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• Avoids rebranding expense by broadcasters• Provides a basic channel selection method
using an electronic program guide– Simple enough to go in every receiver– Extensible for higher end products– Small change in tuning paradigm for consumer– Compatible with printed media
• Standards documents:– A/52: AC-3 Audio Compression– A/53: ATSC DTV Standard (contains video formats)– A/54: Guide to use of the ATSC DTV Standard– A/55: Program Guide (Optional)– A/56: System Information (Optional)– A/57: Program/Episode/Version Identification– A/58: Harmonization with DVB SI (Rec. Practice)– A/63: Standard for Coding 25/50 Hz Video– A/64: Transmission Measurement & Compliance...– A/65: Program and System Information Protocol…– A/66: PSIP Technical Corrigendum No. 1– A/67: PSIP Technical Amendment No. 1– A/70: Conditional Access System for Terrestrial Broadcast– A/80: Modulation and Coding Reqt’s for DTV Apps. Over Satellite
• PSIP features:– allows navigation and access to each of the channels
within the Transport Stream– preserves channel branding– program guide (from 12 hours to 16 days)– gives the user information for browsing and selection– key system info (e.g., carrier freqs and source ID’s)– rating and content advisory info
• ATSC Receiver can scan active channels forPSIP and can build an integrated guide.
Generic PSIP Table Format• PSIP tables follow format of MPEG-2 Systems “Private Sections”• 9-byte header; N bytes of table data; 4-byte CRC (check sum) trailer• 10+N bytes following section_length field• 13+N bytes total size
Number of GPS seconds since 12 am, 1/6/80Must be accurate to ± 4 sec
DS_status 1 0 = Not in DST; 1 = In DST
5 Day of month in which transition occurs (1-31)reserved 2 ‘11’
descriptors 8*D Descriptor data
7
D
BytesSTT Header 9*8 STT Header9
CRC_32 32 32-bit Cyclic Redundancy Check4
DS_day_of_monthDS_hour 8 Local hour at which transition occurs (0-18)
dayl
ight
savi
ngs
• In order to calculate correct local time, receiver must:– calculate UTC (local time in Greenwich, England)– adjust for local time zone difference– adjust for daylight savings time (if applicable)– convert to date and time format for display
0x0000: TVCT with current_next_indicator=10x0001: TVCT with current_next_indicator=00x0002: CVCT with current_next_indicator=10x0003: CVCT with current_next_indicator=00x0004: Channel ETT0x0100 - 0x017F: EIT-0 to EIT-1270x0200 - 0x027F: Event ETT-0 to Event ETT-1270x0301 - 0x03FF: RRT with rating_region 1-255
3 ‘111’
reserved 3 ‘111’
13
BytesMGT Header 9*8 MGT Header9
CRC_32 32 32-bit Cyclic Redundancy Check4
reservedtable_type_PID 13 PID for table_type in field above
tables_definedfor each table
table_type_version_numbernumber_bytes
5 Must be the same as version number in actual table32 Total number of bytes used for this table4 ‘1111’reserved
descriptors_length 12 Total length (in bytes) of event descriptorsdescriptors 8*D2 Descriptor data
table_type_descriptors_length 12 Total length (in bytes) of event descriptorsdescriptors 8*D1 Descriptor data
Virtual Channel Table (VCT)• Contains list of channels in the Transport Stream.• May also include broadcaster’s analog channel
and digital channels in other Transport Streams.• TVCT = Terrestrial VCT; CVCT = Cable VCT• Key info in VCT:
– short name– major and minor channel numbers– modulation mode and carrier frequency– Transport Stream ID (TSID) and program number– source ID, service type, access controlled and hidden flags– Service Location Descriptor: contains list of PID’s for
Major and Minor Channel Numbers• major_channel_number is used to group all services
associated with a broadcaster’s NTSC brand• minor_channel_number specifies a particular channel
within that group. “0” is reserved for analogservice. All other values (1-999) are allowed fordigital services. One suggestion is to start with 1and to continue numerically.
• A/65, Annex B assigns major_channel_numbers asfollows:– for existing NTSC broadcasters, major_channel_number is
the same as the current NTSC RF channel number (2-69)– for new DTV broadcasters, major_channel_number is the
same as the new DTV RF channel number (2-69)– major_channel_numbers in range 70 - 99 may be used to
identify groups of digital services carried separately
Channel TSID - What and Why?• Channel TSID is a 16-bit number that stands for
– Transport Stream ID (digital)– Transmission Signal ID (analog )
• The receiver may use the Channel TSID to verifythat the Transport Stream acquired at thereferenced carrier frequency is actually the desiredmultiplex.
• Can help resolve co-channel issues and instanceswhere a DTV signal frequency is translatedwithout modification of listed carrier frequency.
• If a broadcaster is transmitting the same signal in differentchannels, each TSID should be unique.
• If a signal is frequency translated without othermodification, then the TSID will remain the same, but thecarrier frequency listed in the VCT will be wrong. In thiscase, receiver should match channel_TSID’s with actualTSID’s to ensure correct presentation.
