I created this due to someone on the forum asking about the format. You can download the encoder and decoder for MP3HD here:
HTML Code:
http://mp3hd-toolkit.soft32.com/
Known bugs:

When telling dBpoweramp to write ID3 tags to the file, only the lossy portion of the MP3 is saved. Even with the
Code:
-nodbtag
switch and writing tags using the
Code:
-id3in
switch it still stripts out the lossless portion stored in the tag.

I wouldn't recommend anyone using this encoder as the correction data is in the ID3 tag, because mp3 doesn't allow frame sizes large enough. Therefore, your lossless collection could too easily be lost with a basic mass-tagging operation.

The lossless part of the codec is stored in ID3v2 tags.

The size of ID3v2 tags is limited to 256MB by specifications; as a result, the lossless part of an mp3hd file may not be over 256MB.

You have been warned!

On the flipside, you apparently get a true Fraunhofer MP3 encoder for normal MP3 if you tag files, so there’s that…

If you want to only encode to lossless, just use the cli encoder, uncheck Write Tags, place .mp3 only in the encoder.txt file, and the switches
Code:
-if [infile] -of "[outfile]"
.

Dynamic CLI below:

Code:
[codec]
.mp3
mp3hdEncoder.exe

[msgifnoencoder]
Before using this encoder MP3HDEncoder.exe must first be downloaded (Google "Thomson mp3HD software Toolkit", or go here: http://mp3hd-toolkit.soft32.com/ ).

[label]
4
0
Mode

[radio&slider]
4
36
292
1
26
0
VBR + Correction

13
VBR5 ~114 kbps (0.3%>FLAC)
-mode 5
VBR4 ~137 kbps (2.0%>FLAC)
-mode 4
VBR3 ~147 kbps (2.2%>FLAC)
-mode 3
VBR2 ~188 kbps (2.0%>FLAC)
-mode 2
VBR1 ~216 kbps (5.1%>FLAC)
-mode 1
[/sliderend]
99
0
CBR (common CBR)

8
96 kbps (min)
-br 96000 
112 kbps
-br 112000 
128 kbps
-br 128000 
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-br 144000 
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-br 160000 
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-br 176000 
192 kbps
-br 192000 
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-br 224000 
256 kbps
-br 256000 
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-br 320000 
[/sliderend]
180
0
CBR (Fine) + Correction

8
96 kbps (min)
-br 96000 
97 kbps
-br 97000 
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-br 98000 
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-br 99000 
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-br 100000 
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-br 319000 
320 kbps (max)
-br 320000 
[/sliderend]
85 - out of gas

[checkbox]
30
14
0
 No ID3 v1 Tags
 -noid3v1 


[label]
10
55
<Lossy Quality
808080

[label]
235
55
Lossy Quality>
808080


[clistring]
 -nodbtag -if [infile] -of "[outfile]" -id3in -Title "[title]" -Artist "[artist]" -Album "[album]" -Track [track]

[noallowfloat]

[maxchannels]
2

[estimatesize]
VBR5 ~114 kbps (0.3%>FLAC)
114000
VBR4 ~137 kbps (2.0%>FLAC)
137000
VBR3 ~147 kbps (2.2%>FLAC)
147000
VBR2 ~188 kbps (2.0%>FLAC)
188000
VBR1 ~216 kbps (5.1%>FLAC)
216000
MP3HD help file with switches:

PHP Code:
*****************************************************************************
*                                                                           *
*                                
mp3HD Codec V1.5.0                            *
*                               (
Evaluation Version)                           *
*                                                                              *
*                           (
c2007 2010 Technicolor S.A.                   *
*                          (
c1996 2010 Fraunhofer IIS                      *
*                               
All rights reserved.                           *
*                                                                           *
*       
This software and/or program is protected by copyright law and      *
*        
international treatiesAny reproduction or distribution of        *
*       
this software and/or program, or any portion of itmay result      *
*       
in severe civil and criminal penalties, and will be prosecuted      *
*                 
to the maximum extent possible under law.                 *
*                                                                           *
*****************************************************************************

