[PPAPI] API definition for video media stream artifacts

ppapi/api/ppb_media_stream_video_track.idl

+/* Copyright (c) 2013 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/**
+ * Defines the <code>PPB_MediaStreamVideoTrack</code> interface. Used for
+ * receiving video frames from a MediaStream video track in the browser.
+ * This interface is still in development (Dev API status) and may change.
+ */
+label Chrome {
+  [channel=dev] M33 = 0.1

[yzshen1, 2013/12/20 23:37:43]

M34? :) Time flies.

[Peng, 2013/12/23 02:41:49]

Done.

+};
+
+/**
+ */
+interface PPB_MediaStreamVideoTrack {
+  /**
+   * Determines if a resource is a MediaStream video track resource.
+   *
+   * @param[in] resource The <code>PP_Resource</code> to test.
+   *
+   * @return A <code>PP_Bool</code> with <code>PP_TRUE</code> if the given
+   * resource is a Mediastream video track resource or <code>PP_FALSE</code>
+   * otherwise.
+   */
+  PP_Bool IsMediaStreamVideoTrack([in] PP_Resource resource);
+
+  /**
+   * Configures underlaying frame buffers for incoming frames.
+   * If the application doesn't want to drop frames, then the
+   * |frame_buffer_size| should be chosen such that inter-frame processing time
+   * variability won't overrun the  input buffer. If the buffer is overfilled,

[yzshen1, 2013/12/20 23:37:43]

nit: extra space before 'input'.

[Peng, 2013/12/23 02:41:49]

Done.

+   * then frames will be dropped. The application can detect this by examining
+   * the timestamp on returned frames. If |Configure()| is not used, default
+   * settings will be used.

[bbudge, 2013/12/20 23:58:13]

Could you make it clearer that this is the number of video frames in the buffer,
rather than the actual size in bytes?

[Peng, 2013/12/23 02:41:49]

Done.

+   *
+   * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
+   * resource.
+   * @param[in] frame_buffer_size The maximum number of video frames to hold in
+   * input buffer.
+   *
+   * @return An int32_t containing a result code from <code>pp_errors.h</code>.
+   */
+  int32_t Configure([in] PP_Resource video_track,
+                    [in] uint32_t frame_buffer_size);
+
+  /**
+   * Returns the track ID of the underlying MediaStream video track.
+   *
+   * @param[in] video_track The <code>PP_Resource</code> to check.
+   *
+   * @return A <code>PP_Var</code> containing the MediaStream track ID as
+   * a string.
+   */
+  PP_Var GetId([in] PP_Resource video_track);
+
+  /**
+   * Checks whether the underlying MediaStream track has ended.
+   * Calls to GetFrame while the track has ended are safe to make and will
+   * complete, but will fail.
+   *
+   * @param[in] video_track The <code>PP_Resource</code> to check.
+   *
+   * @return A <code>PP_Bool</code> with <code>PP_TRUE</code> if the given
+   * MediaStream track has ended or <code>PP_FALSE</code> otherwise.
+   */
+  PP_Bool HasEnded([in] PP_Resource video_track);
+
+  /**
+   * Gets the next video frame from the MediaStream track.
+   * If internal processing is slower than the incoming frame rate, new frames
+   * will be dropped from the incoming stream. Once the input buffer is full,
+   * frames will be dropped until |ReuseFrame()| is called to free a spot for
+   * another frame to be buffered. If the caller holds a frame got from previous

[yzshen1, 2013/12/20 23:37:43]

*the* previous call

[Peng, 2013/12/23 02:41:49]

Done.

+   * call of |GetFrame()|, an error will be returned. The caller should recycle

[yzshen1, 2013/12/20 23:37:43]

what error will be returned in this case?

[Peng, 2013/12/23 02:41:49]

Done.

+   * previous frame, before getting next frame.

[yzshen1, 2013/12/20 23:37:43]

*the* previous frame. *the* next frame.

[Peng, 2013/12/23 02:41:49]

Done.

+   *
+   * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
+   * resource.
+   * @param[out] frame A <code>PP_Resource</code> corresponding to a VideoFrame
+   * resource.
+   * @param[in] callback A <code>PP_CompletionCallback</code> to be called upon
+   * completion of GetFrame().
+   *
+   * @return An int32_t containing a result code from <code>pp_errors.h</code>.
+   * Returns PP_ERROR_NOMEMORY if |frame_buffer_size| frames buffer was not
+   * allocated successfully.
+   */
+  int32_t GetFrame([in] PP_Resource video_track,
+                   [out] PP_Resource frame,
+                   [in] PP_CompletionCallback callback);
+
+  /**
+   * Recycles a frame got from |GetFrame()|, so the track can reuse

[bbudge, 2013/12/20 23:58:13]

s/got/gotten but really 'returned by' might be less awkward in this situation.

[Peng, 2013/12/23 02:41:49]

Done.

+   * the underlaying buffer of this frame. And the frame will become invalidate.

[yzshen1, 2013/12/20 23:37:43]

invalidate -> invalid

[Peng, 2013/12/23 02:41:49]

Done.

+   * The caller should release all references it holds to |frame|, and not use
+   * it anymore.
+   *
+   * @param[in] video_track A <code>PP_Resource</code> corresponding to a video
+   * resource.
+   * @param[in] video_frame A <code>PP_Resource</code> corresponding to a

[yzshen1, 2013/12/20 23:37:43]

the parameter name is |frame|.

[Peng, 2013/12/23 02:41:49]

Done.

+   * VideoFrame resource got from |GetFrame()|
+   *
+   * @return An int32_t containing a result code from <code>pp_errors.h</code>.
+   * Retruns PP_ERROR_BADARGUMENT if frame isn't a vaild video frame got from

[bbudge, 2013/12/20 23:58:13]

see comment above.

[Peng, 2013/12/23 02:41:49]

Done.

+   * |GetFrame()|.
+   */
+  int32_t ReuseFrame([in] PP_Resource video_track,
+                     [in] PP_Resource frame);
+
+  /**
+   * Closes the MediaStream video track, and disconnects it from video source.
+   * And then not new frames will be recevied. After calling |Close()|, the

[yzshen1, 2013/12/20 23:37:43]

not -> no.

[Peng, 2013/12/23 02:41:49]

Done.

+   * video track should not be used anymore.

[bbudge, 2013/12/20 23:58:13]

How about this?

* Closes the MediaStream video track, and disconnects it from video source.
* After calling Close, no new frames will be received.

[Peng, 2013/12/23 02:41:49]

Done.

+   *
+   * @param[in] video_track A <code>PP_Resource</code> corresponding to a
+   * MediaStream video track resource.
+   */
+  void Close([in] PP_Resource video_track);
+};
+