MJPEG acceleration for video capture using VAAPI

content/common/gpu/media/vaapi_jpeg_decode_accelerator.h

+// Copyright 2015 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.
+//
+// This file contains an implementation of VideoDecoderAccelerator
+// that utilizes hardware video decoder present on Intel CPUs.
+
+#ifndef CONTENT_COMMON_GPU_MEDIA_VAAPI_JPEG_DECODE_ACCELERATOR_H_
+#define CONTENT_COMMON_GPU_MEDIA_VAAPI_JPEG_DECODE_ACCELERATOR_H_
+
+#include <map>
+#include <queue>
+#include <utility>
+#include <vector>
+
+#include "base/logging.h"
+#include "base/memory/linked_ptr.h"
+#include "base/memory/shared_memory.h"
+#include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop.h"
+#include "base/synchronization/condition_variable.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/non_thread_safe.h"
+#include "base/threading/thread.h"
+#include "content/common/content_export.h"
+#include "content/common/gpu/media/vaapi_jpeg_decoder.h"
+#include "content/common/gpu/media/vaapi_wrapper.h"
+#include "media/base/bitstream_buffer.h"
+#include "media/video/jpeg_decode_accelerator.h"
+#include "media/video/picture.h"
+
+namespace content {
+
+// Class to provide JPEG decode acceleration for Intel systems with hardware
+// support for it, and on which libva is available.
+// Decoding tasks are performed in a separate decoding thread.
+//
+// Threading/life-cycle: this object is created & destroyed on the GPU
+// ChildThread.  A few methods on it are called on the decoder thread which is
+// stopped during |this->Destroy()|, so any tasks posted to the decoder thread
+// can assume |*this| is still alive.  See |weak_this_| below for more details.
+class CONTENT_EXPORT VaapiJpegDecodeAccelerator
+    : public media::JpegDecodeAccelerator {
+ public:
+  VaapiJpegDecodeAccelerator();
+  ~VaapiJpegDecodeAccelerator() override;
+
+  // media::JpegDecodeAccelerator implementation.
+  bool Initialize(media::JpegDecodeAccelerator::Client* client) override;
+  void Decode(const media::BitstreamBuffer& bitstream_buffer,
+              const scoped_refptr<media::VideoFrame>& video_frame) override;
+  void Destroy() override;
+
+ private:
+  // Notify the client that an error has occurred and decoding cannot continue.
+  void NotifyError(int32_t bitstream_buffer_id, Error error);
+
+  // Map the received input buffer into this process' address space and
+  // queue it for decode.
+  void MapAndQueueNewInputBuffer(
+      const media::BitstreamBuffer& bitstream_buffer,
+      const scoped_refptr<media::VideoFrame>& video_frame);
+
+  // Continue decoding given input buffers and sleep waiting for input/output

[wuchengli, 2015/04/15 07:11:59]

There is no sleep waiting.

[kcwu, 2015/04/16 14:38:29]

Done.

+  // as needed. Will exit if a new set of surfaces or reset/flush/destroy

[wuchengli, 2015/04/15 07:11:59]

Update the comment.

[kcwu, 2015/04/16 14:38:28]

Done.

+  // is requested.
+  void DecodeTask();
+
+  // Helper for Destroy(), doing all the actual work except for deleting self.
+  void Cleanup();
+
+  // TODO(kcwu) fix comment

[wuchengli, 2015/04/15 07:11:59]

Remove TODO and update the comment.

[kcwu, 2015/04/16 14:38:29]

Done.

+  // Callback to be executed once we have a |va_surface| to be output and
+  // an available |tfp_picture| to use for output.
+  // Puts contents of |va_surface| into given |tfp_picture|, releases the
+  // surface and passes the resulting picture to client for output.
+  bool OutputPicture(VASurfaceID va_surface_id,
+                     int32_t input_id,
+                     const scoped_refptr<media::VideoFrame>& video_frame);
+
+  // VAVDA state.
+  enum State {
+    // Initialize() not called yet or failed.
+    kUninitialized,
+    // DecodeTask running.
+    kDecoding,
+    // Idle, decoder in state ready to start/resume decoding.
+    kIdle,
+    // Destroying, waiting for the decoder to finish current task.
+    kDestroying,
+  };
+
+  // Protects input buffer and surface queues and state_.

