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// 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.
// Also, all methods must be called on a valid COM thread. This can be done
// by using the base::win::ScopedCOMInitializer helper class.
#include <audioclient.h>
#include <mmdeviceapi.h>
#include <string>
#include "base/basictypes.h"
#include "base/time/time.h"
#include "base/win/scoped_comptr.h"
#include "media/audio/audio_device_name.h"
#include "media/audio/audio_parameters.h"
#include "media/base/media_export.h"
using base::win::ScopedComPtr;
namespace media {
// Represents audio channel configuration constants as understood by Windows.
// E.g. KSAUDIO_SPEAKER_MONO. For a list of possible values see:
typedef uint32 ChannelConfig;
class MEDIA_EXPORT CoreAudioUtil {
// Returns true if Windows Core Audio is supported.
// Always verify that this method returns true before using any of the
// methods in this class.
static bool IsSupported();
// Converts between reference time to base::TimeDelta.
// One reference-time unit is 100 nanoseconds.
// Example: double s = RefererenceTimeToTimeDelta(t).InMillisecondsF();
static base::TimeDelta RefererenceTimeToTimeDelta(REFERENCE_TIME time);
// Returns AUDCLNT_SHAREMODE_EXCLUSIVE if --enable-exclusive-mode is used
// as command-line flag and AUDCLNT_SHAREMODE_SHARED otherwise (default).
static AUDCLNT_SHAREMODE GetShareMode();
// 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 retrieve the total number of active audio
// devices.
static int NumberOfActiveDevices(EDataFlow data_flow);
// Creates an IMMDeviceEnumerator interface which provides methods for
// enumerating audio endpoint devices.
static ScopedComPtr<IMMDeviceEnumerator> CreateDeviceEnumerator();
// Creates a default endpoint device that is specified by a data-flow
// direction and role, e.g. default render device.
static ScopedComPtr<IMMDevice> CreateDefaultDevice(
EDataFlow data_flow, ERole role);
// Returns the device id of the default output device or an empty string
// if no such device exists or if the default device has been disabled.
static std::string GetDefaultOutputDeviceID();
// Creates an endpoint device that is specified by a unique endpoint device-
// identification string.
static ScopedComPtr<IMMDevice> CreateDevice(const std::string& device_id);
// Returns the unique ID and user-friendly name of a given endpoint device.
// Example: "{}.{8db6020f-18e3-4f25-b6f5-7726c9122574}", and
// "Microphone (Realtek High Definition Audio)".
static HRESULT GetDeviceName(IMMDevice* device, AudioDeviceName* name);
// Returns the device ID/path of the controller (a.k.a. physical device that
// |device| is connected to. This ID will be the same for all devices from
// the same controller so it is useful for doing things like determining
// whether a set of output and input devices belong to the same controller.
// The device enumerator is required as well as the device itself since
// looking at the device topology is required and we need to open up
// associated devices to determine the controller id.
// If the ID could not be determined for some reason, an empty string is
// returned.
static std::string GetAudioControllerID(IMMDevice* device,
IMMDeviceEnumerator* enumerator);
// Accepts an id of an input device and finds a matching output device id.
// If the associated hardware does not have an audio output device (e.g.
// a webcam with a mic), an empty string is returned.
static std::string GetMatchingOutputDeviceID(
const std::string& input_device_id);
// Gets the user-friendly name of the endpoint device which is represented
// by a unique id in |device_id|.
static std::string GetFriendlyName(const std::string& device_id);
// Returns true if the provided unique |device_id| corresponds to the current
// default device for the specified by a data-flow direction and role.
static bool DeviceIsDefault(
EDataFlow flow, ERole role, const std::string& device_id);
// Query if the audio device is a rendering device or a capture device.
static EDataFlow GetDataFlow(IMMDevice* device);
// 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 instance for the default IMMDevice where
// flow direction and role is define by |data_flow| and |role|.
