同时录制音频和播放声音 - C# - Windows Phone 8.1

Question

我正在尝试录制音频并直接播放（我想在耳机中听到我的声音而不保存它）但是 MediaElement 和 MediaCapture 似乎不能同时工作。 我初始化了我的 MediaCapture：

    _mediaCaptureManager = new MediaCapture();
    var settings = new MediaCaptureInitializationSettings();
    settings.StreamingCaptureMode = StreamingCaptureMode.Audio;
    settings.MediaCategory = MediaCategory.Other;
    settings.AudioProcessing = AudioProcessing.Default;
    await _mediaCaptureManager.InitializeAsync(settings);

但是我真的不知道如何进行；我想知道其中一种方法是否可行（我尝试实施它们但没有成功，我还没有找到示例）：

1. 有没有办法使用 StartPreviewAsync() 录制音频，或者它只适用于视频？我注意到在设置 CaptureElement Source 时出现以下错误：“指定的对象或值不存在”；只有当我写“settings.StreamingCaptureMode = StreamingCaptureMode.Audio;”时才会发生虽然一切都适用于 .Video。
2. 如何使用 StartRecordToStreamAsync() 录制到流中；我的意思是，我该如何初始化 IRandomAccessStream 并从中读取？我可以写流，同时继续读吗？

3. 我读到将 MediaElement 的 AudioCathegory 和 MediaCapture 的 MediaCathegory 更改为 Communication 有可能它可以工作。然而，虽然我的代码在以前的设置下工作（它只需要记录并保存在一个文件中），但如果我写了“settings.MediaCategory = MediaCategory.Communication;”，它就不起作用了。而不是“settings.MediaCategory = MediaCategory.Other;”。你能告诉我为什么吗？ 这是我目前的程序，只是记录、保存和播放：

   private async void CaptureAudio()
   {
       try
       {
          _recordStorageFile = await KnownFolders.VideosLibrary.CreateFileAsync(fileName, CreationCollisionOption.GenerateUniqueName);                      
         MediaEncodingProfile recordProfile = MediaEncodingProfile.CreateWav(AudioEncodingQuality.Auto);
         await _mediaCaptureManager.StartRecordToStorageFileAsync(recordProfile, this._recordStorageFile);
         _recording = true;
        }
        catch (Exception e)
        {
           Debug.WriteLine("Failed to capture audio:"+e.Message);
        }
   }
   
   private async void StopCapture()
   {
      if (_recording)
      {
         await _mediaCaptureManager.StopRecordAsync();
         _recording = false;
      }
   }
   
   private async void PlayRecordedCapture()
   {
      if (!_recording)
      {
         var stream = await   _recordStorageFile.OpenAsync(FileAccessMode.Read);
         playbackElement1.AutoPlay = true;
         playbackElement1.SetSource(stream, _recordStorageFile.FileType);
         playbackElement1.Play();
      }
   }
   

如果您有任何建议，我将不胜感激。 祝你有美好的一天。

Answer 1

您会考虑改为以 Windows 10 为目标吗？新的 AudioGraph API 允许您做到这一点，Scenario 2 (Device Capture) in the SDK sample 很好地展示了这一点。

首先，该示例将所有输出设备填充到一个列表中：

private async Task PopulateDeviceList()
{
    outputDevicesListBox.Items.Clear();
    outputDevices = await DeviceInformation.FindAllAsync(MediaDevice.GetAudioRenderSelector());
    outputDevicesListBox.Items.Add("-- Pick output device --");
    foreach (var device in outputDevices)
    {
        outputDevicesListBox.Items.Add(device.Name);
    }
}

然后开始构建 AudioGraph：

AudioGraphSettings settings = new AudioGraphSettings(AudioRenderCategory.Media);
settings.QuantumSizeSelectionMode = QuantumSizeSelectionMode.LowestLatency;

// Use the selected device from the outputDevicesListBox to preview the recording
settings.PrimaryRenderDevice = outputDevices[outputDevicesListBox.SelectedIndex - 1];

CreateAudioGraphResult result = await AudioGraph.CreateAsync(settings);

if (result.Status != AudioGraphCreationStatus.Success)
{
    // TODO: Cannot create graph, propagate error message
    return;
}

AudioGraph graph = result.Graph;

// Create a device output node
CreateAudioDeviceOutputNodeResult deviceOutputNodeResult = await graph.CreateDeviceOutputNodeAsync();
if (deviceOutputNodeResult.Status != AudioDeviceNodeCreationStatus.Success)
{
    // TODO: Cannot create device output node, propagate error message
    return;
}

deviceOutputNode = deviceOutputNodeResult.DeviceOutputNode;

// Create a device input node using the default audio input device
CreateAudioDeviceInputNodeResult deviceInputNodeResult = await graph.CreateDeviceInputNodeAsync(MediaCategory.Other);

if (deviceInputNodeResult.Status != AudioDeviceNodeCreationStatus.Success)
{
    // TODO: Cannot create device input node, propagate error message
    return;
}

deviceInputNode = deviceInputNodeResult.DeviceInputNode;

// Because we are using lowest latency setting, we need to handle device disconnection errors
graph.UnrecoverableErrorOccurred += Graph_UnrecoverableErrorOccurred;

// Start setting up the output file
FileSavePicker saveFilePicker = new FileSavePicker();
saveFilePicker.FileTypeChoices.Add("Pulse Code Modulation", new List<string>() { ".wav" });
saveFilePicker.FileTypeChoices.Add("Windows Media Audio", new List<string>() { ".wma" });
saveFilePicker.FileTypeChoices.Add("MPEG Audio Layer-3", new List<string>() { ".mp3" });
saveFilePicker.SuggestedFileName = "New Audio Track";
StorageFile file = await saveFilePicker.PickSaveFileAsync();

// File can be null if cancel is hit in the file picker
if (file == null)
{
    return;
}

MediaEncodingProfile fileProfile = CreateMediaEncodingProfile(file);

// Operate node at the graph format, but save file at the specified format
CreateAudioFileOutputNodeResult fileOutputNodeResult = await graph.CreateFileOutputNodeAsync(file, fileProfile);

if (fileOutputNodeResult.Status != AudioFileNodeCreationStatus.Success)
{
    // TODO: FileOutputNode creation failed, propagate error message
    return;
}

fileOutputNode = fileOutputNodeResult.FileOutputNode;

// Connect the input node to both output nodes
deviceInputNode.AddOutgoingConnection(fileOutputNode);
deviceInputNode.AddOutgoingConnection(deviceOutputNode);

所有这些都完成后，您可以在录制到文件的同时播放录制的音频，如下所示：

private async Task ToggleRecordStop()
{
    if (recordStopButton.Content.Equals("Record"))
    {
        graph.Start();
        recordStopButton.Content = "Stop";
    }
    else if (recordStopButton.Content.Equals("Stop"))
    {
        // Good idea to stop the graph to avoid data loss
        graph.Stop();
        TranscodeFailureReason finalizeResult = await fileOutputNode.FinalizeAsync();
        if (finalizeResult != TranscodeFailureReason.None)
        {
            // TODO: Finalization of file failed. Check result code to see why, propagate error message
            return;
        }

        recordStopButton.Content = "Record";
    }
}