-----------------------------------------------------------------------------
Origin
-----------------------------------------------------------------------------

Websitehttp://www.all4mp3.com
Contactinfo@all4mp3.com

-----------------------------------------------------------------------------
Software package
-----------------------------------------------------------------------------

This package contains the following software:

mp3HD Command-Line Encoder:   mp3hdEncoder.exe
mp3HD Command-Line Decoder:   mp3hdDecoder.exe
Winamp Decoder Plug-Ins:
  
Winamp 5.5 and above:         in_mp3hd.dll

-----------------------------------------------------------------------------
System requirements
-----------------------------------------------------------------------------

Minimum requirements for the use of the software are:

Windows 2000/Windows XP
At least Pentium III 1 Ghz or higher
At least 128 MB memory
At least 30MB of available hard-disk space
Winamp V5.5 or higher plus stereo soundcard for playback

-----------------------------------------------------------------------------
The mp3HD Format (Some Terminology)
-----------------------------------------------------------------------------

mp3HD is a new scalable format for high-quality lossless compression
of audio signals
.  It guarantees bit-exact reproduction of the
original PCM samples at state
-of-the-art compression ratios.  As for
all lossless compression formatsthe compression ratio and resulting
data rate depends on the compressed content
.  As a rule of thumbthe
mp3HD codec can compress WAV files to about 30
to 60of their
original size 
for typical audio content.  Typicallysmaller data
rates are needed to encode classical music 
or audio books, while Rock
and Pop music requires larger data rates.

mp3HD has been designed with the explicit target to be as compatible
as possible to the ubiquitous MP3 format.  As a consequencethe mp3HD
format uses advanced compression algorithms 
and a special bit stream
format in order to be compatible to most of the available MP3 players
.
Therefore mp3HD is both a lossless format for the reproduction of the
original PCM samples 
and a standard MP3 file that play's on your MP3
player.

The mp3HD Format supports tagging the files with meta data according
to ID3 Version 1.0, 1.1, 2.3 and 2.4. That is, you can use many
existing tools to add ID3 tags to your mp3HD content, and to manage
and organize your audio collection.

-----------------------------------------------------------------------------
mp3HD Command-Line Encoder
-----------------------------------------------------------------------------

This program encodes WAV audio files to mp3HD files.  The WAV audio
files have to contain plain PCM samples in mono or stereo with a
resolution of 16 bit per sample.  The sample rate is restricted to one
out of 32 kHz, 44.1 kHz, or 48 kHz.

It is in the nature of lossless audio compression that the resulting
bit rate is inherently defined by the audio content.  Consequently,
the bit rate of the mp3HD file cannot be specified.  However, the
target bit rate for the backwards-compatible MP3 bit stream already
has to be specified at the time of encoding the mp3HD file.  You can
select both variable bit rate (VBR) mode at several qualities or
constant bit rate (CBR) mode for the resulting MP3 via the
command-line argument "-mode".

For CBR mode you can further define the data rate for the resulting
MP3 file.  The range of possible bit rates is constrained as follows:

  Stereo signals:
   - sample rate of 32   kHz:  80000 - 320000 bit/s
   - sample rate of 44.1 kHz:  96000 - 320000 bit/s
   - sample rate of 48   kHz: 112000 - 320000 bit/s

  Mono signals:
   - sample rate of 32   kHz:  40000 - 320000 bit/s
   - sample rate of 44.1 kHz:  56000 - 320000 bit/s
   - sample rate of 48   kHz:  56000 - 320000 bit/s

To add existing ID3 meta data to the mp3HD file use the command-line 
arguments "-id3in" to pass an existing ID3 (Ver. 2.3 or 2.4) meta data 
file to the mp3HD encoder. For example, the file can be an existing mp3
file that includes the desired ID3 tag information. 

