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   [channel=dev] M36 = 1.0
  17 };
  18
  19 /**
  20  * This enumeration contains video track attributes which are used by
  21  * <code>Configure()</code>.
  22  */
  23 enum PP_MediaStreamVideoTrack_Attrib {
  24   /**
  25    * Attribute list terminator.
  26    */
  27   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE = 0,
  28
  29   /**
  30    * The maximum number of frames to hold in the input buffer.
  31    * Note: this is only used as advisory; the browser may allocate more or fewer
  32    * based on available resources. How many frames to buffer depends on usage -
  33    * request at least 2 to make sure latency doesn't cause lost frames. If
  34    * the plugin expects to hold on to more than one frame at a time (e.g. to do
  35    * multi-frame processing), it should request that many more.
  36    * If this attribute is not specified or value 0 is specified for this
  37    * attribute, the default value will be used.
  38    */
  39   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES = 1,
  40
  41   /**
  42    * The width of video frames in pixels. It should be a multiple of 4.
  43    * If the specified size is different from the video source (webcam),
  44    * frames will be scaled to specified size.
  45    * If this attribute is not specified or value 0 is specified, the original
  46    * frame size of the video track will be used.
  47    *
  48    * Maximum value: 4096 (4K resolution).
  49    */
  50   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_WIDTH = 2,
  51
  52   /**
  53    * The height of video frames in pixels. It should be a multiple of 4.
  54    * If the specified size is different from the video source (webcam),
  55    * frames will be scaled to specified size.
  56    * If this attribute is not specified or value 0 is specified, the original
  57    * frame size of the video track will be used.
  58    *
  59    * Maximum value: 4096 (4K resolution).
  60    */
  61   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_HEIGHT = 3,
  62
  63   /**
  64    * The format of video frames. The attribute value is
  65    * a <code>PP_VideoFrame_Format</code>. If the specified format is different
  66    * from the video source (webcam), frames will be converted to specified
  67    * format.
  68    * If this attribute is not specified or value
  69    * <code>PP_VIDEOFRAME_FORMAT_UNKNOWN</code> is specified, the orignal frame
  70    * format of the video track will be used.
  71    */
  72   PP_MEDIASTREAMVIDEOTRACK_ATTRIB_FORMAT = 4
  73 };
  74
  75 [version=0.1]
  76 interface PPB_MediaStreamVideoTrack {
  77   /**
  78    * Creates a PPB_MediaStreamVideoTrack resource for video output. Call this
  79    * when you will be creating frames and putting them to the track.
  80    *
  81    * @param[in] instance A <code>PP_Instance</code> identifying one instance of
  82    * a module.
  83    *
  84    * @return A <code>PP_Resource</code> corresponding to a
  85    * PPB_MediaStreamVideoTrack resource if successful, 0 if failed.
  86    */
  87   [version=1.0]
  88   PP_Resource Create([in] PP_Instance instance);
  89
  90   /**
  91    * Determines if a resource is a MediaStream video track resource.
  92    *
  93    * @param[in] resource The <code>PP_Resource</code> to test.
  94    *
  95    * @return A <code>PP_Bool</code> with <code>PP_TRUE</code> if the given
  96    * resource is a Mediastream video track resource or <code>PP_FALSE</code>
  97    * otherwise.
  98    */
  99   PP_Bool IsMediaStreamVideoTrack([in] PP_Resource resource);
 100
 101   /**
 102    * Configures underlying frame buffers for incoming frames.
 103    * If the application doesn't want to drop frames, then the
 104    * <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES</code> should be
 105    * chosen such that inter-frame processing time variability won't overrun the
 106    * input buffer. If the buffer is overfilled, then frames will be dropped.
 107    * The application can detect this by examining the timestamp on returned
 108    * frames. If some attributes are not specified, default values will be used
 109    * for those unspecified attributes. If <code>Configure()</code> is not
 110    * called, default settings will be used.
 111    * Example usage from plugin code:
 112    * @code
 113    * int32_t attribs[] = {
 114    *     PP_MEDIASTREAMVIDEOTRACK_ATTRIB_BUFFERED_FRAMES, 4,
 115    *     PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE};
 116    * track_if->Configure(track, attribs, callback);
 117    * @endcode
 118    *
 119    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
 120    * resource.
 121    * @param[in] attrib_list A list of attribute name-value pairs in which each
 122    * attribute is immediately followed by the corresponding desired value.
 123    * The list is terminated by
 124    * <code>PP_MEDIASTREAMVIDEOTRACK_ATTRIB_NONE</code>.
 125    * @param[in] callback <code>PP_CompletionCallback</code> to be called upon
 126    * completion of <code>Configure()</code>.
 127    *
 128    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
 129    * Returns <code>PP_ERROR_INPROGRESS</code> if there is a pending call of
 130    * <code>Configure()</code> or <code>GetFrame()</code>, or the plugin
 131    * holds some frames which are not recycled with <code>RecycleFrame()</code>.
