Android.Media.AudioTrack.GetMinBufferSize方法-如何在Xamarin.Android（c＃）中使用其语法？

Question

I am currently making a music app for Android in Xamarin studio using csharp. I am making a simple synthesizer app and at the moment I am stuck with GetMinBufferSize method with csharp.

Xamarin.Android documentation provides the following syntax for the GetMinBufferSize method (here's the link: xamarin API audiotrack documentation :

[Android.Runtime.Register("getMinBufferSize", "(III)I", "")]
public static int GetMinBufferSize (int sampleRateInHz, 
[Android.Runtime.GeneratedEnum] ChannelOut channelConfig, 
[Android.Runtime.GeneratedEnum] Encoding audioFormat)

• which corresponds to the following in Java (link: android reference ):

public static int getMinBufferSize (int sampleRateInHz, int channelConfig, int audioFormat)

The thing I do not understand is what are theses things and how I should use them: [Android.Runtime.Register("getMinBufferSize", "(III)I", "")] [Android.Runtime.GeneratedEnum] [Android.Runtime.GeneratedEnum]

The code in Java was easier:

int buffsize = AudioTrack.getMinBufferSize(_sampleRate, 
AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT);

where _sampleRate is int _sampleRate = 44100; and represents frequency rate.

So, if you at least told me what those three lines in brackets from xamarin documentation are - I would be so grateful.

Thank you in advance and have a great day.

My code so far:

namespace simple_synth
{

[Activity (Label = "_secondAct")]   //activity that opens the second screen     
public class _secondAct : Activity
{

Thread _thread; //audio processing thread    
int _sRate = 44100; //sampling rate
bool isRunning = true;  //switch on/off

protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
SetContentView (Resource.Layout._secondLay);

Button btn2 = FindViewById<Button> (Resource.Id.myButton_synth);
_audio _audioSound = new _audio ();


btn2.Click += (sender, e) => {

btn2.Text = "GOOD";
Thread _audioThread = new Thread(_audioSound._makeSound);
_audioThread.Start(); 
Console.WriteLine("audio thread: started");
while (!_audioThread.IsAlive);
Thread.Sleep(1000);
_audioSound._stopRequest();
_audioThread.Join();
Console.WriteLine("audio thread: terminated now!");
_audioSound._startRequest();
};
}
}//_secondAct

public class _audio{

private volatile bool _stopItNow;

public void _makeSound(){   // This method will be called when the thread is started. 

while (!_stopItNow) {

Console.WriteLine ("audio thread: is playing the sound...");
AudioTrack _audioTrack = new AudioTrack (Stream.Music, 22050, 
ChannelConfiguration.Mono, 
Android.Media.Encoding.Pcm16bit, 
_audBuffer.Length, AudioTrackMode.Stream);

_audioTrack.Play ();
_audioTrack.Write (_audBuffer, 0, _audBuffer.Length);
}

Console.WriteLine ("audio thread: terminated.");

} //doWork

public void _stopRequest()
{
_stopItNow = true;
}

public void _startRequest()
{
_stopItNow = false;
}
}
}

Answer 1

Very simple in C# as well:

var minBufSize = AudioTrack.GetMinBufferSize (
    44100, 
    ChannelOut.Mono, 
    Encoding.Pcm16bit);