Program-specific information

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Program-specific information (PSI) is metadata about a program (channel) and part of an MPEG transport stream.

The PSI data as defined by ISO/IEC 13818-1 (MPEG-2 Part 1: Systems) includes four tables:

  • PAT (program association table)
  • CAT (conditional access table)
  • PMT (program map table)
  • NIT (network information table)

PSI is carried in the form of a table structure. Each table structure is broken into sections and can span multiple transport stream packets. Adaptation field also occurs in TS packets carrying PSI data. The PSI data will never be scrambled so that the decoder at the receiving end can easily identify the properties of the stream.

The sections comprising the PAT and CAT tables are associated with predefined PIDs as explained in their respective descriptions below. There may be multiple independent PMT sections in a stream; each section is given a unique user-defined PID and maps a program number to the metadata describing that program and the streams within it. PMT section PIDs are defined in the PAT, and are the only PIDs defined there. The streams themselves are contained in PES packets with user-defined PIDs specified in the PMT.

PSI structure[edit]

Table[edit]

Pointer[1] [2]
Name Number
of bits
Description
Pointer field 8 Present at the start of the packet stream signaled by the payload_unit_start_indicator bit in the TS header. Used to set packet alignment bytes or content before the start of tabled payload data.
Pointer filler bytes N*8 When the pointer field is non-zero, this is the pointer field number of alignment padding bytes set to 0xFF or the end of the previous table (electronic program guide).
Table header[1] [2]
Name Number
of bits
Description
Table ID 8 Table Identifier, that defines the structure of the syntax section and other contained data.
Section syntax indicator 1 A flag that indicates if the syntax section follows the section length. The PAT, PMT, and CAT all set this to 1.
Private bit 1 The PAT, PMT, and CAT all set this to 0. Other tables set this to 1.
Reserved bits 2 Set to 0x03 (all bits on)
Section length unused bits 2 Set to 0 (all bits off)
Section length 10 The number of bytes that follow for the syntax section (with CRC value) and/or table data. These bytes must not exceed a value of 1021.
Syntax section/Table data N*8 When the section length is non-zero, this is the section length number of syntax and data bytes.
Table syntax section
Name Number
of bits
Description
Table ID extension 16 Informational only identifier. The PAT uses this for the transport stream identifier and the PMT uses this for the Program number.
Reserved bits 2 Set to 0x03 (all bits on)
Version number 5 Syntax version number. Incremented when data is changed and wrapped around on overflow for values greater than 32.
Current/next indicator 1 Indicates if data is current in effect or is for future use. If the bit is flagged on, then the data is to be used at the present moment.
Section number 8 This is an index indicating which table this is in a related sequence of tables. The first table starts from 0.
Last section number 8 This indicates which table is the last table in the sequence of tables.
Table data N*8 Data as defined by the Table Identifier.
CRC32 32 A checksum of the entire table excluding the pointer field, pointer filler bytes and the trailing CRC32.

Descriptor[edit]

Descriptor[1] [2]
Name Number
of bits
Description
descriptor tag 8 the tag defines the structure of the contained data following the descriptor length.
descriptor length 8 The number of bytes that are to follow.
Descriptor data N*8 Data as defined by the Descriptor Tag.

PAT (Program association specific data)[edit]

PAT specific data repeated until end of section length
Name Number
of bits
Description
Program num 16 Relates to the Table ID extension in the associated PMT. A value of 0 is reserved for a NIT packet identifier.
Reserved bits 3 Set to 0x07 (all bits on)
Program map PID 13 The packet identifier that contains the associated PMT

The PAT is assigned PID 0x0000 and table id of 0x00. The transport stream contains at least one or more TS packets with PID 0x0000. Some of these consecutive packets form the PAT. At the decoder side the PSI section filter listens to the incoming TS packets. After the filter identifies the PAT table they assemble the packet and decode it. A PAT has information about all the programs contained in the TS. The PAT contains information showing the association of Program Map Table PID and Program Number. The PAT should end with a 32-bit CRC

PMT (Program map specific data)[edit]

