从流生成波形

Question

我需要根据多个音频文件（.wav / .mp3）生成波形。我目前正在使用NAudio，但我遇到了一些问题。我不能使用文件的路径，因为我不允许将文件上传到服务器，大多数浏览器阻止路径（安全原因），所以我的方法是使用流或内存流。我发现这个project做了一些非常相似的事情，但是如果没有文件的直接路径，我就无法让它工作。 这是我从用户那里获取文件的代码

[HttpPost]
    public ActionResult UploadAudioFile()
    {
        if (Request.Files.Count > 0)
        {
            List<MusicViewModel> list = new List<MusicViewModel>();
            var supportedFileTypes = new[] { "audio/mp3", "audio/wav" };
            foreach (string file in Request.Files)
            {
                var _file = Request.Files[file];
                if (_file != null)
                {
                    var contentType = _file.ContentType.ToLower();
                    if (supportedFileTypes.Contains(contentType))
                    {

                        var s = _file.InputStream;                           

                        var name = _file.FileName;
                        var song = new MusicViewModel();
                        System.Drawing.Image img;
                        if (contentType.Equals("audio/mp3"))
                        {
                            song = _musicRepo.GetMetaDataFromMp3File(s, name);
                            img = _musicRepo.GenerateWaveForm(s);
                        }
                        else if (contentType.Equals("audio/wav"))
                        {
                            song = _musicRepo.GetMetaDataFromWavFile(s, name);
                            img = _musicRepo.GenerateWaveForm(s);
                        }
                        if (song != null)
                        {
                            list.Add(song);
                        }

                    }
                    else
                    {
                        return Json(new { isSuccess = false, errorMsg = "We only allow audio files of .mp3 or .wav format. You have attempted to upload a file with " + contentType + "." });
                    }
                }
            }
            return Json(new { isSuccess = true, musicList = list });
        }

        return Json(new { isSuccess = false });
    }

然后在我的音乐库中使用GenerateWaveForm

public Image GenerateWaveForm(Stream stream)
    {
        Image img = null;
        WaveFormRenderer wr = new WaveFormRenderer();
        try
        {
            img = wr.Render(stream);
        }
        catch (Exception ex)
        {

            throw;
        }
        return img;
    }

我正在按照此class的方法，但我收到错误“不是WAVE文件 - 没有RIFF标题”。这是我创建异常的类

public Image Render(Stream stream)
    {
        int destBytesPerSample = 0;
        long samples;
        WaveStream readerStream = new WaveFileReader(stream);

        if (readerStream.WaveFormat.Encoding != WaveFormatEncoding.Pcm && readerStream.WaveFormat.Encoding != WaveFormatEncoding.IeeeFloat)
        {
            readerStream = WaveFormatConversionStream.CreatePcmStream(readerStream);
            readerStream = new BlockAlignReductionStream(readerStream);
            var sourceBytesPerSample = (readerStream.WaveFormat.BitsPerSample / 8) * readerStream.WaveFormat.Channels;
            SampleChannel sampleChannel = new SampleChannel(readerStream, false);

            destBytesPerSample = 4 * sampleChannel.WaveFormat.Channels;
            samples = destBytesPerSample * (readerStream.Length / sourceBytesPerSample);
            var peakProvider = getPeakProvider();

            WaveFormRendererSettings settings = GetRendererSettings();
            var samplesPerPixel = (int)(samples / settings.Width);
            var stepSize = settings.PixelsPerPeak + settings.SpacerPixels;
            //peakProvider.Init(reader, samplesPerPixel * stepSize);
            return Render(peakProvider, settings);
        }
        return null;
    }

当我尝试在方法Render

中的第3行中创建对象readerStream时发生异常