• A receiver should minimize reliance on carrier frequencieslisted in the VCT. Instead, a receiver should associate theTSID with the carrier frequency at which it is found.
num_events_in_section 8 Number of events in this EIT sectionfor each event:
reserved 2 ‘11’event_id 14 Event ID. Also part of ETM_idstart_time 32 In units of GPS seconds since 12 am, 1/6/80reserved 2 ‘11’
ETM_location 2
00 = No ETM01 = ETM in PTC carrying this PSIP10 = ETM in PTC carrying this event11 = [reserved for future ATSC use]
length_in_seconds 20 Duration of event in secondstitle_length 8 Length (in bytes) of title_texttitle_text 8*T Event title (multiple string structure format)reserved 4 ‘1111’descriptors_length 12 Total length (in bytes) of event descriptorsdescriptors 8*D Descriptor data
• Source ID’s link events to virtual channels. 0x0001 - 0x0FFF areunique within this Transport Stream; 0x1000 - 0xFFFF areunique at the regional level.
• Event ID’s are unique within this Transport Stream.
• The RRT defines the rating standard for a particulargeographic region and/or country
• Each RRT instance is identified by the rating_region field in thetable_id_extension
• Only one rating region is currently defined: “US (50 states +possessions)”
• The Content Advisory Descriptor, which may appear in theEIT and PMT, indicates, for a given event, the ratings for anyor all of the rating dimensions defined in the RRT.
• Full implementation in the U.S. requires document EIA-766:“U.S. Region Rating Table (RRT) and Content Advisory Descriptor for Transportof Content Advisory Information Using ATSC A/65 Program and SystemInformation Protocol (PSIP)”, September 1998.
RRT Information for U.S.• To date, the U.S. is the only rating region that has been defined• This is documented in EIA-766, Sept. 1998 and summarized below
and in the following slides:
Syntax Element Valuerating_region 0x01version_number 00000rating_region_name_text() US (50 states + possessions)dimensions_defined 0x08
Text Formatting ValueISO_639_language_code 0x656E67compression_type 0x00mode 0x00number_strings 0x01number_segments 0x01
rating_region_name_text = “US (50 states + possessions)”
dimension_name = “MPAA”; dimension index = 7; grad = “0”
index abbrev value0 “ ” “ ”1 “N/A” “MPAA Rating Not Applicable”2 “G” “Suitable for All Ages”3 “PG” “Parental Guidance Suggested”4 “PG-13” “Parents Strongly Cautioned”5 “R” “Restricted, under 17 must be accompanied by adult”6 “NC-17” “No One 17 and Under Admitted”7 “X” “No One 17 and Under Admitted”8 “NR” “Not Rated by MPAA”
* * * * * * *AC-3 audio 0x81 M M Ocaption service 0x86 M M Ocontent advisory 0x87 M M O
extended channel name 0xA0 M Mservice location 0xA1 S Mtime-shifted service 0xA2 M Mcomponent name 0xA3 M
user private *0xC0-0xFE * * * * * * *
Legend*MOS
descriptor may appear without restrictionswhen present, descriptor must appear in location shownwhen present, descriptor may optionally appear in second location shownthe service location descriptor must be present in the location shown
7 Length of text field that follows1 1 = ISO Latin-1; 0 = 16-bit Unicode
8*T Brief description of audio servicetext
3 Sample rate of encoded audiosample_rate_code
elseasvcflags 8 Links main and associated services
bit_rate_code 6 Indicates bit rate (exact or upper limit)surround_mode 2 Same as dsurmod field in AC-3 streambsmod 3 Same as bsmod field in AC-3 streamnum_channels 4 Indicates audio coding or number of channelsfull_svc 1 Indicates full or partial audio servicelangcod 8 Same as langcod field in AC-3 stream
8*A Additional description (not currently defined)additional_info
Content Advisory Information for U.S.• To date, the U.S. is the only rating region that has been defined• This is documented in EIA-766, Sept. 1998 and summarized below
and in the following slides:
Syntax Element Valuerating_region 0x01rated_dimensions [0x01, 0x08] (program specific)rating_dimension [0x00, 0x07] (signifies dimension)rating_value Index into Rating Message Tablerating_description_length 0x00rating_description_text None
Time Shifted Service DescriptorSyntax Bits Format or Note
8
number_of_servcies 5 Number of time-shifted services (1-20)
Number of bytes following this field
time_shift 10 Number of minutes this service is shifted (1-720)5
Bytesdescriptor_tag 8 0xA22descriptor_length
for each service
major_channel_number
reserved
10 Major channel number (1-99) of time shifted service
6 ‘111111’
3 ‘111’reserved 1
reserved 4 ‘1111’
minor_channel_number 10 Minor channel number (0-999) of time shifted service
This descriptor can be used for Near Video On Demand (NVOD) services,in which the same event is repeated, usually at regular intervals, on differentvirtual channels.
