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Analysis/Synthesis Audio Coding (MPEG-4 HILN Parametric Audio Coding)

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Standardization activities within MPEG-4 have been started which aim at the developement of a coding standard for transmitting audio signals at bit rates below 16 kbit/s.

Currently available general purpose audio codecs operate at bit rates above 16 kbit/s. On the other hand speech codecs operating in the desired range of bit rates are not suited for encoding audio signals.

A coding scheme is to be developed wich allows the transmission of audio signals with a bandwidth of 4 ... 8 kHz at bit rates between 6 and 16 kbit/s.

The concept of an object based analysis/synthesis scheme is applied.

In the encoder the input signal is first decomposed into audio objects which can be described by appropriate source models and represented by corresponding sets of model parameters. For each object the model parameters are estimated, coded, and transmitted. Additionally a signal is synthesized from the derived parameters which assists the decomposition of the residual. Quantization and coding of the model parameters is controlled by a psychoacoustic model which exploits the input signal dependent sensitivity of the human ear to reconstruction errors.

In the decoder for each audio object a signal is synthesized from the decoded model parameters. The decoder output is the sum of all object signals.

This coding scheme was adopted as parametric audio coder in the MPEG-4 Audio Standard, where it is referred to as HILN ("Harmonic and Individual Lines plus Noise").

Further details about this coding scheme are available from numerous publications. For general information, see the Parametric Audio Coding Bibliography.

Show recent publications only
  • Journals
    • Nicolle van Schijndel, Julien Bensa, Mads Christensen, Catherine Colomes, Bernd Edler, Richard Heusdens, Jesper Jensen, Jensen Søren, Bastiaan Kleijn, Valery Kot, Balazs Kovesi, Jonas Lindblom, Dominique Massaloux, Omar Niamut, Frederik Norden, Jan Plasberg, Renat Vafin, Steven van de Par, David Virette, Oliver Wübbolt
      Adaptive RD Optimized Hybrid Sound Coding
      J. Audio Eng. Soc., Audio Engineering Society, Vol. 56, No. 10, pp. 787-809, October 2008
    • Bernd Edler
      Audiocodierung in MPEG-4
      Telekommunikation Aktuell, Verlag für Wissenschaft und Leben, Erlangen, July 2004
    • Laura Contin, Bernd Edler, David Meares, Pete Schreiner
      Tests on MPEG-4 Audio Codec Proposals
      Signal Processing: Image Communication, Vol. 9, No. 4, pp. 327-342, May 1997
  • Conference Contributions
    • Heiko Purnhagen, Nikolaus Meine, Bernd Edler
      Sinusoidal Coding Using Loudness-Based Component Selection
      Int. Conf. on Acoustics, Speech, and Signal Processing, Orlando, May 2002
    • Heiko Purnhagen, Bernd Edler, Nikolaus Meine
      Error Protection and Concealment for HILN MPEG-4 Parametric Audio Coding
      110th AES Convention, Audio Engineering Society, p. Preprint 5300, Amsterdam, May 2001
    • Frank Baumgarte, Bernd Edler
      Ein Psychophysiologisches Gehörmodell zur Nachbildung von Wahrnehmungsschwellen für die Audiocodierung
      DFG-Abschlußkolloquium, München, October 2000
    • Heiko Purnhagen, Nikolaus Meine, Bernd Edler
      Speeding up HILN - MPEG-4 Parametric Audio Encoding with Reduced Complexity
      109th AES Convention, Audio Engineering Society, p. Preprint 5177, Los Angeles, September 2000
    • Bernd Edler, Heiko Purnhagen
      Parametric Audio Coding
      5th International Conference on Signal Processing (ICSP 2000), Beijing, August 2000
    • Bernd Edler, Heiko Purnhagen
      Concepts for Hybrid Audio Coding Schemes Based on Parametric Techniques
      105th AES Convention, Audio Engineering Society, p. Preprint 4808, San Francisco, September 1998
    • Heiko Purnhagen, Bernd Edler, Charalampos Ferekidis
      Object-Based Analysis/Synthesis Audio Coder for Very Low Bit Rates
      104th AES Convention, Audio Engineering Society, p. Preprint 4747, Amsterdam, May 1998
    • Heiko Purnhagen, Bernd Edler
      Objektbasierter Analyse/Synthese Audio Coder für sehr niedrige Datenraten
      ITG-Fachtagung "Codierung für Quelle, Kanal und Übertragung", Aachen, March 1998
    • Bernd Edler
      Very Low Bit Rate Audio Coding Developement
      14th International AES Conference "internet.aes.org", Seattle, June 1997
    • Bernd Edler
      Overview on the Current Development of MPEG-4 Audio Coding
      4th International Workshop on Systems, Signals and Image Processing, Poznan, May 1997
    • Bernd Edler
      Current Status of the MPEG-4 Audio Verification Model Development
      101th AES Convention, Audio Engineering Society, p. Preprint 4376, Los Angeles, November 1996
    • Bernd Edler, Heiko Purnhagen, Charalampos Ferekidis
      ASAC - Analysis/Synthesis Audio Codec for Very Low Bit Rates
      100th AES Convention, Audio Engineering Society, p. Preprint 4179, Copenhagen, May 1996