LameMP3FileWriter：不支持的编码格式 MuLaw 参数名称：格式

Question

正在尝试将 12 年前的 wav 文件转换为 mp3，

8K，8 位，单声道，Mu-Law 格式，WAV

我在 LameMP3FileWriter 行中收到此错误：

LameMP3FileWriter：不支持的编码格式 MuLaw 参数名称：格式

static void Main(string[] args)
{
    string wavFilePath = @"C:\temp\Message.wav";
    string mp3FilePath = @"C:\temp\Message.mp3";
    if (!File.Exists(mp3FilePath))
    {
        byte[] bytearrwav = File.ReadAllBytes(wavFilePath);
        byte[] bytearrmp3 = ConvertWavToMp3(bytearrwav);
        File.WriteAllBytes(mp3FilePath, bytearrmp3);
    }
}

public static byte[] ConvertWavToMp3(byte[] wavFile)
{
    try
    {
        using (var retMs = new MemoryStream())
        using (var ms = new MemoryStream(wavFile))
        using (var rdr = new WaveFileReader(ms))
        using (var wtr = new LameMP3FileWriter(retMs, rdr.WaveFormat, 128))
        {
            rdr.CopyTo(wtr);
            return retMs.ToArray();
        }
    }
    catch (Exception ex)
    {
        Console.WriteLine(ex.Message);
        return null;
    }
}

谁能告诉我如何将这种类型的 wav 转换为 mp3？

Answer 1

在将文件转换为 MP3 之前，您需要将文件转换为更标准的格式。使用 WaveFormatConversionStream.CreatePcmStream 从 mu 律转到线性 PCM 16 位。那么下一个挑战将是 LAME 可能不喜欢 8kHz 音频，所以上采样到至少 16kHz，可能更高，或者 WaveFormatConversionStream 或 MediaFoundationResampler.

Answer 2

我最终使用 SOX 和 LAME exe 来转换为可用的 wav 文件，然后再转换为 mp3。事实证明这是一个简单有效的解决方案。这是代码的主要部分：

            // create temp file
            tempFile = this.FolderFromFile(inputFileAndPath) + "tempFile.wav";

            // Part 1:  Convert mu-Law WAV to floating point WAV
            // perform work with no display of console window
            // Example:  SOX.EXE  MachMsg1.wav  -e floating-point  MsgFloatingPoint.wav
            using (this)
            {
                System.Diagnostics.Process proc = new System.Diagnostics.Process
                {
                    StartInfo = new System.Diagnostics.ProcessStartInfo
                    {
                        FileName = soxFileAndPath,
                        Arguments = inputFileAndPath + "  " + "-e floating-point" + "  " + tempFile,
                        UseShellExecute = false,
                        RedirectStandardOutput = true,
                        CreateNoWindow = true
                    }
                };
                proc.Start();
            }


            // Part 2:  Convert floating point WAV to MP3 using highest quality possible
            // perform work with no display of console window
            // Example:  LAME.EXE  -V4  MsgFloatingPoint.wav  MsgFloatingPoint.mp3
            using (this)
            {
                System.Diagnostics.Process proc = new System.Diagnostics.Process
                {
                    StartInfo = new System.Diagnostics.ProcessStartInfo
                    {
                        FileName = lameFileAndPath,
                        Arguments = "-V4" + "  " + tempFile + "  " + outputFileAndPath,
                        UseShellExecute = false,
                        RedirectStandardOutput = true,
                        CreateNoWindow = true
                    }
                };
                proc.Start();
            }

SOX 命令行实用程序： URL: http://sox.sourceforge.net/

版本：SoX 14.4.2 发布于 02/22/2015

LAME 编译的命令行实用程序： URL: http://www.rarewares.org/mp3-lame-bundle.php

版本：LAME 3.99.5 于 05/22/2014 发布，Bundle 使用 Intel Compiler 14.0.3 编译。

  Hydrogenaudio recommended settings
      -- Best quality, "archiving"2 : -b 320 
           CBR 320 is the strongest setting for MP3, with the lowest risk of artifacts. With the exception of a few situations,
           quality is rarely better than the highest VBR profiles described below. 
      -- High quality, HiFi, home or quiet listening : -V0 (avg. 245 kbps) or -V1 (avg. 225 kbps) or -V2 (avg. 190 kbps) or  -V3 (avg. 175 kbps). 
           These settings are considered to produce transparent encoding (transparent = most people can't distinguish the MP3
           from the original in an ABX blind test). Audible differences between these presets exist, but are rare. 
      -- Portable, background noise and low bitrate requirement, small sizes : -V4 (avg. 160 kbps) or -V5 (avg. 130 kbps)
           or -V6 (avg. 115 kbps) -V6 produces an "acceptable" quality, while -V4 should be close to perceptual transparency. 
      -- Very low bitrate, small sizes, eg. for voice, radio, mono encoding : --abr 80 (stereo) or --abr 56 -m m (mono) 
           For very low bitrates, up to 100kbps, ABR is most often the best solution.

LameMP3FileWriter：不支持的编码格式 MuLaw 参数名称：格式

LameMP3FileWriter: Unsupported encoding format MuLaw Parameter name: format

wav

naudio

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