• PSIP tables can start at any byte in a Transport Packetexcept for MGT, whose first byte must be the first payloadbyte. For MGT packets carrying the table_id field:– payload_unit_start_indicator = 1– pointer_field = 0x00.
• Table sections may span packet boundaries.• More than one PSIP table may be present within a single
Transport Packet.– pointer_field used to indicate offset of first table header– subsequent table locations found by section_length fields
• If packet payload does not include start of any PSIP table:– payload_unit_start_indicator = 0– pointer_field not present
– “Amendment No. 1 to ATSC Standard: Program and SystemInformation Protocol for Terrestrial Broadcast and CableDoc. A/65 (23 Dec 97)”, ATSC Document A/67, 17 Dec 99.
– Provides a means to deal with currently inactive channels– Available at www.atsc.org
• Conditional Access System for Terrestrial B’cast (A/70)– Defines ATSC_CA_descriptor for VCT and EIT
• “U.S. Region Rating Table (RRT) and Content AdvisoryDescriptor for Transport of Content Advisory InformationUsing ATSC A/65 Program and System InformationProtocol (PSIP)”, September 1998 (EIA-766)– Used for rating and content advisory in the U.S.
Data Event Table Format (draft)Syntax of DET Table Bits Format or Note
num_data_in_section 8 Number of events in this DET sectionfor each data:
reserved 2 ‘11’data_id 14 Data ID. Also part of ETM_idstart_time 32 In units of GPS seconds since 12 am, 1/6/80reserved 2 ‘11’
ETM_location 2
00 = No ETM01 = ETM in PTC carrying this PSIP10 = ETM in PTC carrying this event11 = [reserved for future ATSC use]
length_in_seconds 20 Duration of data in sec (unbounded = 0xFFFFF)title_length 8 Length (in bytes) of title_text (0 = no title)title_text 8*T Data title (multiple string structure format)reserved 4 ‘1111’descriptors_length 12 Total length (in bytes) of data descriptorsdescriptors 8*D Descriptor data
Note: a Data Service Descriptor is required for every data event
0x00: reserved0x01: ATSC Data Bcast Service Profile G10x02: ATSC Data Bcast Service Profile G20x03: ATSC Data Bcast Service Profile G20x04: ATSC Data Bcast Service Profile A10x05-0xFF: ATSC reserved
8data_service_level 1
0x00: no synchronized stream in service0x01: Data Service Level 1 (DBESn = 120120 B)0x02-0x03: ATSC reserved0x04: Data Service Level 4 (DBESn = 480480 B)0x05-0x0F: ATSC reserved0x10: Data Service Level 16 (DBESn = 1921920 B)0x11-0x3F: ATSC reserved0x40: Data Service Level 64 (DBESn = 7687680 B)0x41-0xFF: ATSC reserved
private_data_length 8 Length in bytes of field that followsfor each byte
PID Count Descriptor (draft)Syntax Bits Format or Note
8 Number of bytes following this field
Bytesdescriptor_tag 8 0xA52descriptor_length
3 ‘111’reserved
2
This optional descriptor can help the receiver determine resources requiredfor PID handling.
13Max number of concurrent PID’s for thedata services. Shall include PID’s for DataService Table and Network Resources Table
total_number_of_PIDs
3 ‘111’reserved
2 13
Minimum number of PID’s that a receiver mustacquire simultaneously to provide a meaning-ful rendition of the service. 0 means theminimum number is unspecified.
This is a special Data Event Table that can announce data services beyond thecurrently defined time period (far into the future).
Syntax of LTST Table Bits Format or Note
num_data_in_section 8 Number of events in this DET sectionfor each data:
reserved 1 ‘1’AV_association_flag 1 1 means the data is associated with AV event
start_time 32 In units of GPS seconds since 12 am, 1/6/80length_in_seconds 16 Duration of data in sec (unbounded = 0xFFFFF)
title_length 8 Length (in bytes) of title_text (0 = no title)title_text 8*T Data title (multiple string structure format)reserved 4 ‘1111’descriptors_length 12 Total length (in bytes) of data descriptorsdescriptors 8*D Descriptor data
– PSIP Ad Hoc Group (Art Allison, chair)– Directed Channel Change: Provides a means to enable
directed channel change, either by direct viewer selection orautomatically (Merrill Weiss, chair)
– Extensions to Accommodate Non-Alphabetic Characters:needed to support PSIP in other ATSC countries, such asKorea and Taiwan. Draft Recommended Practice has beenprepared. (Chao Yang, chair)
– Advanced EPG Functionality: Looking at content-baseddescription of events to allow improved browsing (RegisCrinon and Paul Martinez, chairs)
Relevant Committee Work (cont’d)• Other Topics (closed):
– GPS Time Annex– NVOD clarification– ETT table_id_extension– Unicode issues– Clarify events that cannot overlap– Correct private indicator bit in Table 4.1
• Other Topics (still open)– VCT scaling– Transmission of VCT’s with different branding (cable/air)– Private descriptors– Single-part channel numbers (cable)– Version management of shifting EIT’s– Clarify situations where analog pointer is to be believed