如何获取mp3文件的持续时间而不播放或存储它们

Question

我正在构建一个wp8应用程序,可以在列表框中逐行播放诗歌.

假设我有20行诗歌在列表框中显示为20个项目.我有20个mp3文件(每行一个),我使用BackgroundAudioPlayer播放单个文件并选择列表框中的每个项目(诗).在播放这些mp3文件的过程中,有1-3秒的延迟,所以我找到了这些mp3文件的完整版本(20个文件合并为一个),逐行阅读诗歌.

我正在使用BackgroundAudioPlayer播放这个mp3文件.作为一个文件播放,我不能选择列表框中的每个项目,因为我不知道通过播放一个mp3文件的行号.

现在我想要的是在几秒钟内存储20个文件的持续时间,而无需存储和播放.这些文件位于链接中(http:123.com/1.mp3,/2.mp3, ...)

我使用带有绝对路径的AudioTrack然后使用持续时间属性,但它总是返回零.如何在不播放的情况下获取mp3文件的持续时间？

编辑: 在后面的代理我做了以下:

protected override void OnPlayStateChanged(BackgroundAudioPlayer player, AudioTrack track, PlayState playState)
{
switch (playState)
{
case PlayState.TrackReady:
TrackDuration tr = DataSource.Connection.Table<TrackDuration>().SingleOrDefault();
if (tr.IsGetTrackDuration)
{
if (player.Track != null)
{
player.Position = TimeSpan.FromSeconds(player.Track.Duration.TotalSeconds);
Recitation r = DataSource.Connection.Query<Recitation>("select * from Recitation where ID = " + player.Track.Title).SingleOrDefault();
r.AyaDuration = player.Track.Duration.TotalSeconds;
DataSource.saveRecitionDownloaded(r);
PlayNextTrack(player);
}
}
break;
}
NotifyComplete();
}

protected override void OnUserAction(BackgroundAudioPlayer player, AudioTrack track, UserAction action, object param)
{
switch (action)
{
case UserAction.Play:
   PlayTrack(player);
break;
case UserAction.Seek:
if (null!=player.Track)
player.Position = (TimeSpan)param;
break;
}
NotifyComplete();
}

private void PlayNextTrack(BackgroundAudioPlayer player)
{
 if (++currentTrackNumber >= audioTrack.Count)
   return;
 PlayTrack(player);
}

private void PlayTrack(BackgroundAudioPlayer player)
{
//If No Track then load Track
 if (audioTrack.Count == 0)
 {
     //Load Tracks and Add them into Track Play List
 }
if ((player.Track == null) || (player.Track.Title != audioTrack[currentTrackNumber].Title))
    player.Track = audioTrack[currentTrackNumber];

if ((player.Track != null) && (player.PlayerState != PlayState.Playing))
    player.Play();
}

问题是它播放了一些我不想要的文件.(tr.IsGetTrackDuration)总是如此,但我不知道它为什么会起作用？

Answer 1

MusicProperties类有一个持续时间的属性

 MusicProperties musicProperties = await file.Properties.GetMusicPropertiesAsync();
 outputText.AppendLine("Duration: " + musicProperties.Duration);