// Copyright (c) 2012 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.
//
// VideoCaptureDevice is the abstract base class for realizing video capture
// device support in Chromium. It provides the interface for OS dependent
// implementations.
// The class is created and functions are invoked on a thread owned by
// VideoCaptureManager. Capturing is done on other threads, depending on the OS
// specific implementation.
#ifndef MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_
#define MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_
#include <list>
#include <string>
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/time/time.h"
#include "media/base/media_export.h"
#include "media/base/video_frame.h"
#include "media/video/capture/video_capture_types.h"
namespace media {
class MEDIA_EXPORT VideoCaptureDevice {
public:
// Represents a capture device name and ID.
// You should not create an instance of this class directly by e.g. setting
// various properties directly. Instead use
// VideoCaptureDevice::GetDeviceNames to do this for you and if you need to
// cache your own copy of a name, you can do so via the copy constructor.
// The reason for this is that a device name might contain platform specific
// settings that are relevant only to the platform specific implementation of
// VideoCaptureDevice::Create.
class MEDIA_EXPORT Name {
public:
Name() {}
Name(const std::string& name, const std::string& id)
: device_name_(name), unique_id_(id) {}
#if defined(OS_WIN)
// Windows targets Capture Api type: it can only be set on construction.
enum CaptureApiType {
MEDIA_FOUNDATION,
DIRECT_SHOW,
API_TYPE_UNKNOWN
};
Name(const std::string& name,
const std::string& id,
const CaptureApiType api_type)
: device_name_(name), unique_id_(id), capture_api_class_(api_type) {}
#endif // if defined(OS_WIN)
~Name() {}
// Friendly name of a device
const std::string& name() const { return device_name_; }
// Unique name of a device. Even if there are multiple devices with the same
// friendly name connected to the computer this will be unique.
const std::string& id() const { return unique_id_; }
// The unique hardware model identifier of the capture device. Returns
// "[vid]:[pid]" when a USB device is detected, otherwise "".
// The implementation of this method is platform-dependent.
const std::string GetModel() const;
// Friendly name of a device, plus the model identifier in parentheses.
const std::string GetNameAndModel() const;
// These operators are needed due to storing the name in an STL container.
// In the shared build, all methods from the STL container will be exported
// so even though they're not used, they're still depended upon.
bool operator==(const Name& other) const {
return other.id() == unique_id_;
}
bool operator<(const Name& other) const {
return unique_id_ < other.id();
}
#if defined(OS_WIN)
CaptureApiType capture_api_type() const {
return capture_api_class_.capture_api_type();
}
#endif // if defined(OS_WIN)
private:
std::string device_name_;
std::string unique_id_;
#if defined(OS_WIN)
// This class wraps the CaptureApiType, so it has a by default value if not
// inititalized, and I (mcasas) do a DCHECK on reading its value.
class CaptureApiClass {
public:
CaptureApiClass(): capture_api_type_(API_TYPE_UNKNOWN) {}
CaptureApiClass(const CaptureApiType api_type)
: capture_api_type_(api_type) {}
CaptureApiType capture_api_type() const {
DCHECK_NE(capture_api_type_, API_TYPE_UNKNOWN);
return capture_api_type_;
}
private:
CaptureApiType capture_api_type_;
};
CaptureApiClass capture_api_class_;
#endif // if defined(OS_WIN)
// Allow generated copy constructor and assignment.
};
// Manages a list of Name entries.
typedef std::list<Name> Names;
class MEDIA_EXPORT Client {
public:
// Memory buffer returned by Client::ReserveOutputBuffer().
class Buffer : public base::RefCountedThreadSafe<Buffer> {
public:
int id() const { return id_; }
void* data() const { return data_; }
size_t size() const { return size_; }
protected:
friend class base::RefCountedThreadSafe<Buffer>;
Buffer(int id, void* data, size_t size)
: id_(id), data_(data), size_(size) {}
virtual ~Buffer() {}
const int id_;
void* const data_;
const size_t size_;
};
virtual ~Client() {}
// Reserve an output buffer into which contents can be captured directly.
// The returned Buffer will always be allocated with a memory size suitable
// for holding a packed video frame with pixels of |format| format, of
// |dimensions| frame dimensions. It is permissible for |dimensions| to be
// zero; in which case the returned Buffer does not guarantee memory
// backing, but functions as a reservation for external input for the
// purposes of buffer throttling.
//
// The output buffer stays reserved for use until the Buffer object is
// destroyed.
virtual scoped_refptr<Buffer> ReserveOutputBuffer(
media::VideoFrame::Format format,
const gfx::Size& dimensions) = 0;
// Captured a new video frame, data for which is pointed to by |data|.
//
// The format of the frame is described by |frame_format|, and is assumed to
// be tightly packed. This method will try to reserve an output buffer and
// copy from |data| into the output buffer. If no output buffer is
// available, the frame will be silently dropped.
virtual void OnIncomingCapturedData(const uint8* data,
int length,
const VideoCaptureFormat& frame_format,
int rotation, // Clockwise.
base::TimeTicks timestamp) = 0;
// Captured a new video frame, held in |frame|.
//
// As the frame is backed by a reservation returned by
// ReserveOutputBuffer(), delivery is guaranteed and will require no
// additional copies in the browser process.
virtual void OnIncomingCapturedVideoFrame(
const scoped_refptr<Buffer>& buffer,
const VideoCaptureFormat& buffer_format,
const scoped_refptr<media::VideoFrame>& frame,
base::TimeTicks timestamp) = 0;
// An error has occurred that cannot be handled and VideoCaptureDevice must
// be StopAndDeAllocate()-ed. |reason| is a text description of the error.
virtual void OnError(const std::string& reason) = 0;
};
// Creates a VideoCaptureDevice object.
// Return NULL if the hardware is not available.
static VideoCaptureDevice* Create(const Name& device_name);
virtual ~VideoCaptureDevice();
// Gets the names of all video capture devices connected to this computer.
static void GetDeviceNames(Names* device_names);
// Gets the supported formats of a particular device attached to the system.
// This method should be called before allocating or starting a device. In
// case format enumeration is not supported, or there was a problem, the
// formats array will be empty.
static void GetDeviceSupportedFormats(const Name& device,
VideoCaptureFormats* supported_formats);
// Prepares the camera for use. After this function has been called no other
// applications can use the camera. StopAndDeAllocate() must be called before
// the object is deleted.
virtual void AllocateAndStart(const VideoCaptureParams& params,
scoped_ptr<Client> client) = 0;
// Deallocates the camera, possibly asynchronously.
//
// This call requires the device to do the following things, eventually: put
// camera hardware into a state where other applications could use it, free
// the memory associated with capture, and delete the |client| pointer passed
// into AllocateAndStart.
//
// If deallocation is done asynchronously, then the device implementation must
// ensure that a subsequent AllocateAndStart() operation targeting the same ID
// would be sequenced through the same task runner, so that deallocation
// happens first.
virtual void StopAndDeAllocate() = 0;
};
} // namespace media
#endif // MEDIA_VIDEO_CAPTURE_VIDEO_CAPTURE_DEVICE_H_