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.
+
+// Utility methods for the Core Audio API on Windows.
+// Always ensure that Core Audio is supported before using these methods.
+// Use media::CoreAudioIsSupported() for this purpose.
+
+#ifndef MEDIA_AUDIO_WIN_CORE_AUDIO_UTIL_WIN_H_

[scherkus (not reviewing), 2012/10/24 16:48:04]

nit: it's your call but we don't have to add a _win.h/cc suffix -- the
windows-exclusivity of this file is already covered by being in a win/ subfolder
:)

[henrika (OOO until Aug 14), 2012/10/24 19:25:44]

Got it. I actually think that I followed lint here.

[tommi (sloooow) - chröme, 2012/10/29 10:45:26]

Lint was pointing out that the #if guard must match the file name.  I think
Andrew is saying that the file name doesn't need to have the _win postfix since
it's already in a windows-only folder.

However, I checked the other files in this folder and see that they all have the
_win postfix, so I think it's more consistent to keep the file names as they
are.

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

[scherkus (not reviewing), 2012/10/24 16:48:04]

I find this comment is redundant given the one immediately below this one

[henrika (OOO until Aug 14), 2012/10/24 19:25:44]

Will modify.

[henrika (OOO until Aug 14), 2012/10/25 15:14:08]

Done.

+
+// The Windows Multimedia Device (MMDevice) API enables audio clients to
+// discover audio endpoint devices and determine their capabilities.
+
+// 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 CoreAudioNumberOfActiveDevices(EDataFlow data_flow);

[DaleCurtis, 2012/10/25 01:08:08]

kind of stinks to have to prefix all these with CoreAudio! Are you sure you
don't want to wrap them in a CoreAudio class?

CoreAudioUtil::NumberOfActiveDevices() looks good.

[henrika (OOO until Aug 14), 2012/10/25 15:14:08]

Agree. That is why I started out with a nested namespace. Anyhow, I'll create a
class with only static members.

+
+// Creates an IMMDeviceEnumerator interface which provides methods for
+// enumerating audio endpoint devices.
+MEDIA_EXPORT ScopedComPtr<IMMDeviceEnumerator>
+    CoreAudioCreateDeviceEnumerator();
+
+// Create a default endpoint device that is specified by a data-flow
+// direction and role, e.g. default render device.
+MEDIA_EXPORT ScopedComPtr<IMMDevice> CoreAudioCreateDefaultDevice(
+    EDataFlow data_flow, ERole role);
+
+// Create an endpoint device that is specified by a unique endpoint device-
+// identification string.
+MEDIA_EXPORT ScopedComPtr<IMMDevice> CoreAudioCreateDevice(
+    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 CoreAudioGetDeviceName(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 CoreAudioGetFriendlyName(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 CoreAudioDeviceIsDefault(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 CoreAudioGetDataFlow(IMMDevice* device);
+
+// --- WASAPI

[scherkus (not reviewing), 2012/10/24 16:48:04]

ditto

[henrika (OOO until Aug 14), 2012/10/24 19:25:44]

Will modify.

[henrika (OOO until Aug 14), 2012/10/25 15:14:08]

Done.

+
+// The Windows Audio Session API (WASAPI) enables client applications to
+// manage the flow of audio data between the application and an audio endpoint
+// device.
+
+// 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> CoreAudioCreateClient(
+    IMMDevice* audio_device);
+
+// TODO(henrika): add more methods here...

[scherkus (not reviewing), 2012/10/24 16:48:04]

this isn't very descriptive -- I'd either have it filled out or simply remove it
as no one other than you knows what to add :)

[henrika (OOO until Aug 14), 2012/10/24 19:25:44]

Agree. Will delete.

+
+}  // namespace media
+
+#endif  // MEDIA_AUDIO_WIN_CORE_AUDIO_UTIL_WIN_H_