1 // Copyright 2014 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #ifndef PPAPI_CPP_MEDIA_STREAM_VIDEO_TRACK_H_
6 #define PPAPI_CPP_MEDIA_STREAM_VIDEO_TRACK_H_
12 #include "ppapi/c/ppb_media_stream_video_track.h"
13 #include "ppapi/cpp/resource.h"
14 #include "ppapi/cpp/var.h"
17 /// This file defines the <code>MediaStreamVideoTrack</code> interface for a
18 /// video source resource, which receives video frames from a MediaStream video
19 /// track in the browser.
24 class CompletionCallback;
25 template <typename T> class CompletionCallbackWithOutput;
27 /// The <code>MediaStreamVideoTrack</code> class contains methods for
28 /// receiving video frames from a MediaStream video track in the browser.
29 class MediaStreamVideoTrack : public Resource {
31 /// Default constructor for creating an is_null()
32 /// <code>MediaStreamVideoTrack</code> object.
33 MediaStreamVideoTrack();
35 /// The copy constructor for <code>MediaStreamVideoTrack</code>.
37 /// @param[in] other A reference to a <code>MediaStreamVideoTrack</code>.
38 MediaStreamVideoTrack(const MediaStreamVideoTrack& other);
40 /// Constructs a <code>MediaStreamVideoTrack</code> from
41 /// a <code>Resource</code>.
43 /// @param[in] resource A <code>PPB_MediaStreamVideoTrack</code> resource.
44 explicit MediaStreamVideoTrack(const Resource& resource);
46 /// Constructs a <code>MediaStreamVideoTrack</code> that outputs given frames
47 /// to a new video track, which will be consumed by Javascript.
48 explicit MediaStreamVideoTrack(const InstanceHandle& instance);
50 /// A constructor used when you have received a <code>PP_Resource</code> as a
51 /// return value that has had 1 ref added for you.
53 /// @param[in] resource A <code>PPB_MediaStreamVideoTrack</code> resource.
54 MediaStreamVideoTrack(PassRef, PP_Resource resource);
56 ~MediaStreamVideoTrack();
58 /// Configures underlying frame buffers for incoming frames.
59 /// If the application doesn't want to drop frames, then the
60 /// <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES</code> should be
61 /// chosen such that inter-frame processing time variability won't overrun the
62 /// input buffer. If the buffer is overfilled, then frames will be dropped.
63 /// The application can detect this by examining the timestamp on returned
64 /// frames. If some attributes are not specified, default values will be used
65 /// for those unspecified attributes. If <code>Configure()</code> is not
66 /// called, default settings will be used.
67 /// Example usage from plugin code:
69 /// int32_t attribs[] = {
70 /// PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES, 4,
71 /// PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE};
72 /// track.Configure(attribs, callback);
75 /// @param[in] attrib_list A list of attribute name-value pairs in which each
76 /// attribute is immediately followed by the corresponding desired value.
77 /// The list is terminated by
78 /// <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE</code>.
79 /// @param[in] callback A <code>CompletionCallback</code> to be called upon
80 /// completion of <code>Configure()</code>.
82 /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
83 /// Returns <code>PP_ERROR_INPROGRESS</code> if there is a pending call of
84 /// <code>Configure()</code> or <code>GetFrame()</code>, or the plugin
85 /// holds some frames which are not recycled with <code>RecycleFrame()</code>.
86 /// If an error is returned, all attributes and the underlying buffer will not
88 int32_t Configure(const int32_t attributes[],
89 const CompletionCallback& callback);
91 /// Gets attribute value for a given attribute name.
93 /// @param[in] attrib A <code>PP_MediaStreamVideoTrack_Attrib</code> for
95 /// @param[out] value A int32_t for storing the attribute value.
97 /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
98 int32_t GetAttrib(PP_MediaStreamVideoTrack_Attrib attrib,
101 /// Returns the track ID of the underlying MediaStream video track.
102 std::string GetId() const;
104 /// Checks whether the underlying MediaStream track has ended.
105 /// Calls to GetFrame while the track has ended are safe to make and will
106 /// complete, but will fail.
107 bool HasEnded() const;
109 /// Gets the next video frame from the MediaStream track.
110 /// If internal processing is slower than the incoming frame rate, new frames
111 /// will be dropped from the incoming stream. Once the input buffer is full,
112 /// frames will be dropped until <code>RecycleFrame()</code> is called to free
113 /// a spot for another frame to be buffered.
114 /// If there are no frames in the input buffer,
115 /// <code>PP_OK_COMPLETIONPENDING</code> will be returned immediately and the
116 /// <code>callback</code> will be called when a new frame is received or some
119 /// @param[in] callback A <code>CompletionCallbackWithOutput</code> to be
120 /// called upon completion of <code>GetFrame()</code>. If success,
121 /// a VideoFrame will be passed into the completion callback function.
123 /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
124 /// Returns PP_ERROR_NOMEMORY if <code>max_buffered_frames</code> frames
125 /// buffer was not allocated successfully.
127 const CompletionCallbackWithOutput<VideoFrame>& callback);
129 /// Recycles a frame returned by <code>GetFrame()</code>, so the track can
130 /// reuse the underlying buffer of this frame. And the frame will become
131 /// invalid. The caller should release all references it holds to
132 /// <code>frame</code> and not use it anymore.
134 /// @param[in] frame A VideoFrame returned by <code>GetFrame()</code>.
136 /// @return An int32_t containing a result code from <code>pp_errors.h</code>.
137 int32_t RecycleFrame(const VideoFrame& frame);
139 /// Closes the MediaStream video track, and disconnects it from video source.
140 /// After calling <code>Close()</code>, no new frames will be received.
143 // Gets a free frame for output. The frame is allocated by
144 // <code>Configure()</code>. The caller should fill it with frame data, and
145 // then use |PutFrame()| to send the frame back.
146 int32_t GetEmptyFrame(
147 const CompletionCallbackWithOutput<VideoFrame>& callback);
149 // Sends a frame returned by |GetEmptyFrame()| to the output track.
150 // After this function, the |frame| should not be used anymore and the
151 // caller should release the reference that it holds.
152 int32_t PutFrame(const VideoFrame& frame);
154 /// Checks whether a <code>Resource</code> is a MediaStream video track,
155 /// to test whether it is appropriate for use with the
156 /// <code>MediaStreamVideoTrack</code> constructor.
158 /// @param[in] resource A <code>Resource</code> to test.
160 /// @return True if <code>resource</code> is a MediaStream video track.
161 static bool IsMediaStreamVideoTrack(const Resource& resource);
166 #endif // PPAPI_CPP_MEDIA_STREAM_VIDEO_TRACK_H_