Raspberry Pi 作为录音机 Win 10 iot答案

【问题标题】：Raspberry Pi as a Sound Recorder Win 10 iotRaspberry Pi 作为录音机 Win 10 iot
【发布时间】：2019-04-04 18:09:05
【问题描述】：

设备：树莓派 3 操作系统：WIN 10 物联网编程语言：C#

我正在尝试编写一个 24/7 全天候记录器，它会在 Raspberry 打开后立即记录所有内容。音频文件长度应在 30 分钟后。然后这些文件将按年、月、日存储在文件夹中的 U 盘上。 U 盘上的文件夹创建已经生效。

我遇到的问题是文件已创建但没有内容。该文件大小为 0kb。这是代码。

感谢您的帮助。

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Devices.Enumeration;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.Media.Capture;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using System.Collections.ObjectModel;
using System.Threading.Tasks;
using Windows.Media.MediaProperties;
using Windows.Media.Playback;
using Windows.Storage;
using Windows.Storage.Streams;

namespace Recording_PI
{
    /// <summary>
    /// Eine leere Seite, die eigenständig verwendet oder zu der innerhalb eines Rahmens navigiert werden kann.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        bool isRecording;
        LowLagMediaRecording audioRecording;
        MediaCapture audioCapture = new MediaCapture();

        public MainPage()
        {
            this.InitializeComponent();

            Checked();
            Task.Delay(10000).Wait();    
            Unchecked();


        }

        private async void Checked()
        {
            var settings = new Windows.Media.Capture.MediaCaptureInitializationSettings();
            settings.StreamingCaptureMode = Windows.Media.Capture.StreamingCaptureMode.Audio;
            settings.MediaCategory = Windows.Media.Capture.MediaCategory.Other;
            settings.AudioProcessing = Windows.Media.AudioProcessing.Default;
            await audioCapture.InitializeAsync(settings);

            StorageFolder externalDevices = KnownFolders.RemovableDevices;
            IReadOnlyList<StorageFolder> externalDrives = await externalDevices.GetFoldersAsync();
            StorageFolder usbStorage = externalDrives[0];

            //ENSURE FOLDER EXISTS
            if (await usbStorage.TryGetItemAsync("Recording") == null)
                await usbStorage.CreateFolderAsync("Recording");

            string Folder_Pfad = "Recording\\" + DateTime.Now.Year.ToString();
            if (await usbStorage.TryGetItemAsync(Folder_Pfad) == null)
                await usbStorage.CreateFolderAsync(Folder_Pfad);

            Folder_Pfad = Folder_Pfad + "\\" + DateTime.Now.Month.ToString();
            if (await usbStorage.TryGetItemAsync(Folder_Pfad) == null)
                await usbStorage.CreateFolderAsync(Folder_Pfad);

            Folder_Pfad = Folder_Pfad + "\\" + DateTime.Now.Day.ToString();
            if (await usbStorage.TryGetItemAsync(Folder_Pfad) == null)
                await usbStorage.CreateFolderAsync(Folder_Pfad);

            string Dateiname = "\\" + DateTime.Now.Year.ToString() + "-" + DateTime.Now.Month.ToString() + "-" + DateTime.Now.Day.ToString() + " "
                 + DateTime.Now.Hour.ToString() + "_" + DateTime.Now.Minute.ToString() + "_" + DateTime.Now.Second.ToString()+ ".mp3";

            string Dateispeicher_Ort = Folder_Pfad + Dateiname;

            StorageFile recordFile = await usbStorage.CreateFileAsync(Dateispeicher_Ort, Windows.Storage.CreationCollisionOption.GenerateUniqueName);

            await audioCapture.StartRecordToStorageFileAsync(MediaEncodingProfile.CreateMp3(AudioEncodingQuality.Medium), recordFile);

        }


        private async void Unchecked()
        {
            if (isRecording)
            {
                await audioCapture.StopRecordAsync();
            }

        }

    }
}

【问题讨论】：

标签： c# raspberry-pi3 windows-10-iot-core

【解决方案1】：

我遇到的问题是文件已创建但没有内容。这文件大小为 0kb。

这是因为您的代码在使用 Windows IoT Core 的 Raspberry Pi 上运行时在下一行出现异常，因此该文件尚未写入内容。如果您调试应用程序，您将因此异常而终止。

await audioCapture.StartRecordToStorageFileAsync(MediaEncodingProfile.CreateMp3(AudioEncodingQuality.Auto), recordFile);

您需要使用以下行而不是上面的行：

            var audioRecording = await audioCapture.PrepareLowLagRecordToStorageFileAsync(MediaEncodingProfile.CreateM4a(AudioEncodingQuality.Auto), recordFile);
            await audioRecording.StartAsync();

参考：“MediaCapture.PrepareLowLagRecordToStorageFileAsync”

