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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.
// Implementation of AudioInputStream for Windows using Windows Core Audio
// WASAPI for low latency capturing.
// Overview of operation:
// - An object of WASAPIAudioInputStream is created by the AudioManager
// factory.
// - Next some thread will call Open(), at that point the underlying
// Core Audio APIs are utilized to create two WASAPI interfaces called
// IAudioClient and IAudioCaptureClient.
// - Then some thread will call Start(sink).
// A thread called "wasapi_capture_thread" is started and this thread listens
// on an event signal which is set periodically by the audio engine for
// each recorded data packet. As a result, data samples will be provided
// to the registered sink.
// - At some point, a thread will call Stop(), which stops and joins the
// capture thread and at the same time stops audio streaming.
// - The same thread that called stop will call Close() where we cleanup
// and notify the audio manager, which likely will destroy this object.
// Implementation notes:
// - The minimum supported client is Windows Vista.
// - This implementation is single-threaded, hence:
// o Construction and destruction must take place from the same thread.
// o It is recommended to call all APIs from the same thread as well.
// - It is recommended to first acquire the native sample rate of the default
// input device and then use the same rate when creating this object. Use
// WASAPIAudioInputStream::HardwareSampleRate() to retrieve the sample rate.
// - Calling Close() also leads to self destruction.
// Core Audio API details:
// - Utilized MMDevice interfaces:
// o IMMDeviceEnumerator
// o IMMDevice
// - Utilized WASAPI interfaces:
// o IAudioClient
// o IAudioCaptureClient
// - The stream is initialized in shared mode and the processing of the
// audio buffer is event driven.
// - The Multimedia Class Scheduler service (MMCSS) is utilized to boost
// the priority of the capture thread.
// - Audio applications that use the MMDevice API and WASAPI typically use
// the ISimpleAudioVolume interface to manage stream volume levels on a
// per-session basis. It is also possible to use of the IAudioEndpointVolume
// interface to control the master volume level of an audio endpoint device.
// This implementation is using the ISimpleAudioVolume interface.
// MSDN states that "In rare cases, a specialized audio application might
// require the use of the IAudioEndpointVolume".
#include <Audioclient.h>
#include <MMDeviceAPI.h>
#include <endpointvolume.h>
#include <stddef.h>
#include <stdint.h>
#include <wrl/client.h>
#include <memory>
#include <string>
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/sequence_checker.h"
#include "base/threading/platform_thread.h"
#include "base/threading/simple_thread.h"
#include "base/win/scoped_co_mem.h"
#include "base/win/scoped_com_initializer.h"
#include "base/win/scoped_handle.h"
#include "media/audio/agc_audio_stream.h"
#include "media/audio/win/audio_manager_win.h"
#include "media/base/audio_converter.h"
#include "media/base/audio_parameters.h"
#include "media/base/media_export.h"
namespace media {
class AudioBlockFifo;
class AudioBus;
// AudioInputStream implementation using Windows Core Audio APIs.
class MEDIA_EXPORT WASAPIAudioInputStream
: public AgcAudioStream<AudioInputStream>,
public base::DelegateSimpleThread::Delegate,
public AudioConverter::InputCallback {
// The ctor takes all the usual parameters, plus |manager| which is the
// the audio manager who is creating this object.
WASAPIAudioInputStream(AudioManagerWin* manager,
const AudioParameters& params,
const std::string& device_id,
const AudioManager::LogCallback& log_callback);
// The dtor is typically called by the AudioManager only and it is usually
// triggered by calling AudioInputStream::Close().
~WASAPIAudioInputStream() override;
// Implementation of AudioInputStream.
bool Open() override;
void Start(AudioInputCallback* callback) override;
void Stop() override;
void Close() override;
double GetMaxVolume() override;
void SetVolume(double volume) override;
double GetVolume() override;
bool IsMuted() override;
void SetOutputDeviceForAec(const std::string& output_device_id) override;
bool started() const { return started_; }
// DelegateSimpleThread::Delegate implementation.
void Run() override;
// Pulls capture data from the endpoint device and pushes it to the sink.
void PullCaptureDataAndPushToSink();
// Issues the OnError() callback to the |sink_|.
void HandleError(HRESULT err);
// The Open() method is divided into these sub methods.
HRESULT SetCaptureDevice();
HRESULT GetAudioEngineStreamFormat();
// Returns whether the desired format is supported or not and writes the
// result of a failing system call to |*hr|, or S_OK if successful. If this
// function returns false with |*hr| == S_FALSE, the OS supports a closest
// match but we don't support conversion to it.
bool DesiredFormatIsSupported(HRESULT* hr);
void SetupConverterAndStoreFormatInfo();
HRESULT InitializeAudioEngine();
void ReportOpenResult(HRESULT hr) const;
// Reports stats for format related audio client initilization
// (IAudioClient::Initialize) errors, that is if |hr| is an error related to
// the format.
void MaybeReportFormatRelatedInitError(HRESULT hr) const;
// AudioConverter::InputCallback implementation.
double ProvideInput(AudioBus* audio_bus, uint32_t frames_delayed) override;
// Reports delay stats based on |capture_time|. Detects and counts glitches
// based on |frames_in_buffer|, |discontinuity_flagged|, and
// |device_position|.
void ReportDelayStatsAndUpdateGlitchCount(bool discontinuity_flagged,
UINT64 device_position,
base::TimeTicks capture_time);
// Reports glitch stats and resets associated variables.
void ReportAndResetGlitchStats();
// Used to track down where we fail during initialization which at the
// moment seems to be happening frequently and we're not sure why.
