ANSI SCTE 243-2 pdf free download
ANSI SCTE 243-2 pdf free download.Next Generation Audio Carriage Constraints For Cable Systems: Part 2 – AC-4 Audio Carriage Constraints.
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 2 131, Section 5.6.2 shall apply when packaging AC- 4 audio into DASH Representations.
6.2.3. Random Access Point and Stream Access Point
To facilitate random access and seamless switches, the constraints defined in ATSC A/342 Part 2 [3], Section 5.6.4 shall apply.
6.2.4. Packaging of Individual Audio Elements
In scenarios where AC-4 DASH Representations from different Adaptation Sets form an AC-4 presentation, the constraints listed in ATSC A/342 Part 2 [3], Section 5.6.5 shall apply.
7. Service Information Signaling
7.1. Signaling of an AC-4 Bitstream in MPEG-2 Transport Streams
7.1.1. AC-4_descriptor
The AC-4_descriptor syntax provides information about individual AC-4 elementary streams within a
Transport Stream that are to be identified in the PSI PMT sections. The AC-4_descriptor is defined in
DVB BlueBook A038 [7], and located in the PMT of the SI Tables that are also defined in DVB
BlueBook A038 [7].The AC-4_ descriptor shall be included in a program map section at most once in each relevant ES_ info descriptor loop which describes an elementary stream carrying an AC-4 audio stream, coded in accordance with ETSI TS 103 190-1 [5]or ETSI TS 103 190-2 [6], that is included in a Transport Stream. 7.1.2. audio_ preselection_ descriptor The audio_ preselection_ _descriptor, specified in DVB BlueBook A038 [7], provides information about the available Audio Preselections for one Audio Program contained in one or more AC-4 Audio associated elementary streams within a Transport Stream that are to be identified in the PSI PMT sections. The contents of the audio_ preselection_ descriptor and the information carried in the AC-4 Audio elementary stream should match as shown in DVB BlueBook A038 [7], table M.1. 7.2. Signaling of an AC-4 Bitstream in ISOBMFF The basic structures defined within ISO/IEC 14496- 12 [8] to identify audio tracks shall be used with specific extensions to provide detailed information on the characteristics of an AC-4 stream. The AC4SampleEntry Box shall be included in the Sample Description Box according to ETSITS 103 190-2 [6] Annex E. The box type of the AC4SampleEntry Box shall be ‘ac-4’.ANSI SCTE 243-2 pdf download.