Alternatively, you can use the following command-line arguments to set
the ID3 meta data directly:

   -Title "&*91;title string&*93;" 
   -Artist "&*91;artist string&*93;"  
   -Album "&*91;album string&*93;"
   -Track "&*91;track number&*93;" 
   -Length "&*91;length in ms&*93;"   
   -Year "&*91;year string&*93;"
   -Genre "&*91;content type&*93;" 
   -Encoder "&*91;encoded by ..&*93;"
   -Encoder_Settings "&*91;encoder name and settings&*93;"
   -pic "&*91;jpegFile&*93;"

The "-id3in" command-line argument can'
t be used in combination 
with the other ID3 command
-line arguments.       

To call the mp3HD command-line encoder simply open a command prompt
and enter "mp3hdEncoder".  If called without argumentsthe encoder
outputs a 
list of possible command-line arguments and encoding
options
.

-----------------------------------------------------------------------------
mp3HD Command-Line Decoder
-----------------------------------------------------------------------------

This program decodes mp3 and mp3HD files to WAV audio files.  The output 
files contain bit
-exactly the same PCM samples as the originally encoded 
WAV files
.

Note that the mp3HD decoder cannot reconstruct any side information,
i.eadditional chunks besides the actual audio datathat may have
been contained in the original WAV file
.  Thereforeyou may observe
differences 
if you compare the decoded WAV file with the original WAV
file on the file level
.

To call the command-line decoder simply open a command prompt and
enter "mp3hdDecoder".  If called without argumentsthe decoder
outputs a 
list of possible command-line arguments and decoding
options
.

-----------------------------------------------------------------------------
mp3HD Winamp Decoder
-----------------------------------------------------------------------------

If 
you have a Winamp player installedthe mp3HD format can be added
to the audio formats supported by the player
.  By default, the mp3HD
Winamp Decoder plugin decodes mp3HD files in mp3HD quality
i.ethe
high
-quality original PCM samples are played.

You may configure the plugin to play mp3 quality instead of mp3HD quality
by 
default.  In additionyou can activate in the settings dialog to
display a window in which you can 
switch between mp3 quality and mp3HD
quality in real time 
while decoding an mp3HD file

We recommend to use Winamp version 5.5 or aboveThe new version of 
the Winamp player can be downloaded at http
://www.winamp.com. 

To install the Winamp decoder plug-in copy the "in_mp3hd.dll" file to
your local Winamp plug
-in folderTypicallythe directory of the Winamp 
plug
-in folder is "C:\Program Files\Winamp\plugin".

-----------------------------------------------------------------------------
FAQ
-----------------------------------------------------------------------------

** 
What are PCM samples?

   
The acronym PCM stands for pulse code modulation.  In most digital
   workflows
PCM samples describe the raw digital audio signals
   either right after conversion from the analog domain 
or before
   conversion to the analog domain
.

   
PCM samples are not compressed like e.gMP3 files.  Therefore,
   
they offer in principle the best possible sound quality for a given
   sample rate 
and resolution.  As an examplea CD stores audio as
   
PCM samples with a rate of 44100 samples per second (and channel)
   and 
a resolution of 16 bit per sample.  This gives a bit rate of
   1411.2 kbit
/s.

** 
Can I use the mp3HD Codec to rip my audio CDs?

   
To rip mp3HD files from your audio CDs you need an audio CD 
   grabber tool with external Encoder support
. For example you can use
   
the Exact Audio Copy CD grabberThe current version of Exact Audio 
   Copy can be downloaded at 
   http
://www.exactaudiocopy.de/en/index.php/resources/download/. 
   
