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 "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.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 content {
+
+// Adapter to GpuJpegDecodeAccelerator for VideoCaptureDevice::Client. It takes
+// care of GpuJpegDecodeAccelerator creation, shared memory, and threading
+// issues. If decoding fails, it will fallback to software decode for current
+// frame and reject upcoming frames.
+//
+// There are two threads involved in this class. Ctor, dtor, Initialize(), and
+// DecodeCapturedData() are running on one thread (i.e., device thread for
+// Linux). The decoding responses (JpegDecodeAccelerator::Client functions) run
+// on IO thread.
+class CONTENT_EXPORT GpuJpegDecoder
+    : public media::JpegDecodeAccelerator::Client {
+ public:
+  // Return true if JPEG hardware decoding is supported on this device.
+  static bool Supported();
+
+  // |device_client| is where we request VideoCaptureDevice::Client::Buffer as
+  // output buffer from and send decoded result to.
+  GpuJpegDecoder(media::VideoCaptureDevice::Client* device_client);
+  ~GpuJpegDecoder();
+
+  // Create and intialize decoder in GPU side. Return false if failed.
+  bool Initialize();
+
+  // Return true if in failed state.
+  bool IsFailed();
+
+  // Decode a JPEG picture. If this class is in failed state,
+  // DecodeCapturedData() will ignore all decoding requests.
+  void DecodeCapturedData(const uint8* data,
+                          int length,
+                          const media::VideoCaptureFormat& frame_format,
+                          int rotation,
+                          const base::TimeTicks& timestamp);
+
+  // JpegDecodeAccelerator::Client implementation.
+  // These will be called on IO thread.
+  virtual void VideoFrameReady(int32_t buffer_id) override;
+  virtual void NotifyError(int32_t buffer_id,
+                           media::JpegDecodeAccelerator::Error error) override;
+
+ private:
+  // Fail state indicates to use software decode. See comment in
+  // FallbackToSoftwareDecode for detail.
+  enum FailState { NOT_FAIL, FAILING, FAILED };
+
+  // For keeping parameters of DecodeCapturedData. In case we need to pass them
+  // to software decoder if hardware decoding failed.
+  struct CapturedData {
+    // If accessed inside DecodeCapturedData(), |data| is owned by capturer
+    // (i.e., v4l2 driver on linux). Otherwise, |data| is backed by
+    // |in_shared_memory_|.
+    uint8* data;
+    int length;
+    media::VideoCaptureFormat frame_format;
+    int rotation;
+    base::TimeTicks timestamp;
+  };
+
+  bool IsDecoding();
+  // Check |bitstream_buffer_id| from GPU process is expected.
+  bool IsExpectedDecodeResponse(int32 bitstream_buffer_id);
+  // Current frame decoding is done. Allow DecodeCapturedData() to accept next
+  // frame.
+  void DecodeDone();
+  // Fallback current frame to software decode. Set flag to reject future
+  // upcoming frames.
+  void FallbackToSoftwareDecode();
+
+  // The "customer" of GpuJpegDecoder.
+  media::VideoCaptureDevice::Client* device_client_;
+  // The main working thread.
+  const scoped_refptr<base::MessageLoopProxy> main_task_runner_;
+  // The underlying JPEG decode accelerator.
+  scoped_ptr<media::JpegDecodeAccelerator> decoder_;
+
+  // Below fields are protected by |lock_|.
+  base::Lock lock_;
+
+  FailState fail_state_;
+
+  // Keep the captured data from camera. If hardware decode failed, pass this
+  // to software decoder as fallback.
+  CapturedData captured_data_;
+
+  // 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_;
+
+  // Buffer to hold decoded output of JPEG decoder.
+  // |out_frame_| is backed by this.
+  scoped_refptr<media::VideoCaptureDevice::Client::Buffer> out_buffer_;
+  // VideoFrame to receive decoded output of JpegDecodeAccelerator.
+  scoped_refptr<media::VideoFrame> out_frame_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuJpegDecoder);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_GPU_JPEG_DECODER_H_