// The reason might be expected (e.g. trying to open "default" on a machine
// that has no audio devices).
// Note: This enum is used to record a histogram value and should not be
// re-ordered.
enum StreamOpenResult {
// Our creator, the audio manager needs to be notified when we close.
AudioManagerWin* const manager_;
// Capturing is driven by this thread (which has no message loop).
// All OnData() callbacks will be called from this thread.
std::unique_ptr<base::DelegateSimpleThread> capture_thread_;
// Contains the desired output audio format which is set up at construction
// and then never modified. It is the audio format this class will output
// data to the sink in, or equivalently, the format after the converter if
// such is needed. Does not need the extended version since we only support
// max stereo at this stage.
WAVEFORMATEX output_format_;
// Contains the audio format we get data from the audio engine in. Initially
// set to |output_format_| at construction but it might be changed to a close
// match if the audio engine doesn't support the originally set format. Note
// that, this is also the format after the FIFO, i.e. the input format to the
// converter if any.
bool opened_ = false;
bool started_ = false;
StreamOpenResult open_result_ = OPEN_RESULT_OK;
// Size in bytes of each audio frame before the converter (4 bytes for 16-bit
// stereo PCM). Note that this is the same before and after the fifo.
size_t frame_size_bytes_ = 0;
// Size in audio frames of each audio packet (buffer) after the fifo but
// before the converter.
size_t packet_size_frames_ = 0;
// Size in bytes of each audio packet (buffer) after the fifo but before the
// converter.
size_t packet_size_bytes_ = 0;
// Length of the audio endpoint buffer, i.e. the buffer size before the fifo.
uint32_t endpoint_buffer_size_frames_ = 0;
// Contains the unique name of the selected endpoint device.
// Note that AudioDeviceDescription::kDefaultDeviceId represents the default
// device role and is not a valid ID as such.
std::string device_id_;
// Pointer to the object that will receive the recorded audio samples.
AudioInputCallback* sink_ = nullptr;
// Windows Multimedia Device (MMDevice) API interfaces.
// An IMMDevice interface which represents an audio endpoint device.
Microsoft::WRL::ComPtr<IMMDevice> endpoint_device_;
// Windows Audio Session API (WASAPI) interfaces.
// An IAudioClient interface which enables a client to create and initialize
// an audio stream between an audio application and the audio engine.
Microsoft::WRL::ComPtr<IAudioClient> audio_client_;
// Loopback IAudioClient doesn't support event-driven mode, so a separate
// IAudioClient is needed to receive notifications when data is available in
// the buffer. For loopback input |audio_client_| is used to receive data,
// while |audio_render_client_for_loopback_| is used to get notifications
// when a new buffer is ready. See comment in InitializeAudioEngine() for
// details.
Microsoft::WRL::ComPtr<IAudioClient> audio_render_client_for_loopback_;
// The IAudioCaptureClient interface enables a client to read input data
// from a capture endpoint buffer.
Microsoft::WRL::ComPtr<IAudioCaptureClient> audio_capture_client_;
// The IAudioClock interface is used to get the current timestamp, as the
// timestamp from IAudioCaptureClient::GetBuffer can be unreliable with some
// devices.
Microsoft::WRL::ComPtr<IAudioClock> audio_clock_;
// The ISimpleAudioVolume interface enables a client to control the
// master volume level of an audio session.
// The volume-level is a value in the range 0.0 to 1.0.
// This interface does only work with shared-mode streams.
Microsoft::WRL::ComPtr<ISimpleAudioVolume> simple_audio_volume_;
// The IAudioEndpointVolume allows a client to control the volume level of
// the whole system.
Microsoft::WRL::ComPtr<IAudioEndpointVolume> system_audio_volume_;
// The audio engine will signal this event each time a buffer has been
// recorded.
base::win::ScopedHandle audio_samples_ready_event_;
// This event will be signaled when capturing shall stop.
base::win::ScopedHandle stop_capture_event_;
// Never set it through external API. Only used when |device_id_| ==
// kLoopbackWithMuteDeviceId.
// True, if we have muted the system audio for the stream capturing, and
// indicates that we need to unmute the system audio when stopping capturing.
bool mute_done_ = false;
// Used for the captured audio on the callback thread.
std::unique_ptr<AudioBlockFifo> fifo_;
// If the caller requires resampling (should only be in exceptional cases and
// ideally, never), we support using an AudioConverter.
std::unique_ptr<AudioConverter> converter_;
std::unique_ptr<AudioBus> convert_bus_;
bool imperfect_buffer_size_conversion_ = false;
// Callback to send log messages.
AudioManager::LogCallback log_callback_;
// For detecting and reporting glitches.
UINT64 expected_next_device_position_ = 0;
int total_glitches_ = 0;
int total_device_position_less_than_expected_ = 0;
int total_discontinuities_ = 0;
int total_concurrent_glitch_and_discontinuities_ = 0;
UINT64 total_lost_frames_ = 0;
UINT64 largest_glitch_frames_ = 0;
} // namespace media