1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef PPAPI_CPP_MEDIA_STREAM_AUDIO_TRACK_H_ 6 #define PPAPI_CPP_MEDIA_STREAM_AUDIO_TRACK_H_ 7 8 #include <string> 9 10 #include "ppapi/c/ppb_media_stream_audio_track.h" 11 #include "ppapi/cpp/resource.h" 12 #include "ppapi/cpp/var.h" 13 14 /// @file 15 /// This file defines the <code>MediaStreamAudioTrack</code> interface for an 16 /// audio source resource, which receives audio buffers from a MediaStream audio 17 /// track in the browser. 18 19 namespace pp { 20 21 class AudioBuffer; 22 class CompletionCallback; 23 template <typename T> class CompletionCallbackWithOutput; 24 25 /// The <code>MediaStreamAudioTrack</code> class contains methods for 26 /// receiving audio buffers from a MediaStream audio track in the browser. 27 class MediaStreamAudioTrack : public Resource { 28 public: 29 /// Default constructor for creating an is_null() 30 /// <code>MediaStreamAudioTrack</code> object. 31 MediaStreamAudioTrack(); 32 33 /// The copy constructor for <code>MediaStreamAudioTrack</code>. 34 /// 35 /// @param[in] other A reference to a <code>MediaStreamAudioTrack</code>. 36 MediaStreamAudioTrack(const MediaStreamAudioTrack& other); 37 38 /// Constructs a <code>MediaStreamAudioTrack</code> from 39 /// a <code>Resource</code>. 40 /// 41 /// @param[in] resource A <code>PPB_MediaStreamAudioTrack</code> resource. 42 explicit MediaStreamAudioTrack(const Resource& resource); 43 44 /// A constructor used when you have received a <code>PP_Resource</code> as a 45 /// return value that has had 1 ref added for you. 46 /// 47 /// @param[in] resource A <code>PPB_MediaStreamAudioTrack</code> resource. 48 MediaStreamAudioTrack(PassRef, PP_Resource resource); 49 50 ~MediaStreamAudioTrack(); 51 52 /// Configures underlying buffer buffers for incoming audio samples. 53 /// If the application doesn't want to drop samples, then the 54 /// <code>PP_MEDIASTREAMAUDIOTRACK_ATTRIB_BUFFERS</code> should be 55 /// chosen such that inter-buffer processing time variability won't overrun 56 /// all input buffers. If all buffers are filled, then samples will be 57 /// dropped. The application can detect this by examining the timestamp on 58 /// returned buffers. If <code>Configure()</code> is not called, default 59 /// settings will be used. Calls to Configure while the plugin holds 60 /// buffers will fail. 61 /// Example usage from plugin code: 62 /// @code 63 /// int32_t attribs[] = { 64 /// PP_MEDIASTREAMAUDIOTRACK_ATTRIB_BUFFERS, 4, 65 /// PP_MEDIASTREAMAUDIOTRACK_ATTRIB_DURATION, 10, 66 /// PP_MEDIASTREAMAUDIOTRACK_ATTRIB_NONE}; 67 /// track.Configure(attribs, callback); 68 /// @endcode 69 /// 70 /// @param[in] attrib_list A list of attribute name-value pairs in which each 71 /// attribute is immediately followed by the corresponding desired value. 72 /// The list is terminated by 73 /// <code>PP_MEDIASTREAMAUDIOTRACK_AUDIO_NONE</code>. 74 /// @param[in] callback A <code>CompletionCallback</code> to be called upon 75 /// completion of <code>Configure()</code>. 76 /// 77 /// @return An int32_t containing a result code from <code>pp_errors.h</code>. 78 int32_t Configure(const int32_t attributes[], 79 const CompletionCallback& callback); 80 81 /// Gets attribute value for a given attribute name. 82 /// 83 /// @param[in] attrib A <code>PP_MediaStreamAudioTrack_Attrib</code> for 84 /// querying. 85 /// @param[out] value A int32_t for storing the attribute value. 86 /// 87 /// @return An int32_t containing a result code from <code>pp_errors.h</code>. 88 int32_t GetAttrib(PP_MediaStreamAudioTrack_Attrib attrib, 89 int32_t* value); 90 91 /// Returns the track ID of the underlying MediaStream audio track. 92 std::string GetId() const; 93 94 /// Checks whether the underlying MediaStream track has ended. 95 /// Calls to GetBuffer while the track has ended are safe to make and will 96 /// complete, but will fail. 97 bool HasEnded() const; 98 99 /// Gets the next audio buffer from the MediaStream track. 100 /// If internal processing is slower than the incoming buffer rate, 101 /// new buffers will be dropped from the incoming stream. Once all buffers 102 /// are full, audio samples will be dropped until <code>RecycleBuffer()</code> 103 /// is called to free a spot for another buffer. 104 /// If there are no audio data in the input buffer, 105 /// <code>PP_OK_COMPLETIONPENDING</code> will be returned immediately and the 106 /// <code>callback</code> will be called when a new buffer of audio samples 107 /// is received or some error happens. 108 /// 109 /// @param[in] callback A <code>CompletionCallbackWithOutput</code> to be 110 /// called upon completion of <code>GetBuffer()</code>. If success, 111 /// an AudioBuffer will be passed into the completion callback function. 112 /// 113 /// @return An int32_t containing a result code from <code>pp_errors.h</code>. 114 int32_t GetBuffer( 115 const CompletionCallbackWithOutput<AudioBuffer>& callback); 116 117 /// Recycles a buffer returned by <code>GetBuffer()</code>, so the track can 118 /// reuse the buffer. And the buffer will become invalid. The caller should 119 /// release all references it holds to <code>buffer</code> and not use it 120 /// anymore. 121 /// 122 /// @param[in] buffer A AudioBuffer returned by <code>GetBuffer()</code>. 123 /// 124 /// @return An int32_t containing a result code from <code>pp_errors.h</code>. 125 int32_t RecycleBuffer(const AudioBuffer& buffer); 126 127 /// Closes the MediaStream audio track, and disconnects it from the audio 128 /// source. 129 /// After calling <code>Close()</code>, no new buffers will be received. 130 void Close(); 131 132 /// Checks whether a <code>Resource</code> is a MediaStream audio track, 133 /// to test whether it is appropriate for use with the 134 /// <code>MediaStreamAudioTrack</code> constructor. 135 /// 136 /// @param[in] resource A <code>Resource</code> to test. 137 /// 138 /// @return True if <code>resource</code> is a MediaStream audio track. 139 static bool IsMediaStreamAudioTrack(const Resource& resource); 140 }; 141 142 } // namespace pp 143 144 #endif // PPAPI_CPP_MEDIA_STREAM_AUDIO_TRACK_H_ 145