scope:

The present document specifies an extension to the E-AC-3 codec.

The extension adds an object-based three-dimensional spatial representation of coded audio information and metadata. It is backward compatible with the one- and two-dimensional channel-based spatial representation of coded audio information as defined in ETSI TS 102 366 [1].

NOTE: In this context, backward compatibility is defined as follows: The three-dimensional spatial representation specified in the present document can be decoded on a device compliant with the syntax and semantics specified in ETSI TS 102 366 [1]. In this case, such a device will output one- or two-dimensional channel-based audio as per the coding algorithm defined in ETSI TS 102 366 [1] alone. Thus, support for decoders specified in ETSI TS 102 366 [1] and associated user experiences are fully maintained with the extension defined herein.

The present document specifies the following:

1) Syntax and semantics of the OBA metadata, carried via the extensible metadata delivery format (EMDF), specified in ETSI TS 102 366 [1]

2) Syntax and semantics of metadata to control a tool for conversion of one- or two-dimensional channel-based audio to a higher number of audio signals, part of the three-dimensional spatial representation (JOC)

3) Additional requirements on the E-AC-3 decoder as specified in ETSI TS 102 366 [1]

4) Requirements on the OBA, the JOC tool, the quadrature mirror filter bank tool, packaging the bitstream into ISO based media file format, the signalling in an MPEG DASH media presentation description, and requirements on a MPEG CMAF compliant media file, containing a bitstream as defined in the present document.

5) Informative guidance for conversion from 1) to the ADM as defined in Recommendation ITU-R BS.2076 [i.1]