media/video/capture/video_capture_device.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 // VideoCaptureDevice is the abstract base class for realizing video capture
   6 // device support in Chromium. It provides the interface for OS dependent
   7 // implementations.
   8 // The class is created and functions are invoked on a thread owned by
   9 // VideoCaptureManager. Capturing is done on other threads, depending on the OS
  10 // specific implementation.
  11
  12 #ifndef MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_
  13 #define MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_
  14
  15 #include <list>
  16 #include <string>
  17
  18 #include "base/logging.h"
  19 #include "base/memory/ref_counted.h"
  20 #include "base/memory/scoped_ptr.h"
  21 #include "base/single_thread_task_runner.h"
  22 #include "base/time/time.h"
  23 #include "media/base/media_export.h"
  24 #include "media/base/video_frame.h"
  25 #include "media/video/capture/video_capture_types.h"
  26
  27 namespace media {
  28
  29 class MEDIA_EXPORT VideoCaptureDevice {
  30  public:
  31   // Represents a capture device name and ID.
  32   // You should not create an instance of this class directly by e.g. setting
  33   // various properties directly.  Instead use
  34   // VideoCaptureDevice::GetDeviceNames to do this for you and if you need to
  35   // cache your own copy of a name, you can do so via the copy constructor.
  36   // The reason for this is that a device name might contain platform specific
  37   // settings that are relevant only to the platform specific implementation of
  38   // VideoCaptureDevice::Create.
  39   class MEDIA_EXPORT Name {
  40    public:
  41     Name() {}
  42     Name(const std::string& name, const std::string& id)
  43         : device_name_(name), unique_id_(id) {}
  44
  45 #if defined(OS_WIN)
  46     // Windows targets Capture Api type: it can only be set on construction.
  47     enum CaptureApiType {
  48       MEDIA_FOUNDATION,
  49       DIRECT_SHOW,
  50       API_TYPE_UNKNOWN
  51     };
  52 #endif
  53 #if defined(OS_MACOSX)
  54     // Mac targets Capture Api type: it can only be set on construction.
  55     enum CaptureApiType {
  56       AVFOUNDATION,
  57       QTKIT,
  58       API_TYPE_UNKNOWN
  59     };
  60 #endif
  61 #if defined(OS_WIN) || defined(OS_MACOSX)
  62     Name(const std::string& name,
  63          const std::string& id,
  64          const CaptureApiType api_type)
  65         : device_name_(name), unique_id_(id), capture_api_class_(api_type) {}
  66 #endif
  67     ~Name() {}
  68
  69     // Friendly name of a device
  70     const std::string& name() const { return device_name_; }
  71
  72     // Unique name of a device. Even if there are multiple devices with the same
  73     // friendly name connected to the computer this will be unique.
  74     const std::string& id() const { return unique_id_; }
  75
  76     // The unique hardware model identifier of the capture device. Returns
  77     // "[vid]:[pid]" when a USB device is detected, otherwise "".
  78     // The implementation of this method is platform-dependent.
  79     const std::string GetModel() const;
  80
  81     // Friendly name of a device, plus the model identifier in parentheses.
  82     const std::string GetNameAndModel() const;
  83
  84     // These operators are needed due to storing the name in an STL container.
  85     // In the shared build, all methods from the STL container will be exported
  86     // so even though they're not used, they're still depended upon.
  87     bool operator==(const Name& other) const {
  88       return other.id() == unique_id_;
  89     }
  90     bool operator<(const Name& other) const {
  91       return unique_id_ < other.id();
  92     }
  93
  94 #if defined(OS_WIN) || defined(OS_MACOSX)
  95     CaptureApiType capture_api_type() const {
  96       return capture_api_class_.capture_api_type();
  97     }
  98 #endif  // if defined(OS_WIN)
  99
 100    private:
 101     std::string device_name_;
 102     std::string unique_id_;
 103 #if defined(OS_WIN) || defined(OS_MACOSX)
 104     // This class wraps the CaptureApiType to give it a by default value if not
 105     // initialized.
 106     class CaptureApiClass {
 107      public:
 108       CaptureApiClass(): capture_api_type_(API_TYPE_UNKNOWN) {}
 109       CaptureApiClass(const CaptureApiType api_type)
 110           : capture_api_type_(api_type) {}
 111       CaptureApiType capture_api_type() const {
 112         DCHECK_NE(capture_api_type_, API_TYPE_UNKNOWN);
 113         return capture_api_type_;
 114       }
 115      private:
 116       CaptureApiType capture_api_type_;
 117     };
 118
 119     CaptureApiClass capture_api_class_;
 120 #endif
 121     // Allow generated copy constructor and assignment.
 122   };
 123
 124   // Manages a list of Name entries.
 125   typedef std::list<Name> Names;
 126
 127   class MEDIA_EXPORT Client {
 128    public:
 129     // Memory buffer returned by Client::ReserveOutputBuffer().
