Question

有时我在尝试获取BackgroundAudioPlayer.Instance的位置时遇到异常。它很少发生，但我已经能够获得StackTrace。奇怪的是，这段代码在播放曲目时每秒执行一次。可能是造成此错误的原因是什么？

我正在使用StackTrace。

System.SystemException: HRESULT = 0xC00D36C4 ---> System.Runtime.InteropServices.COMException: Exception from HRESULT: 0xC00D36C4 at 
Microsoft.Phone.BackgroundAudio.Interop.IAudioPlaybackManager.get_CurrentPosition() at 
Microsoft.Phone.BackgroundAudio.BackgroundAudioPlayer.get_Position() --- End of inner exception stack trace --- at 
Microsoft.Phone.BackgroundAudio.BackgroundAudioPlayer.get_Position() at 
MC.PodCast.Common.ViewModel.PlayerViewModel.UpdateTrackPosition() at 
MC.PodCast.Common.ViewModel.PlayerViewModel.ReactToBackgroundAudioPlayer() at 
MC.PodCast.Common.ViewModel.PlayerViewModel.Initialize() at 
MC.PodCast.Common.ViewModel.PlayerViewModel.<<get_InitializeCommand>b__5>d__6.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>b__0(Object state)

当然，我使用的代码很简单。

public void UpdateTrackPosition()
{
    if (_backgroundAudioPlayer != null && _backgroundAudioPlayer.Track != null)
    {
        Position = _backgroundAudioPlayer.Position;
    }
    else
    {
        Position = null;
    }
}

Answer 1

该代码链接到MF_MEDIA_ENGINE_ERR_SRC_NOT_SUPPORTED，但我猜你确实有声音。

我发现BackgroundAudioPlyer可能非常奇怪。我使用“安全”扩展方法包裹了大部分电话。

实施例

public static PlayState PlayerStateSafe(this BackgroundAudioPlayer source)
{
    PlayState state;
    try
    {
        state = source.PlayerState;
    }
    catch (InvalidOperationException)
    {
        state = PlayState.Unknown;
    }
    return state;

}

是什么导致BackgroundAudioPlayer.get_Position（）的System.Runtime.InteropServices.COMException？

1 个答案: