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[hmassad]

[SlimDX] DirectSound: Capture Microphone Stream With Low Latency Example

using System;
using SlimDX;
using SlimDX.DirectSound;
using SlimDX.Multimedia;
using System.IO;
using System.Threading;
using System.Collections.Generic;

namespace CaptureSound
{
    class Program
    {
        [System.Runtime.InteropServices.DllImport("user32.dll", CharSet = System.Runtime.InteropServices.CharSet.Auto)]
        static extern short GetAsyncKeyState(int key);
        const int VK_ESCAPE = 0x1B;

        static void Main(string[] args)
        {
            WaveFormat format = new WaveFormat();
            format.FormatTag = WaveFormatTag.Pcm;
            format.Channels = 1;
            format.BitsPerSample = 16;
            format.SamplesPerSecond = 8000;
            format.BlockAlignment = (short)(format.BitsPerSample / 8);
            format.AverageBytesPerSecond = format.SamplesPerSecond * format.BlockAlignment * format.Channels;

            FileStream stream = File.Open("output.raw", FileMode.OpenOrCreate);

            SoundBufferDescription primaryBufferDescription = new SoundBufferDescription();
            primaryBufferDescription.Format = format;
            primaryBufferDescription.Flags = BufferFlags.GlobalFocus;
            primaryBufferDescription.SizeInBytes = 2 * format.AverageBytesPerSecond;

            // Primary Buffer
            DirectSound ds = new DirectSound();
            ds.SetCooperativeLevel(System.Diagnostics.Process.GetCurrentProcess().MainWindowHandle, CooperativeLevel.Normal);

            // Capture
            CaptureBufferDescription captureBufferDescription = new CaptureBufferDescription()
            {
                Format = format,
                BufferBytes = format.AverageBytesPerSecond / 50, // 20ms
                WaveMapped = true,
                ControlEffects = false,
            };
            DirectSoundCapture directSoundCapture = new DirectSoundCapture();
            CaptureBuffer captureBuffer = new CaptureBuffer(directSoundCapture, captureBufferDescription);

            const int bufferPortionCount = 2;
            int bufferPortionSize = captureBuffer.SizeInBytes / bufferPortionCount;

            List<NotificationPosition> notifications = new List<NotificationPosition>();
            for (int i = 0; i < bufferPortionCount; i++)
            {
                notifications.Add(new NotificationPosition()
                {
                    Offset = bufferPortionSize - 1 + bufferPortionSize * i,
                    Event = new AutoResetEvent(false),
                });
            }
            captureBuffer.SetNotificationPositions(notifications.ToArray());
            WaitHandle[] waitHandles = new WaitHandle[notifications.Count];
            for (int i = 0; i < notifications.Count; i++)
            {
                waitHandles[i] = notifications[i].Event;
            }

            captureBuffer.Start(true);

            byte[] bufferPortion = new byte[bufferPortionSize];
            int bufferPortionIndex;
            DateTime lastNotificationTime = DateTime.MinValue;
            DateTime now;
            while (GetAsyncKeyState(VK_ESCAPE) == 0)
            {
                bufferPortionIndex = WaitHandle.WaitAny(waitHandles);

                captureBuffer.Read<byte>(bufferPortion, 0, bufferPortionSize, bufferPortionSize * bufferPortionIndex);

                now = DateTime.Now;
                System.Diagnostics.Debug.Write(String.Format("{0}\t{1}\n", bufferPortionIndex, (now - lastNotificationTime).Milliseconds));
                lastNotificationTime = now;

                stream.Write(bufferPortion, 0, bufferPortion.Length);
            }

            captureBuffer.Stop();

            for (int i = 0; i < notifications.Count; i++)
            {
                notifications[i].Event.Close();
            }

            captureBuffer.Dispose();
            directSoundCapture.Dispose();
            ds.Dispose();

            stream.Close();
            stream.Dispose();
        }
    }
}

[Edited by - hmassad on November 7, 2010 11:01:16 AM]