LameMP3FileWriter: Unsupported encoding format MuLaw Parameter name: format - wav

Question

Trying to convert a 12 year old wav file to mp3,
8K, 8bit, Mono-channel, Mu-Law format, WAV
and I am getting this error in LameMP3FileWriter line:
LameMP3FileWriter: Unsupported encoding format MuLaw Parameter name: format
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;
}
}
Could anyone show me how to convert this type of wav to mp3?

Answer 1

You need to get your file converted to a more standard format before converting it to MP3. Use WaveFormatConversionStream.CreatePcmStream to go from mu law to linear PCM 16 bit. Then the next challenge will be that LAME probably won't like 8kHz audio, so upsample to at least 16kHz, possibly higher with either another WaveFormatConversionStream or MediaFoundationResampler.

Answer 2

I ended up using SOX and LAME exes instead to convert to usable wav file and then convert to mp3. It turned out to be an easy and effective solution. Here's the main part of the code:
// 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 command line utility:
URL: http://sox.sourceforge.net/
Version: SoX 14.4.2 released on 02/22/2015
LAME compiled command line utility:
URL: http://www.rarewares.org/mp3-lame-bundle.php
Version: LAME 3.99.5 released on 05/22/2014, Bundle compiled with Intel Compiler 14.0.3.
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.