Question

我试图在释放按钮后立即停止声音，但会发生的是该文件已完全播放。我不想像sp.Stop()那样突然停止声音。有没有办法做到这一点？

private void button1_MouseDown(object sender, MouseEventArgs e)
{
    if(sender == mk)
    {
        if(e.Button == MouseButtons.Left)
        {
            SoundPlayer sp = new SoundPlayer();

            sp.SoundLocation = (@"C:\my path\sound.wav");
            sp.Play();
        }
    }
}

private void button1_MouseUp(object sender, MouseEventArgs e)
{
    if(sender == mk)
    {
        if(e.Button == MouseButtons.Left)
        { /*some code here (without sp.Stop())*/ }
    }
}

Answer 1

我将您的问题解释为：

如何使用SoundPlayer淡出.wav文件的音频，而不是立即停止？

简短的回答是，您无法单独使用SoundPlayer。您需要使用winmm.dll库中的几个apis。

如果您对WPF感到满意，那么在其上使用MediaElement DoubleAnimation的卷属性可能是更好的方法。有关相关信息，请参阅this问题。

但是，如果您真的想使用WinForms，以下是一个应该有效的实现。

关于Form1的说明：

两个按钮，分别为startButton和stopButton
我用来淡出声音的名为timer1的计时器

以下是实现此功能的代码：

using System;
using System.Media;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{

    public partial class Form1 : Form
    {

        [DllImport("winmm.dll", EntryPoint = "waveOutGetVolume")]
        private static extern int WaveOutGetVolume(IntPtr hwo, out uint dwVolume);

        [DllImport("winmm.dll", EntryPoint="waveOutSetVolume")]
        private static extern int WaveOutSetVolume(IntPtr hwo, uint dwVolume);

        private SoundPlayer player = new SoundPlayer();

        // a crude delta time field
        private float totalElapsedTime;

        // tweak this value to determine how quickly you want the fade to happen
        private const float Velocity = 0.001f;

        public Form1()
        {
            this.InitializeComponent();

            // i was using 100 milliseconds as my "frame rate"
            this.timer1.Interval = 100;
            this.stopButton.Enabled = false;
        }

        private void startButton_Click(object sender, EventArgs e)
        {
            // sets the audio device volume to the max.
            // this is not the computer's volume so it won't
            // blast out your ear drums by doing this unless you
            // have the computer volume super high - which is not this
            // code's fault
            WaveOutSetVolume(IntPtr.Zero, uint.MaxValue);

            this.startButton.Enabled = false;
            this.stopButton.Enabled = true;

            this.totalElapsedTime = 0f;
            this.player.SoundLocation = @"Music File.wav";
            this.player.Load();
            this.player.Play();
        }

        private void stopButton_Click(object sender, EventArgs e)
        {
            // being the stop
            this.timer1.Start();
            this.stopButton.Enabled = false;
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            // amount to interpolate (value between 0 and 1 inclusive)
            float amount = Math.Min(1f, this.totalElapsedTime * Velocity);

            // the new channel volume after a lerp
            float lerped = Lerp(ushort.MaxValue, 0, amount);

            // each channel's volume is actually represented as a ushort
            ushort channelVolume = (ushort)lerped;

            // the new volume for all the channels
            uint volume = (uint)channelVolume | ((uint)channelVolume << 16);

            // sets the volume 
            WaveOutSetVolume(IntPtr.Zero, volume);

            // checks if the interpolation is finished
            if (amount >= 1f)
            {
                // stop the timer 
                this.timer1.Stop();

                // stop the player
                this.player.Stop();

                // stop is complete so let user start again
                this.startButton.Enabled = true;
            }

            // add the elapsed milliseconds (very crude delta time)
            this.totalElapsedTime += this.timer1.Interval;
        }

        public static float Lerp(float value1, float value2, float amount)
        {
            // does a linear interpolation
            return (value1 + ((value2 - value1) * amount));
        }

    }

}

希望这应该是不言自明的。我想大多数人都会认为这是一个原始的游戏循环方式。方法，但似乎运作良好。值得注意的是，调整淡入淡出发生的速度是Velocity常数。

代码设置为淡出超过1秒。通过查看timer1.Interval和Velocity可以轻松搞清楚这一点。在1000毫秒（10个计时器滴答）之后，1000 * 0.001 = 1，这导致停止代码完成。

更改timer1.Interval的唯一原因是更多＆＃34;淡化＆＃34;发生。当前设置在停止之前会进行10次音量衰减。

如何使用SoundPlayer淡出.wav文件的音频而不是立即停止？

1 个答案: