media/capture/video/linux/video_capture_device_linux.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // Linux specific implementation of VideoCaptureDevice.
   6 // V4L2 is used for capturing. V4L2 does not provide its own thread for
   7 // capturing so this implementation uses a Chromium thread for fetching frames
   8 // from V4L2.
   9
  10 #ifndef MEDIA_VIDEO_CAPTURE_LINUX_VIDEO_CAPTURE_DEVICE_LINUX_H_
  11 #define MEDIA_VIDEO_CAPTURE_LINUX_VIDEO_CAPTURE_DEVICE_LINUX_H_
  12
  13 #include <string>
  14
  15 #include "base/files/file_util.h"
  16 #include "base/files/scoped_file.h"
  17 #include "base/threading/thread.h"
  18 #include "media/base/video_capture_types.h"
  19 #include "media/capture/video/video_capture_device.h"
  20
  21 namespace media {
  22
  23 class V4L2CaptureDelegate;
  24
  25 // Linux V4L2 implementation of VideoCaptureDevice.
  26 class VideoCaptureDeviceLinux : public VideoCaptureDevice {
  27  public:
  28   static VideoCapturePixelFormat V4l2FourCcToChromiumPixelFormat(
  29       uint32 v4l2_fourcc);
  30   static std::list<uint32_t> GetListOfUsableFourCCs(bool favour_mjpeg);
  31
  32   explicit VideoCaptureDeviceLinux(const Name& device_name);
  33   ~VideoCaptureDeviceLinux() override;
  34
  35   // VideoCaptureDevice implementation.
  36   void AllocateAndStart(const VideoCaptureParams& params,
  37                         scoped_ptr<Client> client) override;
  38   void StopAndDeAllocate() override;
  39
  40  protected:
  41   void SetRotation(int rotation);
  42
  43  private:
  44   static int TranslatePowerLineFrequencyToV4L2(int frequency);
  45
  46   // Internal delegate doing the actual capture setting, buffer allocation and
  47   // circulacion with the V4L2 API. Created and deleted in the thread where
  48   // VideoCaptureDeviceLinux lives but otherwise operating on |v4l2_thread_|.
  49   scoped_refptr<V4L2CaptureDelegate> capture_impl_;
  50
  51   base::Thread v4l2_thread_;  // Thread used for reading data from the device.
  52
  53   const Name device_name_;
  54
  55   DISALLOW_IMPLICIT_CONSTRUCTORS(VideoCaptureDeviceLinux);
  56 };
  57
  58 }  // namespace media
  59
  60 #endif  // MEDIA_VIDEO_CAPTURE_LINUX_VIDEO_CAPTURE_DEVICE_LINUX_H_