 132    * If an error is returned, all attributes and the underlying buffer will not
 133    * be changed.
 134    */
 135   int32_t Configure([in] PP_Resource video_track,
 136                     [in] int32_t[] attrib_list,
 137                     [in] PP_CompletionCallback callback);
 138
 139   /**
 140    * Gets attribute value for a given attribute name.
 141    *
 142    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
 143    * resource.
 144    * @param[in] attrib A <code>PP_MediaStreamVideoTrack_Attrib</code> for
 145    * querying.
 146    * @param[out] value A int32_t for storing the attribute value on success.
 147    * Otherwise, the value will not be changed.
 148    *
 149    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
 150    */
 151   int32_t GetAttrib([in] PP_Resource video_track,
 152                     [in] PP_MediaStreamVideoTrack_Attrib attrib,
 153                     [out] int32_t value);
 154
 155   /**
 156    * Returns the track ID of the underlying MediaStream video track.
 157    *
 158    * @param[in] video_track The <code>PP_Resource</code> to check.
 159    *
 160    * @return A <code>PP_Var</code> containing the MediaStream track ID as
 161    * a string.
 162    */
 163   PP_Var GetId([in] PP_Resource video_track);
 164
 165   /**
 166    * Checks whether the underlying MediaStream track has ended.
 167    * Calls to GetFrame while the track has ended are safe to make and will
 168    * complete, but will fail.
 169    *
 170    * @param[in] video_track The <code>PP_Resource</code> to check.
 171    *
 172    * @return A <code>PP_Bool</code> with <code>PP_TRUE</code> if the given
 173    * MediaStream track has ended or <code>PP_FALSE</code> otherwise.
 174    */
 175   [on_failure=PP_TRUE]
 176   PP_Bool HasEnded([in] PP_Resource video_track);
 177
 178   /**
 179    * Gets the next video frame from the MediaStream track.
 180    * If internal processing is slower than the incoming frame rate, new frames
 181    * will be dropped from the incoming stream. Once the input buffer is full,
 182    * frames will be dropped until <code>RecycleFrame()</code> is called to free
 183    * a spot for another frame to be buffered.
 184    * If there are no frames in the input buffer,
 185    * <code>PP_OK_COMPLETIONPENDING</code> will be returned immediately and the
 186    * <code>callback</code> will be called when a new frame is received or an
 187    * error happens.
 188    *
 189    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
 190    * resource.
 191    * @param[out] frame A <code>PP_Resource</code> corresponding to a VideoFrame
 192    * resource.
 193    * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
 194    * completion of GetFrame().
 195    *
 196    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
 197    * Returns PP_ERROR_NOMEMORY if <code>max_buffered_frames</code> frames buffer
 198    * was not allocated successfully.
 199    */
 200   int32_t GetFrame([in] PP_Resource video_track,
 201                    [out] PP_Resource frame,
 202                    [in] PP_CompletionCallback callback);
 203
 204   /**
 205    * Recycles a frame returned by <code>GetFrame()</code>, so the track can
 206    * reuse the underlying buffer of this frame. And the frame will become
 207    * invalid. The caller should release all references it holds to
 208    * <code>frame</code> and not use it anymore.
 209    *
 210    * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
 211    * resource.
 212    * @param[in] frame A <code>PP_Resource</code> corresponding to a VideoFrame
 213    * resource returned by <code>GetFrame()</code>.
 214    *
 215    * @return An int32_t containing a result code from <code>pp_errors.h</code>.
 216    */
 217   int32_t RecycleFrame([in] PP_Resource video_track,
 218                        [in] PP_Resource frame);
 219
 220   /**
 221    * Closes the MediaStream video track and disconnects it from video source.
 222    * After calling <code>Close()</code>, no new frames will be received.
 223    *
 224    * @param[in] video_track A <code>PP_Resource</code> corresponding to a
 225    * MediaStream video track resource.
 226    */
 227   void Close([in] PP_Resource video_track);
 228
 229   /**
 230    * Gets a free frame for output. The frame is allocated by
 231    * <code>Configure()</code>. The caller should fill it with frame data, and
 232    * then use |PutFrame()| to send the frame back.
 233    */
 234   [version=1.0]
 235   int32_t GetEmptyFrame([in] PP_Resource video_track,
 236                         [out] PP_Resource frame,
 237                         [in] PP_CompletionCallback callback);
 238
 239   /**
 240    * Sends a frame returned by |GetEmptyFrame()| to the output track.
 241    * After this function, the |frame| should not be used anymore and the
 242    * caller should release the reference that it holds.
 243    */
 244   [version=1.0]
 245   int32_t PutFrame([in] PP_Resource video_track, [in] PP_Resource frame);
 246 };
 247