE_H_
     13 
     14 #include <cstdint>
     15 #include <optional>
     16 
     17 #include "absl/base/attributes.h"
     18 
     19 namespace webrtc {
     20 
     21 class Transport;
     22 
     23 // VoipBase interface
     24 //
     25 // VoipBase provides a management interface on a media session using a
     26 // concept called 'channel'.  A channel represents an interface handle
     27 // for application to request various media session operations.  This
     28 // notion of channel is used throughout other interfaces as well.
     29 //
     30 // Underneath the interface, a channel id is mapped into an audio session
     31 // object that is capable of sending and receiving a single RTP stream with
     32 // another media endpoint.  It's possible to create and use multiple active
     33 // channels simultaneously which would mean that particular application
     34 // session has RTP streams with multiple remote endpoints.
     35 //
     36 // A typical example for the usage context is outlined in VoipEngine
     37 // header file.
     38 
     39 enum class ChannelId : int {};
     40 
     41 enum class ABSL_MUST_USE_RESULT VoipResult {
     42  // kOk indicates the function was successfully invoked with no error.
     43  kOk,
     44  // kInvalidArgument indicates the caller specified an invalid argument, such
     45  // as an invalid ChannelId.
     46  kInvalidArgument,
     47  // kFailedPrecondition indicates that the operation was failed due to not
     48  // satisfying prerequisite such as not setting codec type before sending.
     49  kFailedPrecondition,
     50  // kInternal is used to indicate various internal failures that are not the
     51  // caller's fault. Further detail is commented on each function that uses this
     52  // return value.
     53  kInternal,
     54 };
     55 
     56 class VoipBase {
     57 public:
     58  // Creates a channel.
     59  // Each channel handle maps into one audio media session where each has
     60  // its own separate module for send/receive rtp packet with one peer.
     61  // Caller must set `transport`, Transport callback pointer to
     62  // receive rtp/rtcp packets from corresponding media session in VoIP engine.
     63  // VoipEngine framework expects applications to handle network I/O directly
     64  // and injection for incoming RTP from remote endpoint is handled via
     65  // VoipNetwork interface. `local_ssrc` is optional and when local_ssrc is not
     66  // set, some random value will be used by voip engine.
     67  // Returns a ChannelId created for caller to handle subsequent Channel
     68  // operations.
     69  virtual ChannelId CreateChannel(Transport* transport,
     70                                  std::optional<uint32_t> local_ssrc) = 0;
     71 
     72  // Releases `channel_id` that no longer has any use.
     73  // Returns following VoipResult;
     74  //  kOk - `channel_id` is released.
     75  //  kInvalidArgument - `channel_id` is invalid.
     76  //  kInternal - Fails to stop audio output device.
     77  virtual VoipResult ReleaseChannel(ChannelId channel_id) = 0;
     78 
     79  // Starts sending on `channel_id`. This starts microphone if not started yet.
     80  // Returns following VoipResult;
     81  //  kOk - Channel successfully started to send.
     82  //  kInvalidArgument - `channel_id` is invalid.
     83  //  kFailedPrecondition - Missing prerequisite on VoipCodec::SetSendCodec.
     84  //  kInternal - initialization has failed on selected microphone.
     85  virtual VoipResult StartSend(ChannelId channel_id) = 0;
     86 
     87  // Stops sending on `channel_id`. If this is the last active channel, it will
     88  // stop microphone input from underlying audio platform layer.
     89  // Returns following VoipResult;
     90  //  kOk - Channel successfully stopped to send.
     91  //  kInvalidArgument - `channel_id` is invalid.
     92  //  kInternal - Failed to stop the active microphone device.
     93  virtual VoipResult StopSend(ChannelId channel_id) = 0;
     94 
     95  // Starts playing on speaker device for `channel_id`.
     96  // This will start underlying platform speaker device if not started.
     97  // Returns following VoipResult;
     98  //  kOk - Channel successfully started to play out.
     99  //  kInvalidArgument - `channel_id` is invalid.
    100  //  kFailedPrecondition - Missing prerequisite on VoipCodec::SetReceiveCodecs.
    101  //  kInternal - Failed to initializate the selected speaker device.
    102  virtual VoipResult StartPlayout(ChannelId channel_id) = 0;
    103 
    104  // Stops playing on speaker device for `channel_id`.
    105  // Returns following VoipResult;
    106  //  kOk - Channel successfully stopped t play out.
    107  //  kInvalidArgument - `channel_id` is invalid.
    108  virtual VoipResult StopPlayout(ChannelId channel_id) = 0;
    109 
    110 protected:
    111  virtual ~VoipBase() = default;
    112 };
    113 
    114 }  // namespace webrtc
    115 
    116 #endif  // API_VOIP_VOIP_BASE_H_