The guts of the video renderer logic that relate to timing and queuing of fra...

chrome/renderer/media/video_renderer_impl.h

 // Copyright (c) 2009 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.
 //
 // The video renderer implementation to be use by the media pipeline. It lives
 // inside video renderer thread and also WebKit's main thread. We need to be
 // extra careful about members shared by two different threads, especially
 // video frame buffers.
 //
 // Methods called from WebKit's main thread:
 //   Paint()
 //   SetRect()
 
 #ifndef CHROME_RENDERER_MEDIA_VIDEO_RENDERER_IMPL_H_
 #define CHROME_RENDERER_MEDIA_VIDEO_RENDERER_IMPL_H_
 
-#include <deque>
-
-#include "base/lock.h"
-#include "base/task.h"
 #include "base/gfx/platform_canvas.h"
+#include "base/gfx/rect.h"
+#include "base/gfx/size.h"
 #include "chrome/renderer/webmediaplayer_delegate_impl.h"
-#include "base/gfx/rect.h"
+#include "media/base/buffers.h"
 #include "media/base/factory.h"
 #include "media/base/filters.h"
+#include "media/filters/video_renderer_base.h"
 #include "webkit/glue/webmediaplayer_delegate.h"
 
-class SubmitReadsTask;
+class VideoRendererImpl : public media::VideoRendererBase {
+ public:
+  // Methods for painting called by the WebMediaPlayerDelegateImpl
 
-class VideoRendererImpl : public media::VideoRenderer {
- public:
-  // media::MediaFilter implementation.
-  virtual void Stop();
+  // This method is called with the same rect as the Paint method and could
+  // be used by future implementations to implement an improved color space +
+  // scale code on a seperate thread.  Since we always do the streach on the
+  // same thread as the Paint method, we just ignore the call for now.
+  virtual void SetRect(const gfx::Rect& rect) {}
 
-  // media::VideoRenderer implementation.
-  virtual bool Initialize(media::VideoDecoder* decoder);
-
-  // Methods for painting called by the WebMediaPlayerDelegateImpl
-  // TODO(ralphl): What the *$*%##@ is this?  What does it mean?  How do we
-  // treat the "rect"?  Is is clipping?
-  virtual void SetRect(const gfx::Rect& rect);
-
-  // TODO(ralphl): What is this rect?  Is it relative to the canvas?
-  virtual void Paint(skia::PlatformCanvas* canvas, const gfx::Rect& rect);
+  // Paint the current front frame on the |canvas| streaching it to fit the
+  // |dest_rect|
+  virtual void Paint(skia::PlatformCanvas* canvas, const gfx::Rect& dest_rect);
 
   // Static method for creating factory for this object.
   static media::FilterFactory* CreateFactory(
       WebMediaPlayerDelegateImpl* delegate) {
     return new media::FilterFactoryImpl1<
         VideoRendererImpl, WebMediaPlayerDelegateImpl*>(delegate);
   }
 
-  // Implementation of AssignableBuffer<this>::OnAssignment method.
-  void OnAssignment(media::VideoFrame* video_frame);
+ private:
+  // Method called by base class during initialization.
+  virtual bool OnInitialize(size_t width, size_t height);
 
- private:
-  friend class SubmitReadsTask;
+  // Method called by the VideoRendererBase when a repaint is needed.
+  virtual void OnPaintNeeded();
+
   friend class media::FilterFactoryImpl1<VideoRendererImpl,
                                          WebMediaPlayerDelegateImpl*>;
 
   // Constructor and destructor are private.  Only the filter factory is
   // allowed to create instances.
   explicit VideoRendererImpl(WebMediaPlayerDelegateImpl* delegate);
-  virtual ~VideoRendererImpl();
-
-  // Answers question from the factory to see if we accept |format|.
-  static bool IsMediaFormatSupported(const media::MediaFormat* format);
-
-  // Used by the IsMediaFormatSupported and Initialize methods.  Examines the
-  // |media_format| and returns true if the format is supported.  Both output
-  // parameters, |width_out| and |height_out| are required and must not be NULL.
-  static bool ParseMediaFormat(const media::MediaFormat* media_format,
-                               int* width_out,
-                               int* height_out);
-
-  // Used internally to post a task that will call the SubmitReads() method.
-  // The |lock_| must be acquired before calling this method.  If the value of
-  // |number_of_reads_needed_| is 0 or if there is already a pending task then
-  // this method simply returns and does not post a new task.
-  void PostSubmitReadsTask();
-
-  // Examines the |number_of_reads_needed_| member and calls the decoder to
-  // read the necessary number of frames.
-  void SubmitReads();
-
-  // For simplicity, we use the |delegate_| member to indicate if we have been
-  // stopped or not.
-  bool IsRunning() const { return (delegate_ != NULL); }
-
-  // Throw away all frames in the queue.  The |lock_| must have been acquired
-  // before calling this method.
-  void DiscardAllFrames();
-
-  // This method is always called with the object's |lock_| acquired..
-  // The bool return value indicates weather or not the front of the queue has
-  // been updated.  If this method returns true, then the front of the queue
-  // is a new video frame, otherwise, the front is the same as the last call.
-  // Given the current |time|, this method updates the state of the video frame
-  // queue.  The caller may pass in a |new_frame| which will be added to the
-  // queue in the appropriate position based on the frame's timestamp.  The
-  // |front_frame_out| and |time_next_frame_out| parameters are both optional
-  // and can be NULL.  If |front_frame_out| is non-NULL, then it is returned as
-  // either NULL, which indicates that there are no frames in the queue, or
-  // it will be a pointer to the frame at the front of the queue.  NOTE:  THIS
-  // FRAME'S REFERENCE COUNT HAS BEEN INCREMENTED BY THIS CALL.  THE
-  // CALLING FUNCTION MUST CALL |front_frame_out|->Release();
-  // If the |time_next_frame_out| parameter is non-NULL then it will be assigned
-  // the stream time of the next frame in the queue.  This is used by the Paint
-  // method to schedule a time update callback at the appropriate presentation
-  // time for the next frame.
-  bool UpdateQueue(base::TimeDelta time,
-                   media::VideoFrame* new_frame,
-                   media::VideoFrame** front_frame_out,
-                   base::TimeDelta* time_next_frame_out);
+  virtual ~VideoRendererImpl() {}
 
