Thomson has released software for the creation and playback of a new type of audio file using lossless compression. MP3HD files will be around four times the size of corresponding MP3 files, but will remain compatible with existing MP3 players.
The software includes command-line tools for Windows and Linux that convert standard WAV files into the new MP3HD format, and a plugin for the Winamp media player for Windows PCs for listening to them. The tools can be downloaded from the all4mp3.com Web site run by Thomson, which with German research center Fraunhofer Institute IIS co-developed the MP3 format.
Some people won't be able to hear the difference, but to others, particularly those interested in high-end audio systems, it will be music to their ears.
MP3 files are created using a lossy compression algorithm so some of the audio detail, inaudible to the average listener, is thrown away in the process of compressing and uncompressing the file.
The new format, on the other hand, uses lossless compression, meaning that an MP3HD file made from a WAV audio file will contain all the information required to create a WAV file bit-for-bit identical to the original.
MP3HD files remain compatible with existing MP3 players because they are in fact standard MP3 files. However, rather than throw away the inaudible details during the encoding process, the MP3HD encoder saves them in the ID3 Tag, the part of an MP3 file used to store track details such as album and artist names. Existing MP3 players will read only the standard MP3 information; only MP3HD players will benefit from the additional lossless information stored in the file.
The additional audio information is saved in an unused field of the ID3 tag, and should not be disturbed by software that allows editing of album and artist names, said Thomson's Business Development Director for MP3 and Audio Technology François Thuilière.
Compared to an audio CD, which contains 1411KB of data per second of audio, an MP3HD file will contain between 700K bps (bits per second) and 900K bps of data, according to Thuilière.
"The size of the file will depend on the content, whether its vocals, rock or a symphony," he said.
Most digital music stores sell near-CD-quality tracks encoded at bit rates of between 128K bps and 256K bps.
The MP3 format was a hit because it made it possible to store near-CD-quality audio in about a 10th the space required for the original uncompressed audio file, or to download it in about a 10th the time.
In 2001 Thomson tried to go even further with MP3pro, another variation on MP3 intended to offer the same audio quality with around half the data. However, it didn't catch on because it arrived just as broadband Internet access was starting to take off in Europe and people no longer felt constrained by the speed of dial-up connections.
"Today we're moving in the other direction," said Thuilière.
MP3HD files will be around four times bigger than corresponding MP3 files, he said -- but in an age of 18M bps DSL connections or 100M bps FTTH (fiber to the home) and terabyte hard disc drives, that size should no longer be a problem.
The extensions to the MP3 format contained in MP3HD are proprietary and, as with the original MP3 format, anyone wanting to sell devices containing the encoder or decoder must obtain a license, Thuilière said.