在 .NET 检索 MP3 的持续时间?
问题说明
我已经构建了一个 WPF 应用程序，用户可以在其中将 MP3 文件拖放到列表框上.我需要一种方法来计算播放列表的总持续时间.
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.
我应该使用哪些库?或者是否可以仅使用 .NET 框架?
Any libraries I should use? Or is it possible using only the .NET framework?
正确答案
经过大量理论分析，我找到了一种正确且无可争议地计算 mp3 文件时长的方法.
After lots of theorizing, I found a way to correctly and indisputably calculate a duration of an mp3 file.
让我首先重申为什么上述标准方法不起作用:
Let me first re-iterate why standard methods above won't work:
ID3 方法:并非所有文件都有 id3 标签，如果有，则可能没有设置持续时间字段.
ID3 method: not all files have id3 tags, and if they have it, they might not have duration field set in it.
通过读取一帧来估计 * 文件大小:不适用于 VBR 文件.
Estimating by reading one frame * file size: not gonna work for VBR files.
Xing header:不是所有文件都有.
Xing header: not all files have it.
通过 PCM 大小解码和确定它:我有 3 GB 以上的文件，我不会等到它解码.
Decoding and determining it via PCM size: I have 3 GB file, I'm not going to wait until it decodes.
我到处阅读，所有的东西都指向 NAudio.马克，感谢您的努力和干净的来源！但是，NAudio 主要建议的一种方法是使用 Mp3FileReader 读取文件并获取所有帧.问题:Mp3FileReader 在开始时创建一个 TOC，即使对于只有一天的小文件也需要永远:)
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 :)
Mark 建议我删除 TOC 创建，因为源可用，并且在执行此操作时，我发现了更简单的方法.这里是;不言自明:
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;
}
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