我正在App.xaml.cs中设置一个AudioGraph，因为如果我尝试在MainPage上执行该操作，则该应用程序会挂起，永远不会返回AudioGraph。
然后，我要设置一个可变频率，该频率将由MainPage.xaml.cs上的滑块控制。
然后，当按下键“ a”时，将通过音频图表播放频率。
要使其正常工作，我需要在MainPage.xaml.cs上启动AudioGraph。
如何获取只能从App.xaml.cs获得的AudioGraph并将其放入MainPage.xaml.cs的AudioGraph对象中？
我尝试在MainPage.xaml.cs上初始化AudioGraph，但它永远不会返回并挂起。
我尝试在App.xaml.cs上设置可变频率，但是因为该类是密封的，所以不能。
实际上，这两个类都是密封的，因此我不确定如何使两者相互通信。即使我将它们公开，也不会起作用。
这是MainPage.xaml.cs
namespace FG
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page
{
// For audio nodes through which audio data flows
AudioGraph audioGraph;
// Pushes audio data that is generated
AudioFrameInputNode frameInputNode;
double pitch = 1000; // choosing to generate frequency of 1kHz
public MainPage()
{
this.InitializeComponent();
this.Focus(FocusState.Keyboard);
}
public void setAudioGraph(AudioGraph ag)
{
audioGraph = ag;
}
public void setFrameInputNode(AudioFrameInputNode fin)
{
frameInputNode = fin;
}
private void Slider_ValueChanged(object sender, RangeBaseValueChangedEventArgs e)
{
Slider slider = sender as Slider;
if (slider != null)
{
pitch = slider.Value;
}
}
private void Key_Down(object sender, KeyRoutedEventArgs e)
{
if (e.Key == VirtualKey.A)
{
frameInputNode.Start();
audioGraph.Start();
}
}
private void Key_Up(object sender, KeyRoutedEventArgs e)
{
frameInputNode.Stop();
audioGraph.Stop();
}
}
}
这是App.xaml.cs
namespace FG
{
/// <summary>
/// Provides application-specific behavior to supplement the default Application class.
/// </summary>
sealed partial class App : Application
{
// For audio out
AudioDeviceOutputNode deviceOutputNode;
// Access to the underlying memory buffer
[ComImport]
[Guid("5B0D3235-4DBA-4D44-865E-8F1D0E4FD04D")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
unsafe interface IMemoryBufferByteAccess
{
void GetBuffer(out byte* buffer, out uint capacity);
}
/// <summary>
/// Initializes the singleton application object. This is the first line of authored code
/// executed, and as such is the logical equivalent of main() or WinMain().
/// </summary>
public App()
{
this.InitializeComponent();
// Setup audio pipeline
InitAudioGraph().Wait();
CreateDeviceOutputNode().Wait();
CreateFrameInputNode();
frameInputNode.AddOutgoingConnection(deviceOutputNode);
this.Suspending += OnSuspending;
}
public async Task InitAudioGraph()
{
AudioGraphSettings settings = new AudioGraphSettings(Windows.Media.Render.AudioRenderCategory.Media);
CreateAudioGraphResult result = await AudioGraph.CreateAsync(settings);
audioGraph = result.Graph;
}
private async Task CreateDeviceOutputNode()
{
// Create a device output node
CreateAudioDeviceOutputNodeResult result = await audioGraph.CreateDeviceOutputNodeAsync();
deviceOutputNode = result.DeviceOutputNode;
}
private void CreateFrameInputNode()
{
// Create the FrameInputNode at the same format as the graph, except explicitly set mono.
AudioEncodingProperties nodeEncodingProperties = audioGraph.EncodingProperties;
nodeEncodingProperties.ChannelCount = 1;
frameInputNode = audioGraph.CreateFrameInputNode(nodeEncodingProperties);
// Initialize the Frame Input Node in the stopped state
frameInputNode.Stop();
// Hook up an event handler so we can start generating samples when needed
// This event is triggered when the node is required to provide data
frameInputNode.QuantumStarted += node_QuantumStarted;
}
private void node_QuantumStarted(AudioFrameInputNode sender, FrameInputNodeQuantumStartedEventArgs args)
{
// GenerateAudioData can provide PCM audio data by directly synthesizing it or reading from a file.
