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_VIDEO_TRACK_H_ 6#define PPAPI_CPP_MEDIA_STREAM_VIDEO_TRACK_H_ 7 8#include <string> 9 10#include "ppapi/c/ppb_media_stream_video_track.h" 11#include "ppapi/cpp/resource.h" 12#include "ppapi/cpp/var.h" 13 14/// @file 15/// This file defines the <code>MediaStreamVideoTrack</code> interface for a 16/// video source resource, which receives video frames from a MediaStream video 17/// track in the browser. 18 19namespace pp { 20 21class VideoFrame; 22class CompletionCallback; 23template <typename T> class CompletionCallbackWithOutput; 24 25/// The <code>MediaStreamVideoTrack</code> class contains methods for 26/// receiving video frames from a MediaStream video track in the browser. 27class MediaStreamVideoTrack : public Resource { 28 public: 29 /// Default constructor for creating an is_null() 30 /// <code>MediaStreamVideoTrack</code> object. 31 MediaStreamVideoTrack(); 32 33 /// The copy constructor for <code>MediaStreamVideoTrack</code>. 34 /// 35 /// @param[in] other A reference to a <code>MediaStreamVideoTrack</code>. 36 MediaStreamVideoTrack(const MediaStreamVideoTrack& other); 37 38 /// Constructs a <code>MediaStreamVideoTrack</code> from 39 /// a <code>Resource</code>. 40 /// 41 /// @param[in] resource A <code>PPB_MediaStreamVideoTrack</code> resource. 42 explicit MediaStreamVideoTrack(const Resource& resource); 43 44 /// Constructs a <code>MediaStreamVideoTrack</code> that outputs given frames 45 /// to a new video track, which will be consumed by Javascript. 46 explicit MediaStreamVideoTrack(const InstanceHandle& instance); 47 48 /// A constructor used when you have received a <code>PP_Resource</code> as a 49 /// return value that has had 1 ref added for you. 50 /// 51 /// @param[in] resource A <code>PPB_MediaStreamVideoTrack</code> resource. 52 MediaStreamVideoTrack(PassRef, PP_Resource resource); 53 54 ~MediaStreamVideoTrack(); 55 56 /// Configures underlying frame buffers for incoming frames. 57 /// If the application doesn't want to drop frames, then the 58 /// <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES</code> should be 59 /// chosen such that inter-frame processing time variability won't overrun the 60 /// input buffer. If the buffer is overfilled, then frames will be dropped. 61 /// The application can detect this by examining the timestamp on returned 62 /// frames. If some attributes are not specified, default values will be used 63 /// for those unspecified attributes. If <code>Configure()</code> is not 64 /// called, default settings will be used. 65 /// Example usage from plugin code: 66 /// @code 67 /// int32_t attribs[] = { 68 /// PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES, 4, 69 /// PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE}; 70 /// track.Configure(attribs, callback); 71 /// @endcode 72 /// 73 /// @param[in] attrib_list A list of attribute name-value pairs in which each 74 /// attribute is immediately followed by the corresponding desired value. 75 /// The list is terminated by 76 /// <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE</code>. 77 /// @param[in] callback A <code>CompletionCallback</code> to be called upon 78 /// completion of <code>Configure()</code>. 79 /// 80 /// @return An int32_t containing a result code from <code>pp_errors.h</code>. 81 /// Returns <code>PP_ERROR_INPROGRESS</code> if there is a pending call of 82 /// <code>Configure()</code> or <code>GetFrame()</code>, or the plugin 83 /// holds some frames which are not recycled with <code>RecycleFrame()</code>. 84 /// If an error is returned, all attributes and the underlying buffer will not 85 /// be changed. 86 int32_t Configure(const int32_t attributes[], 87 const CompletionCallback& callback); 88 89 /// Gets attribute value for a given attribute name. 90 /// 91 /// @param[in] attrib A <code>PP_MediaStreamVideoTrack_Attrib</code> for 92 /// querying. 93 /// @param[out] value A int32_t for storing the attribute value. 94 /// 95 /// @return An int32_t containing a result code from <code>pp_errors.h</code>. 96 int32_t GetAttrib(PP_MediaStreamVideoTrack_Attrib attrib, 97 int32_t* value); 98 99 /// Returns the track ID of the underlying MediaStream video track. 100 std::string GetId() const; 101 102 /// Checks whether the underlying MediaStream track has ended. 103 /// Calls to GetFrame while the track has ended are safe to make and will 104 /// complete, but will fail. 105 bool HasEnded() const; 106 107 /// Gets the next video frame from the MediaStream track. 108 /// If internal processing is slower than the incoming frame rate, new frames 109 /// will be dropped from the incoming stream. Once the input buffer is full, 110 /// frames will be dropped until <code>RecycleFrame()</code> is called to free 111 /// a spot for another frame to be buffered. 112 /// If there are no frames in the input buffer, 113 /// <code>PP_OK_COMPLETIONPENDING</code> will be returned immediately and the 114 /// <code>callback</code> will be called when a new frame is received or some 115 /// error happens. 116 /// 117 /// @param[in] callback A <code>CompletionCallbackWithOutput</code> to be 118 /// called upon completion of <code>GetFrame()</code>. If success, 119 /// a VideoFrame will be passed into the completion callback function. 120 /// 121 /// @return An int32_t containing a result code from <code>pp_errors.h</code>. 122 /// Returns PP_ERROR_NOMEMORY if <code>max_buffered_frames</code> frames 123 /// buffer was not allocated successfully. 124 int32_t GetFrame( 125 const CompletionCallbackWithOutput<VideoFrame>& callback); 126 127 /// Recycles a frame returned by <code>GetFrame()</code>, so the track can 128 /// reuse the underlying buffer of this frame. And the frame will become 129 /// invalid. The caller should release all references it holds to 130 /// <code>frame</code> and not use it anymore. 131 /// 132 /// @param[in] frame A VideoFrame returned by <code>GetFrame()</code>. 133 /// 134 /// @return An int32_t containing a result code from <code>pp_errors.h</code>. 135 int32_t RecycleFrame(const VideoFrame& frame); 136 137 /// Closes the MediaStream video track, and disconnects it from video source. 138 /// After calling <code>Close()</code>, no new frames will be received. 139 void Close(); 140 141 // Gets a free frame for output. The frame is allocated by 142 // <code>Configure()</code>. The caller should fill it with frame data, and 143 // then use |PutFrame()| to send the frame back. 144 int32_t GetEmptyFrame( 145 const CompletionCallbackWithOutput<VideoFrame>& callback); 146 147 // Sends a frame returned by |GetEmptyFrame()| to the output track. 148 // After this function, the |frame| should not be used anymore and the 149 // caller should release the reference that it holds. 150 int32_t PutFrame(const VideoFrame& frame); 151 152 /// Checks whether a <code>Resource</code> is a MediaStream video track, 153 /// to test whether it is appropriate for use with the 154 /// <code>MediaStreamVideoTrack</code> constructor. 155 /// 156 /// @param[in] resource A <code>Resource</code> to test. 157 /// 158 /// @return True if <code>resource</code> is a MediaStream video track. 159 static bool IsMediaStreamVideoTrack(const Resource& resource); 160}; 161 162} // namespace pp 163 164#endif // PPAPI_CPP_MEDIA_STREAM_VIDEO_TRACK_H_ 165