The Xing MP3 encoder was created around 1995, seemingly from scratch, by the Xing Technology Corporation with a primary goal in mind: developing a very fast encoder.

And it delivers! It is much faster than other encoders in benchmark tests, even compared to famously fast encoders such as Musepack, Gogo and Ogg Vorbis Lancer. These speed gains are obtained mostly with heavy usage of x86 assembly code (which, in this case, is unfortunately limited to the Windows platform).

Besides creating a super fast encoder (orders of magnitude faster than the competitor at the time, FhG l3enc), Xing were innovators in other areas. Theirs was the first MP3 encoder with a variable bitrate - VBR - mode (released in late 1998. LAME introduced it in June 1999, MPegger in late 1999, and FhG only in 2000). Also, their MPEG encoder was the first and probably the only one that allowed MP3 audio streams in MPEG files - most (all?) other encoders limit them to MP2 streams. They also created audio players, and a CD Ripper based on their encoder, not to mention video encoding, playing and streaming tools which are outside the scope of RRW.

What about quality? Surprisingly, the quality is quite good! Of course not on par with LAME, but if you are in a hurry Xing can be a good choice as it is several times faster.

Xing Technology was acquired by Real Networks in the early 2000s (but you can still check their web site at the Internet Archive) and the MP3 encoder was renamed to Helix MP3 Encoder. Then, in 2005, they released the sources under an open source license. It seems Real closed the sources again, but here you can find compiles of their encoder made while they were still open, as well as the source code.


Date: 2005-07-23
Version: 5.0 (MSVC compile)
Interface: Command line
Platform: Win32
Download: helix_mp3enc_r11_vc7.zip - 113kB

Date: 2005-07-23
Version: 5.0 (ICL compile)
Interface: Command line
Platform: Win32
Download: helix_mp3enc_r11_icl9.zip - 157kB

Date: 2005-07-23
Version: 5.0 (64 bits)
Interface: Command line
Platform: Win64
Download: helix_mp3enc_r11_x64.zip - 156kB

Date: 2005-07-23
Version: 5.0
Interface: Command line
Platform: sources
Download: helix_mp3enc_5.0r11.tar.gz - 230kB

Date: 1999-01-03
Version: 1.5b9
Interface: Graphical
Platform: Win32
Download: MP3EN15.EXE - 1.841kB

Date: 1997-11-03
Version: 3.0
Interface: Command line
Platform: Win32
Download: tompg.zip - 83kB

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Plain MP3 files with VBR encoding have a problem: as they have no header, an MP3 player can not seek into the file or know its duration, unless it decodes the whole file beforehand. CBR files have no such problem because all frames are about the same size, hence it is easy to calculate position and duration.

So Xing came up with a solution: adding a no-audio frame at the beginning of the file which contains a seek table and the track duration. Since it is a valid frame, older MP3 decoders will just skip it and decoders aware of the Xing header can obtain crucial playback information there.

Below you will find Xing's original VBR header SDK. It is worth pointing out that it is forwards-compatible with the LAME header extension.

Date: 1998-12-30
Interface: C SDK
Download: vbrheadersdk.zip - 216kB

FhG later came up with their own VBR header format and, being the usual asshats, made it incompatible with the Xing header:

Date: 2000-11-07
Interface: C++ SDK
Download: mp3_vbr_sdk.zip - 3kB