ppapi/api/ppb_media_stream_video_track.idl

   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
   6 /**
   7  * Defines the <code>PPB_MediaStreamVideoTrack</code> interface. Used for
   8  * receiving video frames from a MediaStream video track in the browser.
   9  */
  10
  11 [generate_thunk]
  12
  13 label Chrome {
  14   [channel=dev] M34 = 0.1,
  15   M35 = 0.1
  16 };
  17
  18 /**
  19  * This enumeration contains video track attributes which are used by
  20  * <code>Configure()</code>.
  21  */
  22 enum PP_MediaStreamVideoTrack_Attrib {
  23   /**
  24    * Attribute list terminator.
  25    */
  26   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE = 0,
  27
  28   /**
  29    * The maximum number of frames to hold in the input buffer.
  30    * Note: this is only used as advisory; the browser may allocate more or fewer
  31    * based on available resources. How many frames to buffer depends on usage -
  32    * request at least 2 to make sure latency doesn't cause lost frames. If
  33    * the plugin expects to hold on to more than one frame at a time (e.g. to do
  34    * multi-frame processing), it should request that many more.
  35    * If this attribute is not specified or value 0 is specified for this
  36    * attribute, the default value will be used.
  37    */
  38   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES = 1,
  39
  40   /**
  41    * The width of video frames in pixels. It should be a multiple of 4.
  42    * If the specified size is different from the video source (webcam),
  43    * frames will be scaled to specified size.
  44    * If this attribute is not specified or value 0 is specified, the original
  45    * frame size of the video track will be used.
  46    *
  47    * Maximum value: 4096 (4K resolution).
  48    */
  49   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_WIDTH = 2,
  50
  51   /**
  52    * The height of video frames in pixels. It should be a multiple of 4.
  53    * If the specified size is different from the video source (webcam),
  54    * frames will be scaled to specified size.
  55    * If this attribute is not specified or value 0 is specified, the original
  56    * frame size of the video track will be used.
  57    *
  58    * Maximum value: 4096 (4K resolution).
  59    */
  60   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_HEIGHT = 3,
  61
  62   /**
  63    * The format of video frames. The attribute value is
  64    * a <code>PP_VideoFrame_Format</code>. If the specified format is different
  65    * from the video source (webcam), frames will be converted to specified
  66    * format.
  67    * If this attribute is not specified or value
  68    * <code>PP_VIDEOFRAME_FORMAT_UNKNOWN</code> is specified, the orignal frame
  69    * format of the video track will be used.
  70    */
  71   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_FORMAT = 4
  72 };
  73
  74 [version=0.1]
  75 interface PPB_MediaStreamVideoTrack {
  76   /**
  77    * Determines if a resource is a MediaStream video track resource.
  78    *
  79    * @param[in] resource The <code>PP_Resource</code> to test.
  80    *
  81    * @return A <code>PP_Bool</code> with <code>PP_TRUE</code> if the given
  82    * resource is a Mediastream video track resource or <code>PP_FALSE</code>
  83    * otherwise.
  84    */
  85   PP_Bool IsMediaStreamVideoTrack([in] PP_Resource resource);
  86
  87   /**
  88    * Configures underlying frame buffers for incoming frames.
  89    * If the application doesn't want to drop frames, then the
  90    * <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES</code> should be
  91    * chosen such that inter-frame processing time variability won't overrun the
  92    * input buffer. If the buffer is overfilled, then frames will be dropped.
  93    * The application can detect this by examining the timestamp on returned
  94    * frames. If some attributes are not specified, default values will be used
  95    * for those unspecified attributes. If <code>Configure()</code> is not
  96    * called, default settings will be used.
  97    * Example usage from plugin code:
  98    * @code
  99    * int32_t attribs[] = {
 100    *     PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES, 4,
 101    *     PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE};
 102    * track_if->Configure(track, attribs, callback);
 103    * @endcode
 104    *
 105    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
 106    * resource.
 107    * @param[in] attrib_list A list of attribute name-value pairs in which each
 108    * attribute is immediately followed by the corresponding desired value.
 109    * The list is terminated by
 110    * <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE</code>.
 111    * @param[in] callback <code>PP_CompletionCallback</code> to be called upon
 112    * completion of <code>Configure()</code>.