 130     class Buffer : public base::RefCountedThreadSafe<Buffer> {
 131      public:
 132       int id() const { return id_; }
 133       void* data() const { return data_; }
 134       size_t size() const { return size_; }
 135
 136      protected:
 137       friend class base::RefCountedThreadSafe<Buffer>;
 138
 139       Buffer(int id, void* data, size_t size)
 140           : id_(id), data_(data), size_(size) {}
 141       virtual ~Buffer() {}
 142
 143       const int id_;
 144       void* const data_;
 145       const size_t size_;
 146     };
 147
 148     virtual ~Client() {}
 149
 150     // Reserve an output buffer into which contents can be captured directly.
 151     // The returned Buffer will always be allocated with a memory size suitable
 152     // for holding a packed video frame with pixels of |format| format, of
 153     // |dimensions| frame dimensions. It is permissible for |dimensions| to be
 154     // zero; in which case the returned Buffer does not guarantee memory
 155     // backing, but functions as a reservation for external input for the
 156     // purposes of buffer throttling.
 157     //
 158     // The output buffer stays reserved for use until the Buffer object is
 159     // destroyed.
 160     virtual scoped_refptr<Buffer> ReserveOutputBuffer(
 161         media::VideoFrame::Format format,
 162         const gfx::Size& dimensions) = 0;
 163
 164     // Captured a new video frame, data for which is pointed to by |data|.
 165     //
 166     // The format of the frame is described by |frame_format|, and is assumed to
 167     // be tightly packed. This method will try to reserve an output buffer and
 168     // copy from |data| into the output buffer. If no output buffer is
 169     // available, the frame will be silently dropped.
 170     virtual void OnIncomingCapturedData(const uint8* data,
 171                                         int length,
 172                                         const VideoCaptureFormat& frame_format,
 173                                         int rotation,  // Clockwise.
 174                                         base::TimeTicks timestamp) = 0;
 175
 176     // Captured a new video frame, held in |frame|.
 177     //
 178     // As the frame is backed by a reservation returned by
 179     // ReserveOutputBuffer(), delivery is guaranteed and will require no
 180     // additional copies in the browser process.
 181     virtual void OnIncomingCapturedVideoFrame(
 182         const scoped_refptr<Buffer>& buffer,
 183         const VideoCaptureFormat& buffer_format,
 184         const scoped_refptr<media::VideoFrame>& frame,
 185         base::TimeTicks timestamp) = 0;
 186
 187     // An error has occurred that cannot be handled and VideoCaptureDevice must
 188     // be StopAndDeAllocate()-ed. |reason| is a text description of the error.
 189     virtual void OnError(const std::string& reason) = 0;
 190
 191     // VideoCaptureDevice requests the |message| to be logged.
 192     virtual void OnLog(const std::string& message) {}
 193   };
 194
 195   // Creates a VideoCaptureDevice object.
 196   // Return NULL if the hardware is not available.
 197   static VideoCaptureDevice* Create(
 198       scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner,
 199       const Name& device_name);
 200   virtual ~VideoCaptureDevice();
 201
 202   // Gets the names of all video capture devices connected to this computer.
 203   static void GetDeviceNames(Names* device_names);
 204
 205   // Gets the supported formats of a particular device attached to the system.
 206   // This method should be called before allocating or starting a device. In
 207   // case format enumeration is not supported, or there was a problem, the
 208   // formats array will be empty.
 209   static void GetDeviceSupportedFormats(const Name& device,
 210                                         VideoCaptureFormats* supported_formats);
 211
 212   // Prepares the camera for use. After this function has been called no other
 213   // applications can use the camera. StopAndDeAllocate() must be called before
 214   // the object is deleted.
 215   virtual void AllocateAndStart(const VideoCaptureParams& params,
 216                                 scoped_ptr<Client> client) = 0;
 217
 218   // Deallocates the camera, possibly asynchronously.
 219   //
 220   // This call requires the device to do the following things, eventually: put
 221   // camera hardware into a state where other applications could use it, free
 222   // the memory associated with capture, and delete the |client| pointer passed
 223   // into AllocateAndStart.
 224   //
 225   // If deallocation is done asynchronously, then the device implementation must
 226   // ensure that a subsequent AllocateAndStart() operation targeting the same ID
 227   // would be sequenced through the same task runner, so that deallocation
 228   // happens first.
 229   virtual void StopAndDeAllocate() = 0;
 230
 231   // Gets the power line frequency from the current system time zone if this is
 232   // defined, otherwise returns 0.
 233   int GetPowerLineFrequencyForLocation() const;
 234
 235  protected:
 236   static const int kPowerLine50Hz = 50;
 237   static const int kPowerLine60Hz = 60;
 238 };
 239
 240 }  // namespace media
 241
 242 #endif  // MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_