Record HTTP Audio stream to file

In C# I want to record an audio stream

I am doing something along the lines of:

HttpWebRequest req;
req = (HttpWebRequest)WebRequest.Create("http://url.com/stream");

Webresponse 开发者_如何学Pythonresp = req.GetResponse();
Stream s = resp.GetResponseStream();

fs = File.Exists(fileName)
    ? new FileStream(fileName, FileMode.Append)
    : new FileStream(fileName, FileMode.Create);

byte[] buffer = new byte[4096];

while (s.CanRead)
{
    Array.Clear(buffer, 0, buffer.Length);
    total += s.Read(buffer, 0, buffer.Length);
    fs.Write(buffer, 0, buffer.Length);
}

and the file size grows but can't be played back by VLC or any other program.

This is not my exact code I do a lot of error checking etc, but this gives the general idea.

    Array.Clear(buffer, 0, buffer.Length);
    total += s.Read(buffer, 0, buffer.Length);
    fs.Write(buffer, 0, buffer.Length);

You do not have to clear the whole array before you read - there's no point in doing this. But you have to check how many bytes you actually read, there's no guarantee the whole array is filled every time (and it probably won't):

    int bytesRead = s.Read(buffer, 0, buffer.Length);
    fs.Write(buffer, 0, bytesRead);
    total+=bytesRead;

Also whether the file plays (even when it is not corrupted anymore once you fix the file writing code) back depends on the format that you are downloading - what codec / file type is it?

THe problem is the streamed bits don't have context. When you stream to an application, there is a tacit agreement that you are dealing with file type X and the streaming program then tries to play the bits.

WHen you stream to a file, you have to add the context. One of the most important bits is the header identifying the type of file and other information.

If you can add the header, you can play the file from the file system. The header will not be part of the stream, as the server and client have agreed on what type fo file it it is already.

If you create a streaming player, you can possibly play back the bits you saved, as you negotiate the type. BUt to have it automagically work from file, you have to add the header.

Trying to save streamed MP3 audio to disk is essentially impossible without a detailed understanding of both the stream format and the file format for MP3. What you're getting from the stream is a series of "windowed" chunks of audio converted to frequency domain; the player receiving the stream converts the chunks back into time-domain audio on the fly and plays them one after the other.

To make an MP3 file, you would have to first write out a header containing the format information and then write each chunk of data. But most likely the format for storing these chunks in a file is different from the way in which they're compacted into a stream.

Sorry, but I would seriously advise you to give this up. One major reason that music services stream instead of offering file downloads is specifically because it's so difficult to save an MP3-type stream to disk (it would be a trivial matter to save an uncompressed audio stream to a WAV file).