   // Internal method used by the Paint method to convert the specified video
   // frame to RGB, placing the converted pixels in the |current_frame_| bitmap.
   void CopyToCurrentFrame(media::VideoFrame* video_frame);
 
-  // Called when the clock is updated by the audio renderer of when a scheduled
-  // callback is called based on the interpolated current position of the media
-  // stream.
-  void TimeUpdateCallback(base::TimeDelta time);
-
-  // Critical section.  There is only one for this object.  Used to serialize
-  // access to the following members:
-  //  |queue_| for obvious reasons
-  //  |delegate_| because it is used by methods that can be called from random
-  //      threads to determine if the render has been stopped (it will
-  //      be NULL if stopped)
-  //  |submit_reads_task_| to prevent multiple scheduling of the task and to
-  //      allow for safe cancelation of the task.
-  //  |current_frame_timestamp_| because member is used by the render
-  //      thread in the Paint method and by DiscardAllFrames which can be
-  //      called on the decoder's thread when a seek occurs.
-  //  |number_of_reads_needed_| is modified by UpdateQueue from the decoder
-  //      thread, the renderer thread, and the pipeline thread.
-  //  |preroll_complete_| has a very small potential race condition if the
-  //      OnAssignment method were reentered for the last frame in the queue
-  //      and an end-of-stream frame.
-  Lock lock_;
-
   // Pointer to our parent object that is called to request repaints.
   WebMediaPlayerDelegateImpl* delegate_;
 
-  // Pointer to the decoder that will feed us with video frames.
-  scoped_refptr<media::VideoDecoder> decoder_;
+  // An RGB bitmap used to convert the video frames.
+  SkBitmap bitmap_;
 
-  // If non-NULL then a task has been scheduled to submit read requests to the
-  // video decoder.
-  CancelableTask* submit_reads_task_;
+  // These two members are used to determine if the |bitmap_| contains
+  // an already converted image of the current frame.  IMPORTANT NOTE:  The
+  // value of |last_converted_frame_| must only be used for comparison purposes,
+  // and it should be assumed that the value of the pointer is INVALID unless
+  // it matches the pointer returned from GetCurrentFrame().  Even then, just
+  // to make sure, we compare the timestamp to be sure the bits in the
+  // |current_frame_bitmap_| are valid.
+  media::VideoFrame* last_converted_frame_;
+  base::TimeDelta last_converted_timestamp_;
 
-  // The number of buffers we need to request.  This member is updated by any
-  // method that removes frames from the queue, such as UpdateQueue and
-  // DiscardAllFrames.
-  int number_of_reads_needed_;
-
-  // An RGB bitmap of the current frame.  Note that we use the timestamp to
-  // determine if the frame contents need to be color space converted, or if the
-  // |current_frame_| member contains the correct image for the queue front.
-  SkBitmap current_frame_;
-  base::TimeDelta current_frame_timestamp_;
-
-  // TODO(ralphl):  Try to understand all of the various "rect" and dimension
-  // aspects of the renderer and document it so that other people can understand
-  // it too.  I can not accurately describe what the role of this member is now.
-  gfx::Rect rect_;
-
-  // The queue of video frames.  The front of the queue is the frame that should
-  // be displayed.
-  typedef std::deque<media::VideoFrame*> VideoFrameQueue;
-  VideoFrameQueue queue_;
-
-  // True if we have received a full queue of video frames from the decoder.
-  // We don't call FilterHost::InitializationComplete() until the the queue
-  // is full.
-  bool preroll_complete_;
+  // The size of the video.
+  gfx::Size video_size_;
 
   DISALLOW_COPY_AND_ASSIGN(VideoRendererImpl);
 };
 
 #endif  // CHROME_RENDERER_MEDIA_VIDEO_RENDERER_IMPL_H_