BS ISO IEC 23001-8 pdf download.Information technology — MPEG systems technologies
1 Scope
of ISO/IEC 23001 defines various code points and fields that establish properties of a video or audio stream that are independent of the compression encoding and bit rate. These properties may describe the appropriate interpretation of decoded video or audio data or may, similarly, describe the characteristics of such signals before the signal is compressed by an encoder that is suitable for compressing such an input signal.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 11664-1, Colorimetry — Part 1: CIE standard colorimetric observers Rec. ITU-R BS.1770, Algorithms to measure audio programme loudness and true-peak audio level Rec. ITU-R BS.1771-1, Requirements for loudness and true-peak indicating meters EBU R 128, Loudness normalization and permitted maximum level of audio signals EBU Tech 3341, Loudness Metering: EBU mode metering to supplement loudness normalization in accordance with EBU R128 EBU Tech 3342, Loudness Range: A measure to supplement loudness normalisation in accordance with EBU R 128
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1.1 channel Ch. conceptual representation of an audio signal for coding or transmission as it may be used within the digital signal processing chain of an audio codec Note 1 to entry: A channel may correspond directly to one specific loudspeaker or it may carry an audio signal that is meant to be further processed and played back on more than one loudspeaker by some means not further specified here. 3.1.2 DRC dynamic range compressor process that modifies the amplitude of an audio signal 3.1.3 K-weighted frequency weighting by means of a two-stage filter, as defined in Rec. ITU-R BS.1770 3.1.4 LKFS loudness, K-weighted, relative to nominal full scale, as defined in Rec. ITU-R BS.1770 3.1.5 loudspeaker LS physical loudspeaker with a given geometric position relative to the listener and, if applicable, a label or name Note 1 to entry: Even though the loudspeaker names used in this part of ISO/IEC 23001 each describe one discrete loudspeaker position, some loudspeaker signals may, in practice, be rendered on a loudspeaker array consisting of multiple loudspeakers which are all driven with the same audio signal, for example, in a theatrical setting. 3.1.6 loudspeaker index association of a loudspeaker geometric position to a given index 3.1.7 loudspeaker layout set of loudspeakers with a specific constellation of geometric positions meant for authoring or play- back of audio content 3.1.8 loudspeaker layout index association of a loudspeaker layout to a given index 3.2 Abbreviated terms For the purposes of this document, the following abbreviated terms apply. LSB least-significant bit MSB most-significant bit
5 Introduction
5.1 General This Clause identifies the code points defined in this part of ISO/IEC 23001, as listed in Table 1 with cross-references to the subclause in which each is specified.5.2 Background In a number of specifications, there is a need to identify some characteristics of media that are logically independent of the compression format (for example, aspects that relate to the sourcing or presentation or the role of the media component). These media characteristics have typically been documented by fields that take an encoded value or item selected from an enumerated list, herein called code points. These code points are typically defined in the specification of compression formats to document these characteristics of the media. In past practices, the definition of these fields has been copied from standard to standard, sometimes with new values being added in later standards (and sometimes with later amendments specified to add new entries to existing standards). This past practice has raised a number of issues, including the following: a) A lack of a formal way to avoid conflicting assignments being made in different standards. b) Having additional values defined in later specifications that may be practically used with older compression formats, but without clear formal applicability of these new values to older standards. c) Any update or correction of code point semantics can incur significant effort to update all standards in which the code point is specified, instead of enabling a single central specification to apply across different referencing specifications. d) The choice of reference for other specifications (such as container or delivery formats) not being obvious; wherein a formal reference to a compression format standard appears to favour that oneformat over others, and also appears to preclude definitions defined in other compression format specifications. e) Burdensome maintenance needs to ensure that a reference to material defined in a compression format specification is maintained appropriately over different revisions of the referenced format specification, as the content of a compression format specification may change over time and is ordinarily not intended as a point of reference for defining such code points. This part of ISO/IEC 23001 provides a central definition of such code points to address these issues.
BS ISO IEC 23001-8 pdf download
