Adds Core Audio Utility methods for Windows

media/audio/win/core_audio_util_win.h

+// 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.
+
+// TODO(henrika): add comments....
+
+// MMDevice API
+// The Windows Multimedia Device (MMDevice) API enables audio clients to
+// discover audio endpoint devices and determine their capabilities.
+//
+// WASAPI
+// The Windows Audio Session API (WASAPI) enables client applications to
+// manage the flow of audio data between the application and an audio endpoint
+// device.
+//
+// DeviceTopology API
+// Clients use this API to directly access the topological features
+// (for example, volume controls and multiplexers) that lie along the data
+// paths inside hardware devices in audio adapters.
+//
+// EndpointVolume API.
+// Clients use this API to directly access the volume controls on audio
+// endpoint devices. This API is primarily used by applications that manage
+// exclusive-mode audio streams.
+
+#ifndef MEDIA_AUDIO_WIN_CORE_AUDIO_UTIL_WIN_H_
+#define MEDIA_AUDIO_WIN_CORE_AUDIO_UTIL_WIN_H_
+
+#include <audioclient.h>
+#include <mmdeviceapi.h>
+#include <string>
+
+#include "base/basictypes.h"
+#include "base/win/scoped_comptr.h"
+#include "media/audio/audio_device_name.h"
+#include "media/base/media_export.h"
+
+using base::win::ScopedComPtr;
+
+namespace media {
+namespace win {

[scherkus (not reviewing), 2012/10/23 20:57:55]

jam@ has a preference to avoid nested namespaces, preferring class scoping
instead.

[henrika (OOO until Aug 14), 2012/10/24 13:50:28]

I will remove win namespace and modify signatures. Would really like to avoid
creating a separate class only to add static members just to emulate a nested
namespace. Hope you are OK with the new approach.

+
+// Returns true if Windows Core Audio is supported.
+MEDIA_EXPORT bool CoreAudioIsSupported();

[scherkus (not reviewing), 2012/10/23 20:57:55]

if this returns false will some of the methods below not be callable?

[henrika (OOO until Aug 14), 2012/10/24 13:50:28]

Good point. Added DCHECKs in all methods.

+
+// --- MMDevice
+
+// Number of active audio devices in the specified flow data flow direction.
+// Set |data_flow| to eAll to retrive the total number of active audio devices.
+MEDIA_EXPORT int NumberOfActiveAudioDevices(EDataFlow data_flow);
+
+// Creates an IMMDeviceEnumerator interface which provides methods for
+// enumerating audio endpoint devices.
+MEDIA_EXPORT ScopedComPtr<IMMDeviceEnumerator> CreateDeviceEnumerator();
+
+// Create a default endpoint device that is specified by a data-flow
+// direction and role, e.g. default render device.
+MEDIA_EXPORT ScopedComPtr<IMMDevice> CreateDefaultAudioDevice(
+    EDataFlow data_flow, ERole role);
+
+// Create an endpoint device that is specified by a unique endpoint device-
+// identification string.
+MEDIA_EXPORT ScopedComPtr<IMMDevice> CreateAudioDevice(
+    const std::string& device_id);
+
+// Returns the unique ID and user-friendly name of a given endpoint device.
+// Example: "{0.0.1.00000000}.{8db6020f-18e3-4f25-b6f5-7726c9122574}", and
+//          "Microphone (Realtek High Definition Audio)".
+MEDIA_EXPORT HRESULT GetAudioDeviceName(IMMDevice* device,
+                                        AudioDeviceName* name);
+
+// Gets the user-friendly name of the endpoint devcice which is represented
+// by a uniqe id in |device_id|.
+MEDIA_EXPORT std::string GetFriendlyName(const std::string& device_id);
+
+// Returns true if the provided uniqe |device_id| correspinds to the current
+// default device for the specified by a data-flow direction and role.
+MEDIA_EXPORT bool IsDeviceDefault(EDataFlow flow, ERole role,
+                                  std::string device_id);
+
+// Query if the audio endpoint device is a rendering device or a capture device.
+MEDIA_EXPORT EDataFlow GetDataFlow(IMMDevice* device);
+
+// --- WASAPI
+
+// Create an IAudioClient interface for an existing IMMDevice given by
+// |audio_device|. Flow direction and role is define by the |audio_device|.
+// The IAudioClient interface enables a client to create and initialize an
+// audio stream between an audio application and the audio engine (for a
+// shared-mode stream) or the hardware buffer of an audio endpoint device
+// (for an exclusive-mode stream).
+MEDIA_EXPORT ScopedComPtr<IAudioClient> CreateAudioClient(
+    IMMDevice* audio_device);
+
+}  // namespace win
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_WIN_CORE_AUDIO_UTIL_WIN_H_