MJPEG acceleration for video capture using VAAPI

content/browser/renderer_host/gpu_jpeg_decoder.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.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_GPU_JPEG_DECODER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_GPU_JPEG_DECODER_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/message_loop/message_loop.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/thread.h"
+#include "content/common/content_export.h"
+#include "media/video/capture/video_capture_device.h"
+#include "media/video/jpeg_decode_accelerator.h"
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace media {
+class VideoFrame;
+}
+
+namespace content {
+
+// Adapter to GpuJpegDecodeAccelerator for VideoCaptureDevice::Client. It takes
+// care of GpuJpegDecodeAccelerator creation, shared memory, and threading
+// issues.
+//
+// All public methods, if not specified, are called on the same thread.

[wuchengli, 2015/05/13 15:04:06]

s/are/should/.

All public methods except JpegDecodeAccelerator::Client ones should be called
on the same thread. They are trampolined to an internal JPEG thread.
JpegDecodeAccelerator::Client methods also run on the JPEG thread.

[kcwu, 2015/05/25 18:20:34]

Done.

+class CONTENT_EXPORT GpuJpegDecoder
+    : public media::JpegDecodeAccelerator::Client,
+      public base::NonThreadSafe {
+ public:
+  typedef base::Callback<void(
+      scoped_ptr<media::VideoCaptureDevice::Client::Buffer>,
+      const scoped_refptr<media::VideoFrame>&,
+      const base::TimeTicks&)> DecodeDoneCB;
+  typedef base::Callback<void(const std::string&)> ErrorCB;
+
+  // Returns true if JPEG hardware decoding is supported on this device.
+  static bool Supported();
+
+  // |decode_done_cb| is called when decode succeed.
+  // |error_cb| is called when error.
+  GpuJpegDecoder(const DecodeDoneCB& decode_done_cb, const ErrorCB& error_cb);
+  ~GpuJpegDecoder();
+
+  // Creates and intializes decoder in GPU side. Returns falses if failed.
+  bool Initialize();
+
+  // Decodes a JPEG picture.
+  void DecodeCapturedData(
+      const uint8* data,
+      size_t in_buffer_size,
+      const media::VideoCaptureFormat& frame_format,
+      const base::TimeTicks& timestamp,
+      scoped_ptr<media::VideoCaptureDevice::Client::Buffer> out_buffer);
+
+  // JpegDecodeAccelerator::Client implementation.
+  // These will be called on jpeg thread.
+  virtual void VideoFrameReady(int32_t buffer_id) override;
+  virtual void NotifyError(int32_t buffer_id,
+                           media::JpegDecodeAccelerator::Error error) override;
+
+ private:
+  // Returns true if the decoding of last frame is not finished yet.
+  bool IsDecoding();
+
+  void CreateDecoderOnJpegThread();

[wuchengli, 2015/05/13 15:04:05]

s/CreateDecoderOnJpegThread/InitializeOnJpegThread/? CreateDecoderOnJpegThread
also initializes the decoder. It's more consistent with
DecodeCapturedDataOnJpegThread.

[kcwu, 2015/05/25 18:20:35]

Done.

+  void DecodeCapturedDataOnJpegThread(
+      const uint8* data,
+      size_t in_buffer_size,
+      const media::VideoCaptureFormat& frame_format,
+      const base::TimeTicks& timestamp,
+      scoped_ptr<media::VideoCaptureDevice::Client::Buffer> out_buffer);
+
+  base::Thread jpeg_thread_;
+  scoped_refptr<base::MessageLoopProxy> jpeg_thread_proxy_;
+  base::WaitableEvent create_event_;
+  base::WaitableEvent decode_event_;

[wuchengli, 2015/05/13 15:04:06]

|create_event_| is only used once. Let's combine these two.

[kcwu, 2015/05/25 18:20:34]

Done.

+
+  // The underlying JPEG decode accelerator.
+  scoped_ptr<media::JpegDecodeAccelerator> decoder_;
+
+  // The callback when decode succeed.

[wuchengli, 2015/05/13 15:04:05]

s/succeed/succeeds/. s/callback/callback to run/

[kcwu, 2015/05/25 18:20:35]

Done.

+  DecodeDoneCB decode_done_cb_;
+
+  // The callback when error.

[wuchengli, 2015/05/13 15:04:05]

s/callback/callback to run/. s/error/an error occurs/. 

[kcwu, 2015/05/25 18:20:35]

Done.

+  ErrorCB error_cb_;
+
+  // The closure of |decode_done_cb_| with bound parameters.
+  base::Closure decode_done_closure_;
+
+  // Next id for |in_buffer_|.
+  int32 next_bitstream_buffer_id_;
+
+  // Shared memory to store JPEG stream buffer. |in_buffer_| is backed by this.
+  scoped_ptr<base::SharedMemory> in_shared_memory_;
+
+  // JPEG stream buffer as input to JpegDecodeAccelerator.
+  media::BitstreamBuffer in_buffer_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuJpegDecoder);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_GPU_JPEG_DECODER_H_