// 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).
static ScopedComPtr<IAudioClient> CreateDefaultClient(EDataFlow data_flow,
ERole role);
// Create an IAudioClient instance for a specific device _or_ the default
// device if |device_id| is empty.
static ScopedComPtr<IAudioClient> CreateClient(const std::string& device_id,
EDataFlow data_flow,
ERole role);
// Create an IAudioClient interface for an existing IMMDevice given by
// |audio_device|. Flow direction and role is define by the |audio_device|.
static ScopedComPtr<IAudioClient> CreateClient(IMMDevice* audio_device);
// Get the mix format that the audio engine uses internally for processing
// of shared-mode streams. This format is not necessarily a format that the
// audio endpoint device supports. Thus, the caller might not succeed in
// creating an exclusive-mode stream with a format obtained by this method.
static HRESULT GetSharedModeMixFormat(IAudioClient* client,
// Returns true if the specified |client| supports the format in |format|
// for the given |share_mode| (shared or exclusive).
static bool IsFormatSupported(IAudioClient* client,
const WAVEFORMATPCMEX* format);
// Returns true if the specified |channel_layout| is supported for the
// default IMMDevice where flow direction and role is define by |data_flow|
// and |role|. If this method returns true for a certain channel layout, it
// means that SharedModeInitialize() will succeed using a format based on
// the preferred format where the channel layout has been modified.
static bool IsChannelLayoutSupported(const std::string& device_id,
EDataFlow data_flow,
ERole role,
ChannelLayout channel_layout);
// For a shared-mode stream, the audio engine periodically processes the
// data in the endpoint buffer at the period obtained in |device_period|.
// For an exclusive mode stream, |device_period| corresponds to the minimum
// time interval between successive processing by the endpoint device.
// This period plus the stream latency between the buffer and endpoint device
// represents the minimum possible latency that an audio application can
// achieve. The time in |device_period| is expressed in 100-nanosecond units.
static HRESULT GetDevicePeriod(IAudioClient* client,
REFERENCE_TIME* device_period);
// Get the preferred audio parameters for the specified |client| or the
// given direction and role is define by |data_flow| and |role|, or the
// unique device id given by |device_id|.
// The acquired values should only be utilized for shared mode streamed since
// there are no preferred settings for an exclusive mode stream.
static HRESULT GetPreferredAudioParameters(IAudioClient* client,
AudioParameters* params);
static HRESULT GetPreferredAudioParameters(EDataFlow data_flow, ERole role,
AudioParameters* params);
static HRESULT GetPreferredAudioParameters(const std::string& device_id,
AudioParameters* params);
// Retrieves an integer mask which corresponds to the channel layout the
// audio engine uses for its internal processing/mixing of shared-mode
// streams. This mask indicates which channels are present in the multi-
// channel stream. The least significant bit corresponds with the Front Left
// speaker, the next least significant bit corresponds to the Front Right
// speaker, and so on, continuing in the order defined in KsMedia.h.
// See
// for more details.
// To get the channel config of the default device, pass an empty string
// for |device_id|.
static ChannelConfig GetChannelConfig(const std::string& device_id,
EDataFlow data_flow);
// After activating an IAudioClient interface on an audio endpoint device,
// the client must initialize it once, and only once, to initialize the audio
// stream between the client and the device. In shared mode, the client
// connects indirectly through the audio engine which does the mixing.
// In exclusive mode, the client connects directly to the audio hardware.
// If a valid event is provided in |event_handle|, the client will be
// initialized for event-driven buffer handling. If |event_handle| is set to
// NULL, event-driven buffer handling is not utilized.
static HRESULT SharedModeInitialize(IAudioClient* client,
const WAVEFORMATPCMEX* format,
HANDLE event_handle,
uint32* endpoint_buffer_size);
// TODO(henrika): add ExclusiveModeInitialize(...)
// Create an IAudioRenderClient client for an existing IAudioClient given by
// |client|. The IAudioRenderClient interface enables a client to write
// output data to a rendering endpoint buffer.
static ScopedComPtr<IAudioRenderClient> CreateRenderClient(
IAudioClient* client);
// Create an IAudioCaptureClient client for an existing IAudioClient given by
// |client|. The IAudioCaptureClient interface enables a client to read
// input data from a capture endpoint buffer.
static ScopedComPtr<IAudioCaptureClient> CreateCaptureClient(
IAudioClient* client);
// Fills up the endpoint rendering buffer with silence for an existing
// IAudioClient given by |client| and a corresponding IAudioRenderClient
// given by |render_client|.
static bool FillRenderEndpointBufferWithSilence(
IAudioClient* client, IAudioRenderClient* render_client);
CoreAudioUtil() {}
~CoreAudioUtil() {}
} // namespace media