Free mp3 encoder software for windows

The ISO/MPEG Layer III Encoder Library provides a high-level interface for encoding MPEG 1 and MPEG 2 Layer III files.
The following header files are provided for usage in C/C++ programs:
- mp3enc.h: Layer III encoder class definition
- xhead.h: Utility functions to write a TOC header for VBR files
The encoder core resides in a statically linkable library called mp3enc.lib (Microsoft Windows) or mp3enc.a (UNIX). See tomp3.c for an example on how to use the library.
Helix MP3 Encoder is based on the Xing Mp3 Encoder now offered as open souce by RealNetworks, Inc
More about this mp3 encoder HERE

WAV to MP3 Encoder 2.5 serves as an encoder of your ripped WAV files MP3 files. Therefore, you can save your favorite CDs or share them online. This program gives you the option of creating MP3s at 40-bit rates and three sampling rates and in two channels. Batch-convert unlimited WAV files in the fast and easy WinZip-style interface, and preview them before encoding. Also, encode WAV files into custom file sizes for use with portable MP3 players.

ActiveX OCX to encode wav pcm in mp3 files and full ID3 tags support ActiveX OCX programming component that will help you encode wav pcm in mp3 files and full ID3 tags support.
Main features:
- Ability to encode wav pcm files in the mp3 format
- The code is optimized for new processors
- It can encode mp3 files in the following bitrates : 32,40,48,56,64,80,96,112,128,160,192,224,256,320
- Ability to pause resume and cancel the execution
- Full ID3 v1 v1.1 v2 tags support in read and write mode
- Depending on the wav file the encoder can auto change to MPEG2 mode
- It has progress information support
- VBR support
- Three levels of quality encoding method
- Ability to change the priority level of the encoding process
- Stereo modes are : joint stereo , mono , dual channel , stereo

Any command-line MP3 or OGG encoder can be used with the MO3 encoder MO3 is a file format, encapsulating the features of several "MOD" formats (IT, XM, S3M, MTM, MOD), but with one big difference - MP3 and OGG compressed samples. A lossless codec is also incorporated for any samples that dont like lossy encoding, and the whole file structure is compressed too.
All this makes it possible to have great reductions in file sizes with practically identical sound quality. In fact, MO3 allows greater quality compositions because MP3/OGG encoding works best with 16-bit samples, so theres no reason to use low quality 8-bit samples anymore.
Main features:
- MP3/OGG compression
- Any command-line MP3 or OGG encoder can be used with the MO3 encoder
- Lossless compression
- Samples that dont compress well with MP3/OGG encoding can still be reduced in size with the lossless codec
- Structure compression
- All the non-sample data is also compressed
- Sample specific tuning
- The encoding sample/bit rates are individually adjustable for each sample, with visual comparison of original/encoded samples
- Text removal
- Message/instrument/sample texts can optionally be removed for a further size reduction
- Decompressable
- MO3 files can be decoded back to their original formats using UNMO3 (included)
- Playable
- MO3 files can be played by XMPlay and any software that uses the BASS library, also by other software in conjunction with UNMO3

mp3PRO Player/Encoder is a demo player application that supports all bit rates; the encoder is restricted to 64 kbps mp3PRO bit streams.
Main features:
- Encode .wav files into mp3PRO files at 64 kbps.
- Play back all mp3 and mp3PRO files.

Fx Batch Encoder is an application that will help you batch convert/encode video files.