SMPTE ST 361M-2002 Television - NTSC IP and Trigger Binding to VBI.pdf

1、SMPTE 361 M-2002 SMPTE STANDARD for Television - NTSC IP and Trigger Binding to VBI 1 Scope This document defines a standard manner for the carriage of declarative data essence (SMPTE 363M) triggers and IP packets in the vertical blanking interval of the NTSC video standard. Page 1 of 2 pages 3 Intr

2、oduction In NTSC, IP data is broadcast by encoding bytes in the vertical blanking interval of individual video fields. Two different techniques are used for broadcasting data using transport A and transport B as defined in the content level specification (SMPTE 363M). 2 Normative references 4 VBIlin

3、e21 The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to inves

4、tigate the possibility of applying the most recent edition of the standards indicated below. ANSVEIA-516-1988, Joint EIAEVCC Recom- mended Practice for Teletext: North American Basic Teletext Specification (NABTS) EIA-746-A-1988, Transport of Internet Uniform Resource Locator (URL) Information Using

5、 TEXT-2 (T-2) Service EIA/CEA-608-B-2000, Line 21 Data Services IETF RFC 2728, The Transmission of IP Over the Vertical Blanking Interval of a Television Signal SMPTE 170M-1999, Television - Composite Analog Video Signal - NTSC for Studio Applications SMPTE 357M-2002, Television - Declarative Data E

6、ssence - Internet Protocol Multicast Encapsulation SMPTE 363M-2002, Television - Declarative Data Essence - Content Level 1 Triggers are transmitted on VBI line 21 of the NTSC signal using the T-2 service as specified in EIA/CEA-608-B. This encoding is consistent with the EIA-746-A specification whi

7、ch describes how to send URLc and related information on VBI line 21 of an NTSC channel, without interfering with other data (e.g., closed captions) also sent on that line. The checksum described in the DDE trigger definition (SMPTE 363M) is required in the transport A binding to NTSC. Note that, as

8、 specified in the trigger definition, triggers are encoded using ISOAEC 8859-1 (SMPTE 363M) and not the ElA/CEA-608-B character set. (Although most characters are the same in both encodings, a few codes have different meanings.) Trigger length should be kept as short as possible. Trigger transmissio

9、ns should be limited to 25% of the total field 1 bandwidth, even if more bandwidth is available after captioning, to allow for other down- stream services. 5 IPover VBI IP datagrams shall be sent according to IETF RFC 2728. In NTSC, the NABTS (ANSVEIA-516), rather than the WST byte encoding, shall b

10、e used. Copyright O ZW2 by ME SCCIEM OF MOTION PICNRE AND TELEVISION ENGINEERS 5% W. Haitsdale Ave., White Plaina NY 10607 (914) 761-1100 Approved January 3,2002 SMPTE 361 MI-2002 IP streams shall be sent on the NABTS packet addresses Ox4b0 through Ox4bf. Other packet addresses may be used, but receivers are only required to handle IP datagramsarriving using packet addresses x4b0 through x4bf. Annex A (informative) Bibliography ISOAEC 8859-1:1998, InformationTechnology - 8-Bit Single- Byte Coded Graphic Character Sets - Part 1: Latin Alphabet No. 1 Page 2 of 2 pages