将通过HTTP流式传输的wav实时转换为mp3

Question

背景:我正在使用一个返回MIME类型为的数据的服务audio/wav.我需要为这个音频提供一个播放机制(目前作为MVC应用程序构建).举个例子,我的端点看起来像https://audio.fooservice.com/GetAudio?audioId=123

音频为8kHz,1通道u-law.

由于使用HTML5 <audio>标记时浏览器的格式支持不同,我无法使用原始的u-law wav,因为Internet Explorer不会播放它.

我提出的解决方案是从源格式到mp3进行实时转换.

我在这里和NAudio论坛中拼凑了一个部分工作的解决方案来解决各种其他问题,但它引发了一个例外情况,如下面的评论中所述:

private void NAudioTest(string url)
{
    Stream outStream = new MemoryStream();
    var format = WaveFormat.CreateMuLawFormat(8000, 1);

    using (Stream ms = new MemoryStream())
    {
        var request = (HttpWebRequest)WebRequest.Create(url);
        request.KeepAlive = false;
        request.ProtocolVersion = HttpVersion.Version10;

        using (Stream stream = request.GetResponse().GetResponseStream())
        {
            using (var reader = new RawSourceWaveStream(stream, format))
            {
                // reader is not seekable; we need to convert to a byte array to seek
                var bytes = reader.ToByteArray();

                // create a new stream from the byte aray
                var seekableStream = new MemoryStream(bytes);

                // instantiating a WaveFileReader as follows will throw an exception:
                // "System.FormatException: Not a WAVE file - no RIFF header"
                using (var waveReader = new WaveFileReader(seekableStream))
                {
                    using (var pcmStream = WaveFormatConversionStream.CreatePcmStream(waveReader))
                    {
                        var pcmBytes = pcmStream.ToByteArray();
                        var mp3 = pcmBytes.ToMp3();
                    }
                }
            }
        }
    }
}

public static class StreamExtensions
{
    public static byte[] ToByteArray(this Stream stream)
    {
        var ms = new MemoryStream();
        var buffer = new byte[1024];
        int bytes = 0;

        while ((bytes = stream.Read(buffer, 0, buffer.Length)) > 0)
            ms.Write(buffer, 0, bytes);

        return ms.ToArray();
    }
}

public static class ByteExtensions
{
    public static byte[] ToMp3(this byte[] bytes)
    {
        using (var outStream = new MemoryStream())
        {
            using (var ms = new MemoryStream(bytes))
            {
                using (var reader = new WaveFileReader(ms))
                {
                    using (var writer = new LameMP3FileWriter(outStream, reader.WaveFormat, 64))
                    {
                        reader.CopyTo(writer);
                        return outStream.ToArray();
                    }
                }
            }
        }
    }
}

我大部分时间一直在讨论这个问题,我觉得我正在将不必要的复杂性引入到看起来应该相当直接的东西中.

任何帮助将非常感激.

注意:我无法更改源格式,并且支持IE是必需的.

编辑:我解决了RIFF异常并且能够产生MP3的流,但它只是白噪声.希望我也可以解决这个问题.我的新代码如下:

[HttpGet]
public ActionResult GetMp3(string url)
{
    if (String.IsNullOrWhiteSpace(url))
        return null;

    var muLawFormat = WaveFormat.CreateMuLawFormat(8000, 1);
    var compressedStream = new MemoryStream();

    using (var ms = new MemoryStream())
    {
        var request = (HttpWebRequest)WebRequest.Create(url);
        request.KeepAlive = false;
        request.ProtocolVersion = HttpVersion.Version10;

        using (Stream webStream = request.GetResponse().GetResponseStream())
        {
            var buffer = new byte[4096];
            int read;
            while (webStream != null && (read = webStream.Read(buffer, 0, buffer.Length)) > 0)
                ms.Write(buffer, 0, read);
        }

        ms.Position = 0;

        using (WaveStream wav = WaveFormatConversionStream.CreatePcmStream(new RawSourceWaveStream(ms, muLawFormat)))
        using (var mp3 = new LameMP3FileWriter(compressedStream, new WaveFormat(), LAMEPreset.MEDIUM_FAST))
            wav.CopyTo(mp3);
    }

    compressedStream.Seek(0, 0);
    return new FileStreamResult(compressedStream, "audio/mpeg");
}

Answer 1

这对我有用（我需要做你想做的事情）。希望这也对其他人有帮助。我将 NAudio 与 LAME 一起使用。

您必须确保将 libmp3lamexx.dll 文件复制到网络服务器的 BIN 位置或 %PATH% 变量中的某个文件夹，否则它将无法工作。

        string sq = /* URL of WAV file (http://foo.com/blah.wav) */

        Response.ContentType = "audio/mpeg";

        using (WebClient wc = new WebClient())
        {
            if (!sq.ToLower().EndsWith(".wav"))
            {
                byte[] rawFile = wc.DownloadData(sq.Trim());
                Response.OutputStream.Write(rawFile, 0, rawFile.Length);
            }
            else
            {
                using (var wavReader = new WaveFileReader(new MemoryStream(wc.DownloadData(sq.Trim()))))
                {
                    try
                    {
                        using (var wavWriter = new LameMP3FileWriter(Response.OutputStream, wavReader.WaveFormat, LAMEPreset.ABR_128))
                        {
                            wavReader.CopyTo(wavWriter);
                        }
                    }
                    catch (ArgumentException)
                    {
                        var newFormat = new WaveFormat(wavReader.WaveFormat.SampleRate, 16, 2);

                        using (var pcmStream = new WaveFormatConversionStream(newFormat, wavReader))
                        {
                            using (var wavWriter = new LameMP3FileWriter(Response.OutputStream, pcmStream.WaveFormat, LAMEPreset.ABR_128))
                            {
                                pcmStream.CopyTo(wavWriter);
                            }
                        }
                    }
                }
            }

            Response.Flush();
            Response.End();
        }