MP3 HD: Even if AAC is becoming more and more popular, there are still enough friends of the MP3. In March 2009, Thomson introduced a backward compatible lossless MP3 extension that enables data reduction by up to 70%. As with the modern ISO standard AAC SLS (Scalable to Lossless), a development of the Institute for Infocomm Research (I2R) and Fraunhofer IIS, an MP3HD file contains a lossy coded core - in this case, of course, in MP3 format - and in addition the losslessly encoded content; the MP3HD bitstream should differ from any conventional MP3Decoder play lossy. All MP3 tools should also be able to handle the HD files. You only need an MP3HD decoder for lossless playback.
