流包装，使流可查找？ [英] Stream wrapper to make Stream seekable?

问题描述

我有一个只读的System.IO.Stream 的实现，是不是可查找（和它的位置始终返回0）。我需要将其发送给消费者，做一些寻找操作（即，将位置设置）在流。这是不是一个巨大的寻求 - 从当前位置说+/- 100。是否有一个现有的流包装，将增加一个缓冲能力，流于简单查找操作？

I have a readonly System.IO.Stream implementation that is not seekable (and it's Position always returns 0). I need to send it to a consumer that does some Seek operations (aka, sets the Position) on the stream. It's not a huge seek -- say +/- 100 from the current position. Is there an existing Stream wrapper that will add a buffering ability to the stream for simple Seek operations?

更新：我要补充一点，我的消费者是n音讯Mp3FileReader。我真的只是需要一种方法来发挥（慢，并且无限期地）流的MP3。我认为这是n音讯希望能够寻求随意的数据源中的错误。

Update: I should add that my consumer is the NAudio Mp3FileReader. I really just need a way to play a (slowly and indefinitely) streaming MP3. I think it's a bug that NAudio expects to be able to seek their data source at will.

推荐答案

寻找前锋是很容易（只读），但你不能寻求倒退没有缓冲。也许只是：

Seeking forwards is easy enough (just read), but you can't seek backwards without buffering. Maybe just:

using(var ms = new MemoryStream()) {
    otherStream.CopyTo(ms);
    ms.Position = 0;
    // now work with ms
}

此，但是，只适合小至中度流（未标），已知会结束（其流是不需要做）。如果你需要一个更大的流，的FileStream 到一个临时文件的工作，但显著更多的是IO密集型的。

This, however, is only suitable for small-to-moderate streams (not GB), that are known to end (which streams are not requires to do). If you need a larger stream, a FileStream to a temp-file would work, but is significantly more IO-intensive.

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