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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::CoreAudioUtil::IsSupported() 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 <stdint.h>
#include <wrl/client.h>
#include <string>
#include "base/macros.h"
#include "base/time/time.h"
#include "media/audio/audio_device_name.h"
#include "media/base/audio_parameters.h"
#include "media/base/media_export.h"
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_t ChannelConfig;
class MEDIA_EXPORT CoreAudioUtil {
// Helper class which automates casting between WAVEFORMATEX and
// WAVEFORMATEXTENSIBLE raw pointers using implicit constructors and
// operator overloading. Note that, no memory is allocated by this utility
// structure. It only serves as a handle (or a wrapper) of the structure
// provided to it at construction.
class MEDIA_EXPORT WaveFormatWrapper {
: ptr_(reinterpret_cast<WAVEFORMATEX*>(p)) {}
WaveFormatWrapper(WAVEFORMATEX* p) : ptr_(p) {}
~WaveFormatWrapper() = default;
operator WAVEFORMATEX*() const { return ptr_; }
WAVEFORMATEX* operator->() const { return ptr_; }
WAVEFORMATEX* get() const { return ptr_; }
WAVEFORMATEXTENSIBLE* GetExtensible() const;
bool IsExtensible() const;
bool IsPcm() const;
bool IsFloat() const;
size_t size() const;
// Returns true if Windows Core Audio is supported.
// Always verify that this method returns true before using any of the
// methods in this class.
// WARNING: This function must be called once from the main thread before
// it is safe to call from other threads.
static bool IsSupported();
// Prints/logs all fields of the format structure in |format|.
// Also supports extended versions (WAVEFORMATEXTENSIBLE).
static std::string WaveFormatToString(WaveFormatWrapper format);
// Converts between reference time to base::TimeDelta.
// One reference-time unit is 100 nanoseconds.
// Example: double s = RefererenceTimeToTimeDelta(t).InMillisecondsF();
static base::TimeDelta ReferenceTimeToTimeDelta(REFERENCE_TIME time);
// Returns 1, 2, or 3 corresponding to the highest version of IAudioClient
// the platform supports.
static uint32_t GetIAudioClientVersion();
// 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 Microsoft::WRL::ComPtr<IMMDeviceEnumerator> CreateDeviceEnumerator();
// Create an endpoint device specified by |device_id| or a default device
// specified by data-flow direction and role if
// AudioDeviceDescription::IsDefaultDevice(|device_id|).
static Microsoft::WRL::ComPtr<IMMDevice>
CreateDevice(const std::string& device_id, EDataFlow data_flow, ERole role);
// These functions return the device id of the default or communications
// input/output device, or an empty string if no such device exists or if the
// device has been disabled.
static std::string GetDefaultInputDeviceID();
static std::string GetDefaultOutputDeviceID();
static std::string GetCommunicationsInputDeviceID();
static std::string GetCommunicationsOutputDeviceID();
// 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,
EDataFlow data_flow,
ERole role);
// 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 a specific device or the default
// device if AudioDeviceDescription::IsDefaultDevice(device_id).
static Microsoft::WRL::ComPtr<IAudioClient>
CreateClient(const std::string& device_id, EDataFlow data_flow, ERole role);
static Microsoft::WRL::ComPtr<IAudioClient3>
CreateClient3(const std::string& device_id, EDataFlow data_flow, ERole role);
// 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. The WAVEFORMATEXTENSIBLE structure can
// specify both the mapping of channels to speakers and the number of bits of
// precision in each sample. The first member of the WAVEFORMATEXTENSIBLE
// structure is a WAVEFORMATEX structure and its wFormatTag will be set to
// WAVE_FORMAT_EXTENSIBLE if the output structure is extended.
// FormatIsExtensible() can be used to determine if that is the case or not.
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,
WaveFormatWrapper 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 given |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(const std::string& device_id,
bool is_output_device,
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.
// This function will initialize the audio client as part of the default
// audio session if NULL is passed for |session_guid|, otherwise the client
// will be associated with the specified session.
static HRESULT SharedModeInitialize(IAudioClient* client,
WaveFormatWrapper format,
HANDLE event_handle,
uint32_t requested_buffer_size,
uint32_t* endpoint_buffer_size,
const GUID* session_guid);
// 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 Microsoft::WRL::ComPtr<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 Microsoft::WRL::ComPtr<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() {}
// The special audio session identifier we use when opening up the default
// communication device. This has the effect that a separate volume control
// will be shown in the system's volume mixer and control over ducking and
// visually observing the behavior of ducking, is easier.
// Use with |SharedModeInitialize|.
extern const GUID kCommunicationsSessionId;
} // namespace media