Silverlight实用窍门系列:41.Silverlight中调用麦克风模拟录音机设备,存储为WAV音频【附带实例源码】

        在Silverlight 4中支持了麦克风设置的调用,在本节中我们将调用麦克风设备,然后进行录音,并且将录制的声音存取为Wav音频文件。

        第一步、首先我们从AudioSink类派生一个音频接收器类:WavAudioSink。其代码如下所示:

public class WavAudioSink:AudioSink
{
// 设置需要记录的内存流
private MemoryStream _stream;
// 设置当前的音频格式
private AudioFormat _format;

public Stream BackingStream
{
get { return _stream; }
}

public AudioFormat CurrentFormat
{
get { return _format; }
}

protected override void OnCaptureStarted()
{
_stream
= new MemoryStream(1024);
}

protected override void OnCaptureStopped()
{
}

protected override void OnFormatChange(AudioFormat audioFormat)
{
if (audioFormat.WaveFormat != WaveFormatType.Pcm)
throw new InvalidOperationException("WavAudioSink只支持PCM音频格式");

_format
= audioFormat;
}

protected override void OnSamples(long sampleTime, long sampleDuration,
byte[] sampleData)
{
// 新的音频数据到达,将它们写入流
_stream.Write(sampleData, 0, sampleData.Length);
}
}
        第二步、然后我们将编写一个保存音频的函数类,以保存读取到的音频数据:
public class SaveWAVHelper
{
public static void SavePcmToWav(Stream rawData, Stream output, AudioFormat audioFormat)
{
if (audioFormat.WaveFormat != WaveFormatType.Pcm)
throw new ArgumentException("Only PCM coding is supported.");

BinaryWriter bwOutput
= new BinaryWriter(output);

// -- RIFF 块
bwOutput.Write("RIFF".ToCharArray());
// 包的总长度
// 计算的数据长度加上数据头的长度没有数据
// 写数据(44 - 4 ("RIFF") - 4 (当前数据))
bwOutput.Write((uint)(rawData.Length + 36));
bwOutput.Write(
"WAVE".ToCharArray());

// -- FORMAT 块
bwOutput.Write("fmt ".ToCharArray());
// FORMAT 块的长度 (Binary, 总是 0x10)
bwOutput.Write((uint)0x10);
// 总是 0x01
bwOutput.Write((ushort)0x01);
// 通道数( 0x01=单声道, 0x02=立体声)
bwOutput.Write((ushort)audioFormat.Channels);
// 采样率 (Binary, Hz为单位)
bwOutput.Write((uint)audioFormat.SamplesPerSecond);
// 字节每秒
bwOutput.Write((uint)(audioFormat.BitsPerSample * audioFormat.SamplesPerSecond *
audioFormat.Channels
/ 8));
// 每个样品字节: 1=8 bit 单声道, 2=8 bit 立体声 or 16 bit 单声道, 4=16 bit 立体声
bwOutput.Write((ushort)(audioFormat.BitsPerSample * audioFormat.Channels / 8));
// 每个样品字节
bwOutput.Write((ushort)audioFormat.BitsPerSample);

// -- DATA 块
bwOutput.Write("data".ToCharArray());
// DATA数据块的长度
bwOutput.Write((uint)rawData.Length);
// 原始PCM数据如下
// 复位rawData地位,记住它的原点位置
// 恢复底。
long originalRawDataStreamPosition = rawData.Position;
rawData.Seek(
0, SeekOrigin.Begin);
//追加到输出流中的所有数据从rawData流
byte[] buffer = new byte[4096];
int read;
// 循环读取字节数据
while ((read = rawData.Read(buffer, 0, 4096)) > 0)
{
bwOutput.Write(buffer,
0, read);
}
//开始写入数据
rawData.Seek(originalRawDataStreamPosition, SeekOrigin.Begin);
}
}
        第三步、然后再MainPage.xaml中我们添加三个按钮,分别是开始记录音频、停止录制音频、保存音频文件三个按钮。
<Grid x:Name="LayoutRoot" Background="White">
<Button Content="开始录制" Height="28" HorizontalAlignment="Left"
Margin
="30,15,0,0" Name="btnRecord" VerticalAlignment="Top"
Width
="71" Click="btnRecord_Click" />
<Button Content="停止录制" Height="28" HorizontalAlignment="Left"
Margin
="150,15,0,0" Name="btnStopRecord" VerticalAlignment="Top"
Width
="71" Click="btnStopRecord_Click" />
<Button Content="保存音频" Height="28" HorizontalAlignment="Left"
Margin
="268,15,0,0" Name="btnSaveWav" VerticalAlignment="Top"
Width
="71" Click="btnSaveWav_Click" />
</Grid>
        第四步、最后在MainPage.xaml.cs代码中我们进行录制、停止、保存音频的操作如下所示:
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();

btnRecord.IsEnabled
= true;
btnStopRecord.IsEnabled
= false;
btnSaveWav.IsEnabled
= false;
}

//声明私有变量
private WavAudioSink _wavSink;
private CaptureSource _captureSource;
private SaveFileDialog _saveFileDialog = new SaveFileDialog()
{ Filter
= "Audio files (*.wav)|*.wav" };

private void btnRecord_Click(object sender, RoutedEventArgs e)
{

//初始化_captureSource
var audioDevice = CaptureDeviceConfiguration.GetDefaultAudioCaptureDevice();
_captureSource
= new CaptureSource() { AudioCaptureDevice = audioDevice };

//有默认设置的设备且可以用来录制音频
if (CaptureDeviceConfiguration.AllowedDeviceAccess ||
CaptureDeviceConfiguration.RequestDeviceAccess())
{
//判断当前没有开始录制音频
if (_captureSource.State == CaptureState.Stopped)
{
//初始化WavAudioSink
_wavSink = new WavAudioSink();
_wavSink.CaptureSource
= _captureSource;
//开始录制音频
_captureSource.Start();

}
}


btnRecord.IsEnabled
= false;
btnStopRecord.IsEnabled
= true;
btnSaveWav.IsEnabled
= false;
}

private void btnStopRecord_Click(object sender, RoutedEventArgs e)
{
//如果当前状态为开始录制,则停止录制
if (_captureSource.State == CaptureState.Started)
{
_captureSource.Stop();
}


btnRecord.IsEnabled
= false;
btnStopRecord.IsEnabled
= false;
btnSaveWav.IsEnabled
= true;
}

private void btnSaveWav_Click(object sender, RoutedEventArgs e)
{
if (_saveFileDialog.ShowDialog() == false)
{
return;
}
//保存Wav文件
Stream stream = _saveFileDialog.OpenFile();
SaveWAVHelper.SavePcmToWav(_wavSink.BackingStream, stream, _wavSink.CurrentFormat);

stream.Close();

MessageBox.Show(
"你的音频已经保存");


btnRecord.IsEnabled
= true;
btnStopRecord.IsEnabled
= false;
btnSaveWav.IsEnabled
= false;
}
}

        通过以上步骤我们就可以开始调用麦克风录制音频文件了,本实例采用Silverlight 4.0+VS2010编写,如需源码请点击 SL4Audio.zip 下载。其效果图如下所示:

posted @ 2011-05-16 11:09  程兴亮  阅读(2664)  评论(6编辑  收藏