// Need to know how many samples are required. In this case, the node is running at the same rate as the rest of the graph
// For minimum latency, only provide the required amount of samples. Extra samples will introduce additional latency.
uint numSamplesNeeded = (uint)args.RequiredSamples;
if (numSamplesNeeded != 0)
{
AudioFrame audioData = GenerateAudioData(numSamplesNeeded);
frameInputNode.AddFrame(audioData);
}
}
unsafe private AudioFrame GenerateAudioData(uint samples)
{
double audioWaveTheta = 0;
// Buffer size is (number of samples) * (size of each sample)
// We choose to generate single channel (mono) audio. For multi-channel, multiply by number of channels
uint bufferSize = samples * sizeof(float);
AudioFrame frame = new Windows.Media.AudioFrame(bufferSize);
using (AudioBuffer buffer = frame.LockBuffer(AudioBufferAccessMode.Write))
using (IMemoryBufferReference reference = buffer.CreateReference())
{
byte* dataInBytes;
uint capacityInBytes;
float* dataInFloat;
// Get the buffer from the AudioFrame
((IMemoryBufferByteAccess)reference).GetBuffer(out dataInBytes, out capacityInBytes);
// Cast to float since the data we are generating is float
dataInFloat = (float*)dataInBytes;
float amplitude = 0.3f;
int sampleRate = (int)audioGraph.EncodingProperties.SampleRate;
double sampleIncrement = (pitch * (Math.PI * 2)) / sampleRate;
// Generate a 1kHz sine wave and populate the values in the memory buffer
for (int i = 0; i < samples; i++)
{
double sinValue = amplitude * Math.Sin(audioWaveTheta);
dataInFloat[i] = (float)sinValue;
audioWaveTheta += sampleIncrement;
}
}
return frame;
}
}
I expect to be able to initialize an AudioGraph (only works in App.xaml.cs) and use it to play a frequency that is set with a slider on the MainPage and triggered with a keydown event on the MainPage.
答案 0 :(得分：0)
我可以使用以下代码
```
// For generating frequencies
namespace FG
{
/// <summary>
/// Provides application-specific behavior to supplement the default Application class.
/// </summary>
sealed partial class App : Application
{
// For audio nodes through which audio data flows
static AudioGraph audioGraph;
// Pushes audio data that is generated
static AudioFrameInputNode frameInputNode;
// Pitch in hz
static float pitch = 1000;
// For audio out
AudioDeviceOutputNode deviceOutputNode;
// Access to the underlying memory buffer
[ComImport]
[Guid("5B0D3235-4DBA-4D44-865E-8F1D0E4FD04D")]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
unsafe interface IMemoryBufferByteAccess
{
void GetBuffer(out byte* buffer, out uint capacity);
}
/// <summary>
/// Initializes the singleton application object. This is the first line of authored code
/// executed, and as such is the logical equivalent of main() or WinMain().
/// </summary>
public App()
{
this.InitializeComponent();
// Setup audio pipeline
InitAudioGraph().Wait();
// For audio playback
CreateDeviceOutputNode().Wait();
// of audio frames
CreateFrameInputNode();
frameInputNode.AddOutgoingConnection(deviceOutputNode);
this.Suspending += OnSuspending;
}
// Initializes AudioGraph
public async Task InitAudioGraph()
{
AudioGraphSettings settings = new AudioGraphSettings(AudioRenderCategory.Media);
CreateAudioGraphResult result = await
AudioGraph.CreateAsync(settings);
audioGraph = result.Graph;
}
// Creates an AudioDeviceOutputNode for sending audio to playback device
private async Task CreateDeviceOutputNode()
{
// Create a device output node
CreateAudioDeviceOutputNodeResult result = await audioGraph.CreateDeviceOutputNodeAsync();
deviceOutputNode = result.DeviceOutputNode;
}
// Creates FrameInputNode for taking in audio frames
private void CreateFrameInputNode()
{
// Create the FrameInputNode at the same format as the graph, except explicitly set mono.
AudioEncodingProperties nodeEncodingProperties = audioGraph.EncodingProperties;
frameInputNode = audioGraph.CreateFrameInputNode(nodeEncodingProperties);
// Initialize the Frame Input Node in the stopped state
frameInputNode.Stop();
// Hook up an event handler so we can start generating samples when needed
// This event is triggered when the node is required to provide data
frameInputNode.QuantumStarted += node_QuantumStarted;
}
// For creating audio frames on the fly
private void node_QuantumStarted(AudioFrameInputNode sender, FrameInputNodeQuantumStartedEventArgs args)
{
// GenerateAudioData can provide PCM audio data by directly synthesizing it or reading from a file.
