The Moving Picture Experts Group

I heard that a Second Edition of MPEG-2 Audio has been approved. What are the reasons behind this revision?

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While implementing the MPEG-2 Audio standard, as published in 1995, it was discovered that a certain combination of functionalities could not function properly. Although this combination was not considered to be of great practical importance, it was felt necessary to correct the standard in this respect. Since this necessitated a revision of the document, the opportunity was then taken to improve the standard in some other fields as well.

The technical changes in the Second Edition compared to the first publication of ISO/IEC 13818-3 (1995) are :

  1. In the first publication, certain combinations of dynamic crosstalk and prediction were not prohibited but not practically implementable. In the Second Edition, these combinations are explicitly prohibited.
  2. In the first publication, a low-pass filter was to be applied to the monophonic surround signal in matrix mode 2 (analogue surround mode). This filter is omitted in the Second Edition, greatly simplifying the decoder and improving coding efficiency.
  3. The description of the syntax of the LFE channel was ambiguous. This description has been clarified.

In addition to these technical changes, many editorial changes have been made, improving readability and clarity.

An amendment concerning copyright registration has been incorporated in the standard.