Question

我希望在WPF中顺利播放视频。我正在使用MediaElement播放视频。我读了this post，建议定期更改MediaElement.Position以模仿倒带行为。

我尝试使用代码更改MediaElement.Position

的位置

private void Button_Click(object sender, RoutedEventArgs e)
{
    mePlayer.Pause();                               //Pause the media player first
    double m = 1 / frameRate;                       //Calculate the time for each frame
    double t = 120;                                 //Total length of video in seconds
    mePlayer.Position = TimeSpan.FromMinutes(2);    //Start video from 2 min
    while (t >= 60)                                 //Check if time exceeds 1 min
    {
        t = t - m;                                  //Subtract the single frame time from total seconds
        mePlayer.Position = TimeSpan.FromSeconds(t);//set position of video
    }
}

在上面的代码中，我试图从2分钟到1分钟向后播放视频。它在mePlayer.Position = TimeSpan.FromSeconds(t)上给了我'System.OverflowException'。

如果有人知道如何在WPF中向后播放视频，请帮助我实现此效果。谢谢。

Answer 1

为了顺利完成，您应该使用function validItems(items) { // create a valid items array. This will make maintaining valid item codes easier. and keep your code readable. var valid = ["IT00","0144","6A1L","4243","O3D5","44SG","CE64","54FS","4422"]; var error = false; for (i = 0; i < items.length; i++) { // Type safe test. Always use 3 === isntead of == your test would have returned true on eveyrthing. if (error === false) { if(valid.indexOf(items[i]) === -1) { // immedeately escape return items[i]; } /*else {// Totally uneccesary error = false; } } else { // not needed here. this also escaped your loop after first iteration. if (error !== false) {return error;} else {return "";} }*/ } // we return here because we know the loop is done then. return error; } var items = ["IT00","0144","6A1L"]; alert(validItems(items));。假设帧速率是24 fps，则意味着每1/24 = 0.0416秒或大约42毫秒是一帧。因此，如果您的计时器每42ms计时一次，您可以向后移动Timer：

XAML：

mePlayer.Position

代码：

<MediaElement x:Name="mePlayer" Source="C:\Sample.mp4"
              LoadedBehavior="Manual" ScrubbingEnabled="True"/>

如何在WPF中向后播放视频？

1 个答案: