在转换过程中将nAudio WAV转换为MP3 muLaw错误

Question

我正在通过Web服务成功捕获WAV文件，并能够在Windows 7计算机上播放该文件。现在，我需要获取相同的WAV文件并将其转换为MP3文件。这是失败的。我尝试将文件作为WAV检索（上图），然后使用-

WaveStream PCMStream = WaveFormatConversionStream.CreatePcmStream（reader）;

将此muLaw转换为PCM。

此操作失败，并附带错误。我曾尝试直接使用LameMP3FileWriter进行转换，但这也无法告诉我“ muLaw格式无法转换为MP3。

我想念的是什么？代码片段

 private void WriteMP3(string iNum, string CallId)
    {
        //construct the replay URL using the iNum
        string url = "http://" + _VerintServer + "/searchapi?command=replay&id=" + iNum;

        // name the new mp3 file
        string mp3File =_basePath + "mp3\\" + CallId + ".mp3";
        string tempWav = _basePath + "mp3\\" + CallId + ".wav";
        string tempPCM = _basePath + "mp3\\" + CallId + "_PCM.wav";

        //issue the web service request
        HttpWebRequest request = (HttpWebRequest)System.Net.WebRequest.Create(url);

        //retrieve the content type as raw PCM (.wav)
        request.ContentType = "audio/wav";

        //encode and include the basic authentication credentials
        string encoded = System.Convert.ToBase64String(System.Text.Encoding.GetEncoding("ISO-8859-1").GetBytes(_username + ":" + _password));
        request.Headers.Add("Authorization", "Basic " + encoded);

        //retrieve the response
        HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();

        //copy the stream of bytes to the local directory using the CallId as the file name
        if (request.HaveResponse)
        {
            //create a temporary wav file 
            using (var receiveStream = response.GetResponseStream())
            {
                using (var PStream = new FileStream(tempWav, FileMode.Create,FileAccess.Write))
                {
                    receiveStream.CopyTo(PStream);
                }
            }

            WaveToPCM(tempWav, tempPCM);
            WaveToMP3(tempPCM, mp3File, 128);
        }
        return;
    }

    //Convert muLaw WAV to PCM
    private void WaveToPCM(string waveFileName, string pcmFileName)
    {
        using (var reader = new CueWaveFileReader(waveFileName))
        {
            WaveStream PCMStream = WaveFormatConversionStream.CreatePcmStream(reader);
            using (var PStream = new FileStream(pcmFileName, FileMode.Create, FileAccess.Write))
            {
               PCMStream.CopyTo(PStream);
            }            
        }           
        return;
    }

    // Convert WAV to MP3 using libmp3lame library
    public void WaveToMP3(string waveFileName, string mp3FileName, int bitRate = 128)
    {
        using (var reader = new WaveFileReader(waveFileName))
        using (var writer = new LameMP3FileWriter(mp3FileName, reader.WaveFormat, bitRate))
            reader.CopyTo(writer);
    }

堆栈跟踪：

{“ $ id”：“ 1”，“ Message”：“发生错误。”，“ ExceptionMessage”：“非WAVE文件-没有RIFF标头”，“ ExceptionType”：“ System.FormatException”，“ StackTrace“：”在NAudio.FileFormats.Wav.WaveFileChunkReader.ReadRiffHeader（BinaryReader br）\ r \ n在NAudio.FileFormats.Wav.WaveFileChunkReader.ReadWaveHeader（Stream stream）\ r \ n在NAudio.Wave.WaveFileReader..ctor（在C：\ Codebank \ DataAccess \中的NAudio.Wave.WaveFileReader..ctor（String waveFile）\ r \ n在DataServices.Controllers.RecordingsController.WaveToMP3（String waveFileName，String mp3FileName，Int32 bitRate）处输入流InputStream）\ r \ n DataServices \ Controllers \ RecordingsController.cs：行179 \ r \ n，位于DataServices.Controllers.RecordingsController.WriteMP3（String iNum，

Answer 1

在WaveToPcm函数中，您只是将原始样本写入文件中。您需要使用WaveFileWriter.CreateWaveFile传入PCMStream来制作可以传递给LAME MP3 Writer的16位PCM WAV文件]

Answer 2

谢谢马克。我现在已成功将muLaw编码的WAV文件转换为原始PCM，如下面的代码所示。

        //Convert muLaw WAV to PCM
    private void WaveToPCM(string waveFileName, string pcmFileName)
    {
        using (var reader = new WaveFileReader(waveFileName))
        {

           WaveStream PCMStream = WaveFormatConversionStream.CreatePcmStream(reader);
            WaveFileWriter.CreateWaveFile(pcmFileName, PCMStream);        
        }           
        return;
    }