Implement flushing in VTVideoDecodeAccelerator.

content/common/gpu/media/vt_video_decode_accelerator.h

 // Copyright 2014 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.
 
 #ifndef CONTENT_COMMON_GPU_MEDIA_VT_VIDEO_DECODE_ACCELERATOR_H_
 #define CONTENT_COMMON_GPU_MEDIA_VT_VIDEO_DECODE_ACCELERATOR_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 46 matching lines @@
 
  private:
   struct DecodedFrame {
     DecodedFrame(int32_t bitstream_id, CVImageBufferRef image_buffer);
     ~DecodedFrame();
 
     int32_t bitstream_id;
     base::ScopedCFTypeRef<CVImageBufferRef> image_buffer;
   };
 
+  // Actions are the possible types of pending operations, which are queued
+  // by Flush(), Reset(), and Destroy().
+  enum Action {
+    ACTION_FLUSH,
+    ACTION_RESET,
+    ACTION_DESTROY
+  };
+
+  // PendingActions contain the |bitstream_id| of a frame that, once decoded and
+  // sent, a particular |action| should be completed at.
+  struct PendingAction {
+    PendingAction(Action action, int32_t bitstream_id);
+    ~PendingAction();
+
+    Action action;
+    int32_t bitstream_id;
+  };
+
   // Methods for interacting with VideoToolbox. Run on |decoder_thread_|.
   void ConfigureDecoder(
       const std::vector<const uint8_t*>& nalu_data_ptrs,
       const std::vector<size_t>& nalu_data_sizes);
   void DecodeTask(const media::BitstreamBuffer);
+  void FlushTask();
 
   // Methods for interacting with |client_|. Run on |gpu_task_runner_|.
   void OutputTask(DecodedFrame frame);
   void SizeChangedTask(gfx::Size coded_size);
-  void SendPictures();
+
+  // Send decoded frames up to and including |up_to_bitstream_id|, and return
+  // the last sent |bitstream_id|.
+  int32_t SendPictures(int32_t up_to_bitstream_id);
+
+  // Since VideoToolbox has no reset feature (only flush), and the VDA API
+  // allows Decode() and Flush() calls during a reset operation, it's possible
+  // to have multiple pending actions at once. We handle the fully general case
+  // of an arbitrary sequence of pending actions (in reality, there should
+  // probably be at most one reset and one flush at a time).
+  void QueueAction(Action action);
+
+  // Process queued decoded frames, usually by sending them (unless there
+  // is a pending ACTION_RESET or ACTION_DESTROY, in which case they are
+  // dropped), completing queued actions along the way.
+  void ProcessDecodedFrames();
+
+  // Complete a particular action, by eg. calling NotifyFlushDone().
+  // Warning: Deletes |this| if |action| is ACTION_DESTROY.
+  void CompleteAction(Action action);
+
+  // Complete all actions pending for a particular |bitstream_id|.
+  // Warning: Do not call if there is a pending ACTION_DESTROY.
+  void CompleteActions(int32_t bitstream_id);
 
   //
   // GPU thread state.
   //
   CGLContextObj cgl_context_;
   media::VideoDecodeAccelerator::Client* client_;
   gfx::Size texture_size_;
+  std::queue<PendingAction> pending_actions_;
+  std::queue<int32_t> pending_bitstream_ids_;
 
   // Texture IDs of pictures.
   // TODO(sandersd): A single map of structs holding picture data.
   std::map<int32_t, uint32_t> texture_ids_;
 
   // Pictures ready to be rendered to.
   std::queue<int32_t> available_picture_ids_;
 
   // Decoded frames ready to render.
   std::queue<DecodedFrame> decoded_frames_;
 
   // Image buffers kept alive while they are bound to pictures.
   std::map<int32_t, base::ScopedCFTypeRef<CVImageBufferRef>> picture_bindings_;
 
   //
   // Decoder thread state.
   //
   VTDecompressionOutputCallbackRecord callback_;
   base::ScopedCFTypeRef<CMFormatDescriptionRef> format_;
   base::ScopedCFTypeRef<VTDecompressionSessionRef> session_;
   media::H264Parser parser_;
   gfx::Size coded_size_;
 
   //
-  // Unprotected shared state (set up and torn down on GPU thread).
+  // Shared state (set up and torn down on GPU thread).
   //
   scoped_refptr<base::SingleThreadTaskRunner> gpu_task_runner_;
 
   // This WeakPtrFactory does not need to be last as its pointers are bound to
   // the same thread it is destructed on (the GPU thread).
   base::WeakPtrFactory<VTVideoDecodeAccelerator> weak_this_factory_;
 
   // Declared last to ensure that all decoder thread tasks complete before any
   // state is destructed.
   base::Thread decoder_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(VTVideoDecodeAccelerator);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_GPU_MEDIA_VT_VIDEO_DECODE_ACCELERATOR_H_