HD-AAC

Fraunhofer Institute for Digital Media Technology

The new audio format MPEG High Definition AAC (HD-ACC) for lossless storage of audio data is the ideal solution for demanding high-quality audio applications.

  • Audio quality superior to CD (24-bit audio, up to 192 kHz)
  • State-of-the-art lossless compression preserving every bit of information
  • Compatible with many mobile phones and PMPs (i.e. Apple iPod®)
  • Full Metadata support including cover art, ID3 tags and lyrics
  • Based on the ISO MPEG-4 AAC-LC and SLS open standards
  • Maximized sound quality under difficult network conditions
  • High error robustness and boundless editing possibilities

HD-AAC is offered by the Fraunhofer Institute for Integrated Circuits. For further questions about licensing please contact the Fraunhofer IIS.

For several applications in the field of audio processing lossless coding algorithms are required. In cooperation with Fraunhofer IIS the researchers of Fraunhofer IDMT developed lossless codecs that realize an optimal compression ratio and audio quality.

Lossless coding is used where bit-precise and re-constructible coding algorithms are required. This coding algorithm is especially interesting for the professional market e.g. archiving of audio data or the digitalization and storage of old recordings for restoration. Furthermore lossless coding has advantages where cascading effects have negative impact on sound quality.

Such effects are commonplace in complex productions in recording studios or broadcasts where audio signals are encoded and decoded over and over again. Thereby with traditional coding algorithms the audio quality can significantly decrease. Lossless coding algorithms do not show this effect, but as well do not reach the same level of data compression ratio like psycho-acoustical lossy algorithms (e.g. mp3). The available data rates are often highly above of standard audio coders, but not high enough for lossless algorithms, where the data rate depends on the signal.

Among other things the Fraunhofer IDMT participated in the development of algorithms that combine both methods and allow scalability between the MPEG-4 Advanced Audio Coding (AAC) and lossless coding. Thereby the data rate can be optimal adapted on the particular application.

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