// Need to know how many samples are required. In this case, the node is running at the same rate as the rest of the graph
// For minimum latency, only provide the required amount of samples. Extra samples will introduce additional latency.
uint numSamplesNeeded = (uint)args.RequiredSamples;
if (numSamplesNeeded != 0)
{
AudioFrame audioData = GenerateAudioData(numSamplesNeeded);
frameInputNode.AddFrame(audioData);
}
}
// Generate audioframes for the audiograph
unsafe private AudioFrame GenerateAudioData(uint samples)
{
// Buffer size is (number of samples) * (size of each sample)
// We choose to generate single channel (mono) audio. For multi-channel, multiply by number of channels
uint bufferSize = samples * frameInputNode.EncodingProperties.BitsPerSample;
AudioFrame frame = new Windows.Media.AudioFrame(bufferSize);
using (AudioBuffer buffer = frame.LockBuffer(AudioBufferAccessMode.Write))
using (IMemoryBufferReference reference = buffer.CreateReference())
{
byte* dataInBytes;
uint capacityInBytes;
float* dataInFloat;
// Get the buffer from the AudioFrame
((IMemoryBufferByteAccess)reference).GetBuffer(out dataInBytes, out capacityInBytes);
// Cast to float since the data we are generating is float
dataInFloat = (float*)dataInBytes;
float amplitude = 0.3f;
int sampleRate = (int)audioGraph.EncodingProperties.SampleRate;
double sampleIncrement = ((pitch*2*Math.PI)/sampleRate);
// Generate a 1kHz sine wave and populate the values in the memory buffer
for (int i = 0; i < samples; i++)
{
double sinValue = amplitude * Math.Sin(i*sampleIncrement);
dataInFloat[i] = (float)sinValue;
}
}
return frame;
}
/// <summary>
/// Invoked when the application is launched normally by the end user. Other entry points
/// will be used such as when the application is launched to open a specific file.
/// </summary>
/// <param name="e">Details about the launch request and process.</param>
protected override void OnLaunched(LaunchActivatedEventArgs e)
{
Frame rootFrame = Window.Current.Content as Frame;
// Do not repeat app initialization when the Window already has content,
// just ensure that the window is active
if (rootFrame == null)
{
// Create a Frame to act as the navigation context and navigate to the first page
rootFrame = new Frame();
rootFrame.NavigationFailed += OnNavigationFailed;
if (e.PreviousExecutionState == ApplicationExecutionState.Terminated)
{
//TODO: Load state from previously suspended application
}
// Place the frame in the current Window
Window.Current.Content = rootFrame;
}
if (e.PrelaunchActivated == false)
{
if (rootFrame.Content == null)
{
// When the navigation stack isn't restored navigate to the first page,
// configuring the new page by passing required information as a navigation
// parameter
rootFrame.Navigate(typeof(MainPage), e.Arguments);
}
// Ensure the current window is active
Window.Current.Activate();
}
}
/// <summary>
/// Invoked when Navigation to a certain page fails
/// </summary>
/// <param name="sender">The Frame which failed navigation</param>
/// <param name="e">Details about the navigation failure</param>
void OnNavigationFailed(object sender, NavigationFailedEventArgs e)
{
throw new Exception("Failed to load Page " + e.SourcePageType.FullName);
}
/// <summary>
/// Invoked when application execution is being suspended. Application state is saved
/// without knowing whether the application will be terminated or resumed with the contents
/// of memory still intact.
/// </summary>
/// <param name="sender">The source of the suspend request.</param>
/// <param name="e">Details about the suspend request.</param>
private void OnSuspending(object sender, SuspendingEventArgs e)
{
var deferral = e.SuspendingOperation.GetDeferral();
//TODO: Save application state and stop any background activity
deferral.Complete();
}
internal static void setPitch(float value)
{
pitch = value;
}
internal static void StartNoise()
{
frameInputNode.Start();
audioGraph.Start();
}
internal static void StopNoise()
{
frameInputNode.Stop();
audioGraph.Stop();
}
}
}
```
namespace FG
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
Window.Current.CoreWindow.KeyDown += CoreWindow_KeyDown;
Window.Current.CoreWindow.KeyUp += CoreWindow_KeyUp;
}
void CoreWindow_KeyDown(Windows.UI.Core.CoreWindow sender, Windows.UI.Core.KeyEventArgs args)
{
if (args.VirtualKey == VirtualKey.A)
{
App.StartNoise();
}
}
void CoreWindow_KeyUp(Windows.UI.Core.CoreWindow sender, Windows.UI.Core.KeyEventArgs args)
{
if (args.VirtualKey == VirtualKey.A)
{
App.StopNoise();
}
}
private void PitchTextChanged(object sender, TextChangedEventArgs e)
{
try
{
App.setPitch(float.Parse(((TextBox)sender).Text));
}
catch(FormatException)
{
}
}
}
唯一的问题是频率输出错误...