在UnitySynth上导入自定义Midis时为NullReference

因此，我从统一答案中下载了统一项目。链接在这里：

UnitySynth链接以统一答案下载页面

我已经完成了原型制作，但是尝试加载从网络下载的自定义Midi时遇到错误。

我得到了这些错误代码：

Error Loading Midi:
Midi Failed to Load!
UnityEngine.Debug:Log(Object)
CSharpSynth.Sequencer.MidiSequencer:LoadMidi(String, Boolean) (at Assets/Plugins/CSharpSynth/Sequencer/MidiSequencer.cs:153)
UnitySynthTest:Awake() (at Assets/Scripts/UnitySynthTest.cs:42)

NullReferenceException: Object reference not set to an instance of an object
CSharpSynth.Sequencer.MidiSequencer.Play () (at Assets/Plugins/CSharpSynth/Sequencer/MidiSequencer.cs:167)
UnitySynthTest.OnGUI () (at Assets/Scripts/UnitySynthTest.cs:161)

我很想知道一个简单的方法来将midis转换为mid.txt，作为演示中使用的示例。

编辑：

第一个错误代码（关于不加载midi的错误代码）来自此处：

public bool LoadMidi(string file, bool UnloadUnusedInstruments)
{
    if (playing == true)
        return false;
    MidiFile mf = null;
    try
    {
        mf = new MidiFile(file);
    }
    catch (Exception ex)
    {
        //UnitySynth

//THIS IS THE ERROR LINE **************************
            Debug.Log("Error Loading Midi:\n" + ex.Message);

return false;
    }
    return LoadMidi(mf, UnloadUnusedInstruments);
}

第二个关于空引用异常的原因来自：

    public void Play()
    {
        if (playing == true)
            return;
        //Clear the current programs for the channels.
        Array.Clear(currentPrograms, 0, currentPrograms.Length);
        //Clear vol, pan, and tune
        ResetControllers();
        //set bpm

// THIS IS THE ERROR LINE *****************************
     _MidiFile.BeatsPerMinute = 120;


        //Let the synth know that the sequencer is ready.
        eventIndex = 0;
        playing = true;
    }