ANSI SCTE 243-2-2017 pdf download.Next Generation Audio Carriage Constraints For Cable Systems
1.1. Scope
This document is part of a three-part standard that specifies carriage constraints of Next Generation Audio (NGA) codecs in MPEG-2 transport systems and in MPEG DASH. In conjunction with SCTE 243-1 2017 [2], this document defines the carriage of AC-4 audio in MPEG-2 transport systems and MPEG DASH.
2. Normative References
The following documents contain provisions, which, through reference in this text, constitute provisions of this document. At the time of Subcommittee approval, the editions indicated were valid. All documents are subject to revision; and while parties to any agreement based on this document are encouraged to investigate the possibility of applying the most recent editions of the documents listed below, they are reminded that newer editions of those documents might not be compatible with the referenced version.
4. Compliance Notation
shall This word or the adjective “required” means that the item is an absolute requirement of this document. shall not This phrase means that the item is an absolute prohibition of this document. forbidden This word means the value specified shall never be used. should This word or the adjective “recommended” means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighted before choosing a different course. should not This phrase means that there may exist valid reasons in particular circumstances when the listed behavior is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behavior described with this label. may This word or the adjective “optional” means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item. deprecated Use is permissible for legacy purposes only. Deprecated features may be removed from future versions of this document. Implementations should avoid use of deprecated features.
6.1.2. PES Packaging
Placement of raw AC-4 frames of an AC-4 Elementary Stream (ES) into Packetized Elementary Stream (PES) and thence into Transport Stream (TS) packets shall be done in accordance with ETSI TS 101 154 [4], Section 6.6.2.
6.1.3. Audio/Video
Synchronization AC-4 can encode audio at the same frame rate as the accompanying video to facilitate keeping audio and video in sync throughout the distribution chain. When this feature is enabled, the AC-4 audio elementary stream shall comply with the constraints defined in ETSI TS 101 154 [4], Section 6.6.6.
6.2. ISOBMFF Packaging for Carriage in MPEG DASH
This section describes the packaging rules for AC-4 compressed audio carried in the ISO Base Media File Format (ISOBMFF) for transport in MPEG DASH.
6.2.1. Packaging of AC-4 Bitstreams into ISOBMFF Segments Each raw AC-4 frame shall be packaged as an ISO Base Media File Format sample. For more information, refer to ETSI TS 103 190-2 [6], Annex E.3. AC-4 sync frames as described in ETSI TS 103 190-2 [6], Annex C, shall not be packetized directly into ISO Base Media File Format.
6.2.2. Additional Constraints on AC-4 Elementary Streams ETSI TS 103 190-2 [6], Annex E, describes the constraints that shall be applied to the AC-4 bitstream for storage within the ISO base media file format. For the use of DASH with the ISO base media file format, the additional constraints listed in ATSC A/342 Part 2 [3], Section 5.6.2 shall apply when packaging AC- 4 audio into DASH Representations.ANSI SCTE 243-2-2017 pdf download
