It has been more than two years since the FCC incorporated the ATSC Program and System Information Protocol for Broadcast and Cable (ATSC Standard A/65) into its rules. While many stations have made great strides in complying with the provisions of PSIP, there is still work to be done as Feb. 17, 2009, inches closer.
Since the first version of the PSIP standard was published in 1997, compliance reflected good engineering practice on the part of television stations, since the standard offers benefits for both viewers and broadcasters. PSIP is, in fact, critical to proper operation of the DTV system.
For More InformationThe documents referenced in this article are listed below, along with links to the
ATSC documents are available for download at www.atsc.org/standards.html
- ATSC A/53 Part 4:2007, “MPEG-2 Video System Characteristics”
- ATSC A/65C, “Program and System Information Protocol for Broadcast and Cable, Revision C with Amendment No. 1”
CEA information on acquiring documents can be found at www.ce.org/Standards/
- CEA-608-D, “Line 21 Data Services”
- CEA-708-C, “Digital Television Closed Captioning”
- CEA-766-B, “U.S. and Canadian Region Rating Tables and Content Advisory Descriptors for Transport of Content Advisory Information using ATSC A/65-A Program and System Information Protocol”
SMPTE information on acquiring documents can be found at www.smpte.org/standards
- SMPTE 333M-1999 Television, “DTV Closed-Caption Server to Encoder Interface”
- SMPTE 334-1-2007, “Vertical Ancillary Data Mapping of Caption Data and Other Related Data.”
Information on FCC regulations and guidelines are available at www.fcc.gov.For the viewer, PSIP permits suitably equipped receivers to build an on-screen grid of channels and program information for all DTV services. In addition, the viewer can seamlessly surf from NTSC to HDTV to SDTV. For broadcasters, PSIP maintains local brand identification through the “major channel number.”
PSIP identifies both the DTV channel and the associated NTSC channel and enables DTV receivers to associate the two. In addition, PSIP tells the receiver whether multiple program channels are being broadcast and how to find them. Furthermore, it identifies whether the programs are closed captioned and conveys available v-chip information, among other things.
The FCC mandatory PSIP requirements include the following:
- Master Guide Table, which must have valid linkages to other appropriate tables;
- System Time Table, which must contain time accurate to within one second when sent (each second);
- Virtual Channel Table, which must at least contain the NTSC channel number for each major channel entry, and which the FCC has said they expect to contain accurate Transport Stream ID, service type, modulation mode, source ID and Service Location Descriptor;
- At least the first four Event Information Tables, which must contain the Caption Service Descriptor (when DTV closed captions are present), and the Content Advisory Descriptor (when broadcasters provide such advisories). It is worth noting that the FCC expects broadcasters to send correct program titles to inform consumers about which programs are scheduled to be broadcast.
MORE ABOUT V-CHIP
With a digital-only world approaching, how are program ratings supposed to be carried in HD programming and what should happen with that data in the TV receiver?
Let’s begin with where program rating information is carried in the standards. The short answer is that PSIP is intended to be the primary carrier. However, stations who wish to ensure that legacy receivers that may not understand PSIP (or if they worry about their local cable system) can also place it in the CEA-608 eXtended Data Service as they have traditionally done for SD programming. Doing so might be considered by some as the “belt and suspenders” approach.
PSIP has always provided rating information. It is placed into the Content Advisory Descriptor per the requirements of CEA-766. The Content Advisory Descriptor is carried in the EIT (all types) and may also be placed in the Program Map Table. This descriptor, along with the related Caption Service Descriptor, is extremely important in ensuring the correct delivery of ratings information and closed captions. Broadcasters should verify that their PSIP generator is placing these correctly in their ATSC Transport Stream. Failure to do so is in violation of FCC rules.
Beyond PSIP, program rating is also contained in the CEA-608 XDS data. CEA-608 is carried within CEA-708 captions. HD encoders can be fed CEA-708 captions, typically in one of two ways. The first way is via placement in the vertical ancillary data (VANC) per SMPTE 334-1. (SMPTE has just revised the old SMPTE 334M and published it as SMPTE 334-1—most of the old document was revised—and 334-2—most of which came from the former Chapter 11 of CEA-708-B.)
The second way is via a serial interface per SMPTE 333M. The encoder places the CEA-708 data into the video per the requirements of ATSC A/53 Part 4. Some may consider this a more robust transport than PSIP, since PSIP can be filtered off by cable providers. The FCC has clarified that the cable provider must carry the EIT-0 data, however.
Pat Waddell of Harmonic, who chairs the ATSC Specialist Group on Video/Audio Coding, contributed this section on V-chip.