您的代码中还有其他问题。

isRecording 变量从未启动或分配任何值，因此它始终为false。所以这条线永远不会被执行：await audioCapture.StopRecordAsync();
Unchecked()方法可能在Checked()函数完成之前执行，因为在Checked()方法中你使用await，所以代码会继续执行，然后是Task.Delay(10000).Wait();和Unchecked();。在这种情况下，音频将在开始之前停止。

另一个建议是在您的代码中添加 try-catch，以便您可以在应用终止之前处理异常。

基于以上所有，我对您的代码进行了一些编辑。下面是完整的代码，你可以试试看是否有帮助。

MainPage.xaml：

<Page
    x:Class="Recording_PI.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:Recording_PI"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <StackPanel VerticalAlignment="Center">
        <TextBlock Name="Result" Text="" />
    </StackPanel>
</Page>

MainPage.xaml.cs：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using Windows.Devices.Enumeration;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.Media.Capture;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using System.Collections.ObjectModel;
using System.Threading.Tasks;
using Windows.Media.MediaProperties;
using Windows.Media.Playback;
using Windows.Storage;
using Windows.Storage.Streams;
using Windows.ApplicationModel.Core;
using Windows.UI.Core;

namespace Recording_PI
{
    /// <summary>
    /// Eine leere Seite, die eigenständig verwendet oder zu der innerhalb eines Rahmens navigiert werden kann.
    /// </summary>
    public sealed partial class MainPage : Page
    {
        bool isRecording;
        LowLagMediaRecording audioRecording;
        MediaCapture audioCapture = new MediaCapture();

        public MainPage()
        {
            this.InitializeComponent();

            Checked();


        }

        private async void Checked()
        {
            try
            {
                var settings = new Windows.Media.Capture.MediaCaptureInitializationSettings();
                settings.StreamingCaptureMode = Windows.Media.Capture.StreamingCaptureMode.Audio;
                settings.MediaCategory = Windows.Media.Capture.MediaCategory.Other;
                settings.AudioProcessing = Windows.Media.AudioProcessing.Default;
                await audioCapture.InitializeAsync(settings);

                StorageFolder externalDevices = KnownFolders.RemovableDevices;
                IReadOnlyList<StorageFolder> externalDrives = await externalDevices.GetFoldersAsync();
                StorageFolder usbStorage = externalDrives[0];

                //ENSURE FOLDER EXISTS
                if (await usbStorage.TryGetItemAsync("Recording") == null)
                    await usbStorage.CreateFolderAsync("Recording");

                string Folder_Pfad = "Recording\\" + DateTime.Now.Year.ToString();
                if (await usbStorage.TryGetItemAsync(Folder_Pfad) == null)
                    await usbStorage.CreateFolderAsync(Folder_Pfad);

                Folder_Pfad = Folder_Pfad + "\\" + DateTime.Now.Month.ToString();
                if (await usbStorage.TryGetItemAsync(Folder_Pfad) == null)
                    await usbStorage.CreateFolderAsync(Folder_Pfad);

                Folder_Pfad = Folder_Pfad + "\\" + DateTime.Now.Day.ToString();
                if (await usbStorage.TryGetItemAsync(Folder_Pfad) == null)
                    await usbStorage.CreateFolderAsync(Folder_Pfad);

                string Dateiname = "\\" + DateTime.Now.Year.ToString() + "-" + DateTime.Now.Month.ToString() + "-" + DateTime.Now.Day.ToString() + " "
                     + DateTime.Now.Hour.ToString() + "_" + DateTime.Now.Minute.ToString() + "_" + DateTime.Now.Second.ToString() + ".mp3";

                string Dateispeicher_Ort = Folder_Pfad + Dateiname;

                StorageFile recordFile = await usbStorage.CreateFileAsync(Dateispeicher_Ort, Windows.Storage.CreationCollisionOption.GenerateUniqueName);

                isRecording = true;
                //await audioCapture.StartRecordToStorageFileAsync(MediaEncodingProfile.CreateMp3(AudioEncodingQuality.Auto), recordFile);

                var audioRecording = await audioCapture.PrepareLowLagRecordToStorageFileAsync(MediaEncodingProfile.CreateM4a(AudioEncodingQuality.Medium), recordFile);
                await audioRecording.StartAsync();

                Task.Delay(10000).Wait();
                Unchecked();
            }
            catch (Exception ex)
            {
                await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal, ()=> {
                    Result.Text += ex.Message;
                });

            }

        }


        private async void Unchecked()
        {
            if (isRecording)
            {
                await audioCapture.StopRecordAsync();
            }

        }

    }
}

package.appxmanifest 中的功能：

  <Capabilities>
    <uap:Capability Name="removableStorage" />
    <DeviceCapability Name="microphone" />
  </Capabilities>

【讨论】：

感谢您的帮助。现在效果很好。我是编程新手，所以代码来自不同的来源。