core_audio_util_win.h revision 5821806d5e7f356e8fa4b058a389a808ea183019 
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// Utility methods for the Core Audio API on Windows.
6// Always ensure that Core Audio is supported before using these methods.
7// Use media::CoreAudioIsSupported() for this purpose.
8
9#ifndef MEDIA_AUDIO_WIN_CORE_AUDIO_UTIL_WIN_H_
10#define MEDIA_AUDIO_WIN_CORE_AUDIO_UTIL_WIN_H_
11
12#include <audioclient.h>
13#include <mmdeviceapi.h>
14#include <string>
15
16#include "base/basictypes.h"
17#include "base/win/scoped_comptr.h"
18#include "media/audio/audio_device_name.h"
19#include "media/base/media_export.h"
20
21using base::win::ScopedComPtr;
22
23namespace media {
24
25class MEDIA_EXPORT CoreAudioUtil {
26 public:
27  // Returns true if Windows Core Audio is supported.
28  static bool IsSupported();
29
30  // The Windows Multimedia Device (MMDevice) API enables audio clients to
31  // discover audio endpoint devices and determine their capabilities.
32
33  // Number of active audio devices in the specified flow data flow direction.
34  // Set |data_flow| to eAll to retrive the total number of active audio
35  // devices.
36  static int NumberOfActiveDevices(EDataFlow data_flow);
37
38  // Creates an IMMDeviceEnumerator interface which provides methods for
39  // enumerating audio endpoint devices.
40  static ScopedComPtr<IMMDeviceEnumerator> CreateDeviceEnumerator();
41
42  // Create a default endpoint device that is specified by a data-flow
43  // direction and role, e.g. default render device.
44  static ScopedComPtr<IMMDevice> CreateDefaultDevice(
45      EDataFlow data_flow, ERole role);
46
47  // Create an endpoint device that is specified by a unique endpoint device-
48  // identification string.
49  static ScopedComPtr<IMMDevice> CreateDevice(const std::string& device_id);
50
51  // Returns the unique ID and user-friendly name of a given endpoint device.
52  // Example: "{0.0.1.00000000}.{8db6020f-18e3-4f25-b6f5-7726c9122574}", and
53  //          "Microphone (Realtek High Definition Audio)".
54  static HRESULT GetDeviceName(IMMDevice* device, AudioDeviceName* name);
55
56  // Gets the user-friendly name of the endpoint devcice which is represented
57  // by a uniqe id in |device_id|.
58  static std::string GetFriendlyName(const std::string& device_id);
59
60  // Returns true if the provided uniqe |device_id| correspinds to the current
61  // default device for the specified by a data-flow direction and role.
62  static bool DeviceIsDefault(
63      EDataFlow flow, ERole role, std::string device_id);
64
65  // Query if the audio device is a rendering device or a capture device.
66  static EDataFlow GetDataFlow(IMMDevice* device);
67
68  // The Windows Audio Session API (WASAPI) enables client applications to
69  // manage the flow of audio data between the application and an audio endpoint
70  // device.
71
72  // Create an IAudioClient interface for an existing IMMDevice given by
73  // |audio_device|. Flow direction and role is define by the |audio_device|.
74  // The IAudioClient interface enables a client to create and initialize an
75  // audio stream between an audio application and the audio engine (for a
76  // shared-mode stream) or the hardware buffer of an audio endpoint device
77  // (for an exclusive-mode stream).
78  static ScopedComPtr<IAudioClient> CreateClient(IMMDevice* audio_device);
79
80 private:
81  CoreAudioUtil() {}
82  ~CoreAudioUtil() {}
83  DISALLOW_COPY_AND_ASSIGN(CoreAudioUtil);
84};
85
86}  // namespace media
87
88#endif  // MEDIA_AUDIO_WIN_CORE_AUDIO_UTIL_WIN_H_
89