ANSI SCTE-20-2004 pdf download METHODS FOR CARRIAGE OF CLOSED CAPTIONS AND NON-REAL TIME SAMPLED VIDEO
1. Introduction
1.1 Purpose
This document defines a standard for the carriage of Vertical Blanking Interval (VBI) services in MPEG-2 compliant bitstreams constructed in accordance with ISO/IEC 13818-2 (Reference [1]).
1.2 Revisions
This version is the initial release.
1.3 Scope
The sections in this standard describing video user data extensions to MPEG-2 are organized as follows:
• Section 1—Provides an introduction
• Section 2— Lists normative and informative references
• Section 3—Defines the acronyms and abbreviations used in this specification
• Section 4—Provides an overview of the VBI services supported
• Section 5—Specifies the video bitstream syntax for picture user data extensions
• Section 6—Describes the video bitstream semantics for picture user data extensions
2 References
2.1 Normative References
1. ISO/IEC 13818-2:2000: Information technology — Generic coding of moving pictures and associated audio information – Part 2: Video (MPEG-2 Video)
2. ITU-R BT.601-5, Studio Encoding Parameters of Digital Television for Standard 4:3 and Wide-Screen 16:9 Aspect Ratios, ITU Radiocommunication Assembly, 1995
3. EIA 608-B, Line 21 Data Services, 2000
2.2 Informative References
4. ITU-R BT.470-6, Conventional Television Systems, ITU Radiocommunication Assembly, 1998
3. Acronyms and Abbreviations
bslbf bit string left bit first
CEA Consumer Electronics Association
FCC Federal Communications Commission
IEC International Electrotechnical Commission
ISO International Standards Organization
ITU International Telecommunication Union
LL Low Level
lsb least significant bit
ML Main Level
MP Main Profile
MPEG Moving Picture Experts Group
msb most significant bit
uilsbfopbl unsigned integer least significant bit first odd parity bit last
NTSC National Television System Committee
PAL Phase Alternate Line
uimsbf unsigned integer most significant bit first
VBI Vertical Blanking Interval
VITS Vertical Interval Test Signal
4. Video User Data Extensions The video user data extensions to the MPEG-2 syntax and semantics described in this standard provide a means to support VBI services. This new feature allows carriage and reinsertion of VBI data into the same field from which it originates. The VBI enhancements relative to MPEG-2 main and simple profiles include: a) Closed captioning for single and multiple lines b) Non-real-time sampled video
4.1 Closed Captioning Many television services carry closed caption information in line 21 (field 1 as well as field 2) of the VBI (Reference [3]). The user data syntax described herein supports the carriage and decoder reinsertion of closed captioning information. This feature requires logic to parse, store and reorder closed caption data as well as to synthesize the Federal Communications Commission (FCC) standard closed caption waveform.