 113    *
 114    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
 115    * Returns <code>PP_ERROR_INPROGRESS</code> if there is a pending call of
 116    * <code>Configure()</code> or <code>GetFrame()</code>, or the plugin
 117    * holds some frames which are not recycled with <code>RecycleFrame()</code>.
 118    * If an error is returned, all attributes and the underlying buffer will not
 119    * be changed.
 120    */
 121   int32_t Configure([in] PP_Resource video_track,
 122                     [in] int32_t[] attrib_list,
 123                     [in] PP_CompletionCallback callback);
 124
 125   /**
 126    * Gets attribute value for a given attribute name.
 127    *
 128    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
 129    * resource.
 130    * @param[in] attrib A <code>PP_MediaStreamVideoTrack_Attrib</code> for
 131    * querying.
 132    * @param[out] value A int32_t for storing the attribute value on success.
 133    * Otherwise, the value will not be changed.
 134    *
 135    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
 136    */
 137   int32_t GetAttrib([in] PP_Resource video_track,
 138                     [in] PP_MediaStreamVideoTrack_Attrib attrib,
 139                     [out] int32_t value);
 140
 141   /**
 142    * Returns the track ID of the underlying MediaStream video track.
 143    *
 144    * @param[in] video_track The <code>PP_Resource</code> to check.
 145    *
 146    * @return A <code>PP_Var</code> containing the MediaStream track ID as
 147    * a string.
 148    */
 149   PP_Var GetId([in] PP_Resource video_track);
 150
 151   /**
 152    * Checks whether the underlying MediaStream track has ended.
 153    * Calls to GetFrame while the track has ended are safe to make and will
 154    * complete, but will fail.
 155    *
 156    * @param[in] video_track The <code>PP_Resource</code> to check.
 157    *
 158    * @return A <code>PP_Bool</code> with <code>PP_TRUE</code> if the given
 159    * MediaStream track has ended or <code>PP_FALSE</code> otherwise.
 160    */
 161   [on_failure=PP_TRUE]
 162   PP_Bool HasEnded([in] PP_Resource video_track);
 163
 164   /**
 165    * Gets the next video frame from the MediaStream track.
 166    * If internal processing is slower than the incoming frame rate, new frames
 167    * will be dropped from the incoming stream. Once the input buffer is full,
 168    * frames will be dropped until <code>RecycleFrame()</code> is called to free
 169    * a spot for another frame to be buffered.
 170    * If there are no frames in the input buffer,
 171    * <code>PP_OK_COMPLETIONPENDING</code> will be returned immediately and the
 172    * <code>callback</code> will be called when a new frame is received or an
 173    * error happens.
 174    *
 175    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
 176    * resource.
 177    * @param[out] frame A <code>PP_Resource</code> corresponding to a VideoFrame
 178    * resource.
 179    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
 180    * completion of GetFrame().
 181    *
 182    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
 183    * Returns PP_ERROR_NOMEMORY if <code>max_buffered_frames</code> frames buffer
 184    * was not allocated successfully.
 185    */
 186   int32_t GetFrame([in] PP_Resource video_track,
 187                    [out] PP_Resource frame,
 188                    [in] PP_CompletionCallback callback);
 189
 190   /**
 191    * Recycles a frame returned by <code>GetFrame()</code>, so the track can
 192    * reuse the underlying buffer of this frame. And the frame will become
 193    * invalid. The caller should release all references it holds to
 194    * <code>frame</code> and not use it anymore.
 195    *
 196    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
 197    * resource.
 198    * @param[in] frame A <code>PP_Resource</code> corresponding to a VideoFrame
 199    * resource returned by <code>GetFrame()</code>.
 200    *
 201    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
 202    */
 203   int32_t RecycleFrame([in] PP_Resource video_track,
 204                        [in] PP_Resource frame);
 205
 206   /**
 207    * Closes the MediaStream video track and disconnects it from video source.
 208    * After calling <code>Close()</code>, no new frames will be received.
 209    *
 210    * @param[in] video_track A <code>PP_Resource</code> corresponding to a
 211    * MediaStream video track resource.
 212    */
 213   void Close([in] PP_Resource video_track);
 214 };
 215