[wuchengli, 2015/04/15 07:11:59]

Please list all the exact variable names instead of description. For example,
which surface queues? s/input buffer/input_buffers_|. s/state_/|state_|/

[kcwu, 2015/04/20 17:47:59]

Done.

+  base::Lock lock_;
+  State state_;
+
+  // An input buffer awaiting consumption, provided by the client.
+  struct InputBuffer {
+    InputBuffer();
+    ~InputBuffer();
+
+    int32 id;
+    size_t size;
+    scoped_ptr<base::SharedMemory> shm;
+

[wuchengli, 2015/04/15 07:11:59]

remove blank line

[kcwu, 2015/04/16 14:38:29]

Done.

+    scoped_refptr<media::VideoFrame> video_frame;
+  };
+
+  // Queue for incoming input buffers.
+  typedef std::queue<linked_ptr<InputBuffer>> InputBuffers;
+  InputBuffers input_buffers_;
+  // Signalled when input buffers are queued onto the input_buffers_ queue.

[wuchengli, 2015/04/15 07:11:59]

s/input_buffers_/|input_buffers_|/. Same for others in this file.

[kcwu, 2015/04/16 14:38:28]

Done.

+  base::ConditionVariable input_ready_;

[wuchengli, 2015/04/15 07:11:59]

not used. remove

[kcwu, 2015/04/16 14:38:29]

Done.

+
+  // Current input buffer at decoder.
+  linked_ptr<InputBuffer> curr_input_buffer_;
+
+  // ChildThread's message loop
+  base::MessageLoop* message_loop_;
+
+  // To expose client callbacks from VideoDecodeAccelerator.

[wuchengli, 2015/04/15 07:11:59]

s/VideoDecodeAccelerator/JpegDecodeAccelerator/

[kcwu, 2015/04/16 14:38:29]

Done.

+  // NOTE: all calls to these objects *MUST* be executed on message_loop_.
+  scoped_ptr<base::WeakPtrFactory<Client>> client_ptr_factory_;
+  base::WeakPtr<Client> client_;
+
+  // WeakPtr<> pointing to |this| for use in posting tasks from the decoder
+  // thread back to the ChildThread.  Because the decoder thread is a member of
+  // this class, any task running on the decoder thread is guaranteed that this
+  // object is still alive.  As a result, tasks posted from ChildThread to
+  // decoder thread should use base::Unretained(this), and tasks posted from the
+  // decoder thread to the ChildThread should use |weak_this_|.
+  base::WeakPtr<VaapiJpegDecodeAccelerator> weak_this_;
+
+  // Callback used when creating VASurface objects.
+  VASurface::ReleaseCB va_surface_release_cb_;

[wuchengli, 2015/04/15 07:11:59]

not used

[kcwu, 2015/04/16 14:38:29]

Done.

+
+  scoped_ptr<VaapiWrapper> vaapi_wrapper_;
+
+  // Comes after vaapi_wrapper_ to ensure its destructor is executed before
+  // vaapi_wrapper_ is destroyed.
+  scoped_ptr<VaapiJpegDecoder> decoder_;
+  base::Thread decoder_thread_;
+  // Use this to post tasks to |decoder_thread_| instead of
+  // |decoder_thread_.message_loop()| because the latter will be NULL once
+  // |decoder_thread_.Stop()| returns.
+  scoped_refptr<base::MessageLoopProxy> decoder_thread_proxy_;
+
+  // The WeakPtrFactory for |weak_this_|.
+  base::WeakPtrFactory<VaapiJpegDecodeAccelerator> weak_this_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(VaapiJpegDecodeAccelerator);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_COMMON_GPU_MEDIA_VAAPI_JPEG_DECODE_ACCELERATOR_H_