写音频从文件中的MemoryStream [英] write audio to memorystream from file

问题描述

我想这个文件发送到OutputStream的，但想不通为什么它吐出基本上是空的MP3文件。正如你可以看到我会得到一个异常过早地关闭流，所以我都注释掉了现在。任何指针赞赏。

 使用（的FileStream mp3file = File.OpenRead（NEWFILE））
 {
上下文.Response.AddHeader（内容传输编码，二进制）; 
 context.Response.ContentType =音频/ MPEG; 
 MemoryStream的memStream =新的MemoryStream（）; 
字节[]字节=新的字节[mp3file.Length] 
 memStream.SetLength（mp3file.Length）; 
 mp3file.Read（memStream.GetBuffer（），0，（int）的mp3file.Length）; 
 memStream.Write（字节，0，（int）的mp3file.Length）; 
 //mp3file.Close（）; 
 memStream.WriteTo（context.Response.OutputStream）; 
 //memStream.Close（）; 
 
} 
  

解决方案

这部分的问题：

 字节[]字节=新的字节[mp3file.Length] 
 ... 
 //这里你读入内存流缓冲区... 
 mp3file.Read（memStream.GetBuffer（），0，（INT）mp3file.Length）; 
 //在这里，你的字节数组全零的覆盖它！ 
 memStream.Write（字节，0，（int）的mp3file.Length）; 
  

您不应该的假设的是单个呼叫读将实际读到的一切反正虽然。目前尚不清楚你正在使用的.NET版本，但是如果你使用.NET 4.0或更高版本，可以使用的 Stream.CopyTo ，使其更简单。

这是也的不清楚为什么您使用的是的MemoryStream 可言。你为什么不只是直接复制到输出流

  mp3File.CopyTo（context.Response.OutputStream）？; 
  

或者，如果你使用.NET的旧版本：

 字节[]缓冲区=新的字节[16 * 1024]; //对于〔实施例... 
 INT读取动作; 
而（（读取动作= mp3File.Read（缓冲液，0，buffer.Length））大于0）
 {
 context.Response.OutputStream.Write（缓冲液，0，读取动作）; 
} 
  

（这是几乎相当于 CopyTo从）

I'm trying to send this file to the outputstream but cannot figure out why it spits out basically an empty mp3 file. As you can see I would get an exception closing the stream prematurely so I have commented out for now. Any pointers appreciated.

using (FileStream mp3file = File.OpenRead(newFile))
                {
                    context.Response.AddHeader("content-transfer-encoding", "binary");
                    context.Response.ContentType = "audio/mpeg";
                    MemoryStream memStream = new MemoryStream();
                    byte[] bytes = new byte[mp3file.Length];
                    memStream.SetLength(mp3file.Length);
                    mp3file.Read(memStream.GetBuffer(), 0, (int)mp3file.Length);
                    memStream.Write(bytes, 0, (int)mp3file.Length);
                    //mp3file.Close();
                    memStream.WriteTo(context.Response.OutputStream);
                    //memStream.Close();

                }

解决方案

This part is the problem:

 byte[] bytes = new byte[mp3file.Length];
 ...
 // Here you're reading into the memory stream buffer...
 mp3file.Read(memStream.GetBuffer(), 0, (int)mp3file.Length);
 // And here you're overwriting it with the byte array full of zeroes!
 memStream.Write(bytes, 0, (int)mp3file.Length);

You shouldn't assuming that a single call to Read will actually read everything anyway though. It's not clear which version of .NET you're using, but if you're using .NET 4 or higher, you can use Stream.CopyTo to make it simpler.

It's also unclear why you're using a MemoryStream at all. Why don't you just copy straight to the output stream?

mp3File.CopyTo(context.Response.OutputStream);

Or if you're using an older version of .NET:

byte[] buffer = new byte[16 * 1024]; // For exmaple...
int bytesRead;
while ((bytesRead = mp3File.Read(buffer, 0, buffer.Length)) > 0)
{
    context.Response.OutputStream.Write(buffer, 0, bytesRead);
}

(This is pretty much the equivalent of CopyTo.)

这篇关于写音频从文件中的MemoryStream的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！