   
You can include the mp3HD encoder into the Exact Audio Copy grabber 
   by performing the following steps
:
         
         - 
Open the "Compression options" from the "EAC" menu 
         
Go to the "External Compression" tab
         
Enable the "Use external program for compression" option
         
Set "Parameter passing scheme" to "User Defined Encoder"
         
Write ".mp3" into the "Use file extension" field
         
Type the link to your mp3hdEncoder.exe file into the
           
"Program, including Path, used for compression" field 
         
Insert the following text into the Additional command-line option field:
            -if %
-of %-br %r000 -Artist "%a" -Album "%g" -Title "%t" -Year "%y" 
            
-Track "%n" -Genre "%m" 
         
Select the desired bit rate in the "Bit rate" field.
         - 
Uncheck the "Add ID3 tag" option
   
-----------------------------------------------------------------------------
Version History Release Notes
-----------------------------------------------------------------------------

V1.4.0  First public release of the mp3HD Codec
V1.4.1  First 
public release for Mac OS
        Bug Fix
Winamp pause button didn't work for standard mp3 files
V1.4.2  Command-line argument changes in the mp3hdEncoder
        Minor bug fixes
V1.5.0  Faster En- and Decoding
                Decoding of plain mp3 files
                Original File Length support for plain mp3 files
                Some minor bug fixes
                Encoding of very short input signals
                Automatic resynchronization to the mp3HD stream on errors
                Redesign of the mp3HD Winamp quality switch
                Changed the default ID3 tag version of the mp3HD Encoder to 2.4
                Automatically adds ID3v1 tags to the end of the file

******************************************************************************
*                                                                            *
*                      mp3HD Commandline Encoder v1.5.0                      *
*                         using mp3HD library v1.1.7                         *
*                            (Evaluation Version)                            *
*                                                                            *
*                               Revision 487                                 *
*                              Build Feb  2 2010                             *
*                                                                            *
*                        (c) 2007 - 2010 Technicolor S.A.                    *
*                       (c) 1996 - 2010 Fraunhofer IIS                       *
*                            All rights reserved.                            *
*                                                                            *
*       This software and/or program is protected by copyright law and       *
*         international treaties. Any reproduction or distribution of        *
*        this software and/or program, or any portion of it, may result      *
*       in severe civil and criminal penalties, and will be prosecuted       *
*                 to the maximum extent possible under law.                  *
*                                                                            *
******************************************************************************

Usage: mp3hdEncoder.exe &*91;-if infile&*93; &*91;-of outfile&*93; &*91;-br Birate&*93; &*91;options&*93;

-if infile:
        A 1 channel or 2 channel wave input file.
-of outfile:
        The destination mp3HD bitstream file.

&*91;options&*93;:
-br Bitrate
        The MP3 bitrate in bits/sec <default: 128 Kbit/s>
-mode <0-5>
        Encoder mode (0 = CBR, 1 = VBR highest quality, 5 = VBR lowest
        bit rate) <default: CBR>
        VBR mode 5 is disabled for infiles with 48 kHz samplerate.
-id3in id3File
        The id3File can contain an ID3V1.x and an ID3V2.3 or an ID3V2.4 tag.
        The ID3 tags are copied into the mp3HD file.
        The ID3V2.X tag has to be at the beginning of the file.
        The ID3V1.x tag has to be at the end of the file.
Add ID3 tags directly:
  (Ignored in combination with the "-id3in" option)
        -Title "&*91;title string&*93;"
        -Artist "&*91;artist string&*93;"
        -Album "&*91;album string&*93;"
        -Track "&*91;track number&*93;"
        -Length "&*91;length in ms&*93;"
        -Year "&*91;year string&*93;"
        -Genre "&*91;content type&*93;"
        -Encoder "&*91;encoded by ..&*93;"
        -Encoder_Settings "&*91;encoder name and settings&*93;"
        -pic jpegFile
             The jpegFile must contain an jpeg picture.
             The picture is copied into the mp3HD file.
-noid3v1
        The noid3v1 flag disables the writing of ID3v1 tags.
-com "&*91;Text&*93;"
        Adds a comment text into the mp3HD info frame.
-quiet
        Standard output of only one line

Example:   mp3hdEncoder.exe -br 128000 -if test.wav -of test.mp3