我有建立一个WPF应用程序，用户可以拖放MP3文件到列表框。我需要一种方法来计算播放列表的总时间。

I have build a WPF application where users can drag and drop MP3 files onto a listbox. I need a way to calculate the total duration of the playlist.

我应该使用任何库？或者只使用了.NET框架是这可能吗？

Any libraries I should use? Or is it possible using only the .NET framework?

推荐答案

经过大量的理论，我发现了一种正确和无可争议地计算一个mp3文件的时间。

After lots of theorizing, I found a way to correctly and indisputably calculate a duration of an mp3 file.

首先，我要再次重申，为什么标准方法上面将无法工作：

Let me first re-iterate why standard methods above won't work:

ID3方法：不是所有的文件都ID3标签，如果他们有，他们可能没有时间字段将其设置

ID3 method: not all files have id3 tags, and if they have it, they might not have duration field set in it.

估计读一帧*文件大小：对VBR文件不是要去工作

Estimating by reading one frame * file size: not gonna work for VBR files.

兴头：不是所有的文件都有它

Xing header: not all files have it.

解码，并通过PCM大小决定的：我有3+ GB的文件，我不会等到它去codeS

Decoding and determining it via PCM size: I have 3+ GB file, I'm not going to wait until it decodes.

我读无处不在，所有的东西导致n音讯。马克，感谢您的好功夫的清洁能源！然而，一个方法，大多与n音讯建议是阅读使用Mp3FileReader一个文件，获取所有帧。问题：Mp3FileReader在开始创建TOC并且需要永远，即使只有一天小档案：）

I read everywhere and all things lead to NAudio. Mark, THANKS for the good effort and clean source! However, a method that is mostly suggested with NAudio is to read a file using Mp3FileReader and get all frames. Problem: Mp3FileReader creates a TOC at the start and that takes forever, even for small files of only ONE day :)

马克建议我删除TOC创建，因为源代码是可用的，并且在做的过程中，我发现很多简单的方法。这里是;是不言自明的：

Mark suggested that I remove TOC creation, since source is available, and while doing it, I found much simpler method. Here it is; is speaks for itself:

    double GetMediaDuration(string MediaFilename)
    {
        double duration = 0.0;
        using (FileStream fs = File.OpenRead(MediaFilename))
        {
            Mp3Frame frame = Mp3Frame.LoadFromStream(fs);
            if (frame != null)
            {
                _sampleFrequency = (uint)frame.SampleRate;
            }
            while (frame != null)
            {
                if (frame.ChannelMode == ChannelMode.Mono)
                {
                    duration += (double)frame.SampleCount * 2.0 / (double)frame.SampleRate;
                }
                else
                {
                    duration += (double)frame.SampleCount * 4.0 / (double)frame.SampleRate;
                }
                frame = Mp3Frame.LoadFromStream(fs);
            }
        }
        return duration;
    }