从Windows 8应用程序中生成的缓冲区播放声音

Question

我正在将一些C#Windows Phone 7应用移植到Windows 8.

手机应用程序使用XNA SoundEffect从缓冲区播放任意声音.在最简单的情况下,我只需要创建所需持续时间和频率的正弦波.持续时间和频率都可以变化很大,所以我宁愿不依赖MediaElements(除非有一些方法可以改变基本文件的频率,但这只会帮助我生成单频率).

WinRT中的XNA SoundEffectInstance相当于什么？

我假设我需要使用DirectX,但我不知道如何从其他C#/ XAML应用程序中解决这个问题.我已经看过SharpDX,但它似乎没有我认为我需要使用的DirectSound,SecondaryBuffer,SecondaryBuffer类.

我已经做了一些上面的假设.可能是我正在寻找错误的类,或者有一种完全独立的方式从Windows 8应用程序生成任意声音.

---

我找到了一个使用SharpDX的XAudio2通过AudioBuffer播放wav文件的例子.这似乎很有希望,我只需要将生成的音频缓冲区替换为本机文件流.

PM>安装包装SharpDX

PM> Install-Package SharpDX.XAudio2

    public void PlaySound()
    {
        XAudio2 xaudio;
        MasteringVoice masteringVoice;

        xaudio = new XAudio2();
        masteringVoice = new MasteringVoice(xaudio);

        var nativefilestream = new NativeFileStream(
            @"Assets\SpeechOn.wav",
            NativeFileMode.Open,
            NativeFileAccess.Read,
            NativeFileShare.Read);

        var soundstream = new SoundStream(nativefilestream);


        var waveFormat = soundstream.Format;
        var buffer = new AudioBuffer
        {
            Stream = soundstream.ToDataStream(),
            AudioBytes = (int)soundstream.Length,
            Flags = BufferFlags.EndOfStream
        };

        var sourceVoice = new SourceVoice(xaudio, waveFormat, true);

        // There is also support for shifting the frequency.
        sourceVoice.SetFrequencyRatio(0.5f);

        sourceVoice.SubmitSourceBuffer(buffer, soundstream.DecodedPacketsInfo);

        sourceVoice.Start();
    }

Answer 1

在Win8RT中生成动态声音的唯一方法是使用XAudio2,因此您应该能够使用SharpDX.XAudio2执行此操作.

而不是使用NativeFileStream,只需实例化一个直接给出托管缓冲区的DataStream(或者您可以使用非托管缓冲区或让DataStream为您实例化一个).代码如下:

// Initialization phase, keep this buffer during the life of your application
// Allocate 10s at 44.1Khz of stereo 16bit signals
var myBufferOfSamples = new short[44100 * 10 * 2];

// Create a DataStream with pinned managed buffer
var dataStream = DataStream.Create(myBufferOfSamples, true, true);

var buffer = new AudioBuffer
        {
            Stream = dataStream,
            AudioBytes = (int)dataStream.Length,
            Flags = BufferFlags.EndOfStream
        };

//...
// Fill myBufferOfSamples
//...

// PCM 44.1Khz stereo 16 bit format
var waveFormat = new WaveFormat();

XAudio2 xaudio = new XAudio2();
MasteringVoice masteringVoice = new MasteringVoice(xaudio);
var sourceVoice = new SourceVoice(xaudio, waveFormat, true);

// Submit the buffer
sourceVoice.SubmitSourceBuffer(buffer, null);

// Start playing
sourceVoice.Start();

使用正弦波填充缓冲区的示例方法:

    private void FillBuffer(short[] buffer, int sampleRate, double frequency)
    {
        double totalTime = 0;

        for (int i = 0; i < buffer.Length - 1; i += 2)
        {
            double time = (double)totalTime / (double)sampleRate;
            short currentSample = (short)(Math.Sin(2 * Math.PI * frequency * time) * (double)short.MaxValue);

            buffer[i] = currentSample; //(short)(currentSample & 0xFF);
            buffer[i + 1] = currentSample; //(short)(currentSample >> 8);

            totalTime += 2;
        }

    }