PMT specific data
Name Number
of bits
Description
Reserved bits 3 Set to 0x07 (all bits on)
PCR PID 13 The packet identifier that contains the program clock reference used to improve the random access accuracy of the stream's timing that is derived from the program timestamp. If this is unused. then it is set to 0x1FFF (all bits on).
Reserved bits 4 Set to 0x0f (all bits on)
Program info length unused bits 2 Set to 0 (all bits off)
Program info length 10 The number of bytes that follow for the program descriptors.
Program descriptors N*8 When the program info length is non-zero, this is the program info length number of program descriptor bytes.
Elementary stream info data N*8 The streams used in this program map.
Elementary stream specific data repeated until end of section length
Name Number
of bits
Description
stream type 8 This defines the structure of the data contained within the elementary packet identifier.
Reserved bits 3 Set to 0x07 (all bits on)
Elementary PID 13 The packet identifier that contains the stream type data.
Reserved bits 4 Set to 0x0f (all bits on)
ES Info length unused bits 2 Set to 0 (all bits off)
ES Info length length 10 The number of bytes that follow for the elementary stream descriptors.
Elementary stream descriptors N*8 When the ES info length is non-zero, this is the ES info length number of elementary stream descriptor bytes.

This table contains PID numbers of elementary streams associated with the program and it has information about the type of these elementary streams (video, audio, etc.). In addition it may also contain an ECM (entitlement control messages) stream for any other stream that is encrypted. These messages provide the information used in the cipher key selection stage.

CAT (Conditional access specific data)[edit]

This table is used for conditional access management of the cypher keys used for decryption of restricted streams. This table contains privately defined descriptors of the system used and the associated EMM PID. The is used by a network provider to maintain regular key updates. The Table ID value is 0x01.

NIT (network information specific data)[edit]

This optional table may group transport stream identifiers into a network, providing access parameters and other details. ITU-T Rec. H.222 and ISO/IEC 13818-1[1] do not define the NIT structure. The European Broadcasting Union DVB specification ETSI EN 300 468 (DVB-SI)[3] does. The purpose of mentioning but not defining this table in H.222 is that it has reserved program number 0 (zero) in the PAT. The Table ID extension is used to identify the local network together with a directory listing of transport streams. Descriptors are used to list the modulation, source of those streams and programs. The original network identifier is meant to allow transport streams and programs on foreign networks to be included in the local network which allows no remapping of transport and program IDs that may be duplicated between networks. The DVB specification defines the transport packet identifier as 16 and the table identifier of the local network of transports as 64. A table identifier of 65 is for a foreign network of transports. The network identifiers are maintained via DVB Services who have separated the identifiers into two unique, yet unnecessary groupings of Network_ID and Original_Network_ID. The two groupings have a large number of overlapping entries.

PSI labels[edit]

Table Identifiers[edit]

Each table in a transport stream is identified by an 8-bit table identifier.

Identifiers in use
Decimal Hexadecimal Description
0 0x00 Program Association section contains a directory listing of all Program Map Tables
1 0x01 Conditional Access section contains a directory listing of all EMM streams
2 0x02 Program Map section contains a directory listing of all elementary streams.
3 0x03 Transport Stream Description section.
4 0x04 ISO/IEC 14496 scene description section.
5 0x05 ISO/IEC 14496 object description section.
6 0x06 Metadata section.
7 0x07 ISO/IEC 13818-11 IPMP control information (DRM).
8 - 57 0x08 - 0x39 Reserved.
58 0x3A ISO/IEC 13818-6 DSM CC multiprotocol encapsulated.
59 0x3B ISO/IEC 13818-6 DSM CC U-N messages.
60 0x3C ISO/IEC 13818-6 DSM CC Download Data Messages.
61 0x3D ISO/IEC 13818-6 DSM CC stream descriptor list.
62 0x3E ISO/IEC 13818-6 DSM CC privately defined (DVB MAC addressed datagram).
63 0x3F ISO/IEC 13818-6 DSM CC addressable.
64 - 127 0x40 - 0x7F Used by DVB.
128 - 143 0x80 - 0x8F DVB-CSA and DigiCipher II/ATSC CA message sections used in EMM and ECM streams.
144 - 191 0x90 - 0xBF May be assigned as needed to other data tables.
192 - 254 0xC0 - 0xFE Used by DigiCipher II/ATSC/SCTE.
255 0xFF Forbidden. As is used for null padding.

Descriptor Tags[edit]

Each descriptor in a transport stream table is identified by an 8-bit descriptor tag.

Tags in use
Decimal Hexadecimal Description
0 - 1 0x00 - 0x01 Reserved.
2 0x02 Video stream header parameters for ITU-T Rec. H.262, ISO/IEC 13818-2 and ISO/IEC 11172-2
3 0x03 Audio stream header parameters for ISO/IEC 13818-3 and ISO/IEC 11172-3
4 0x04 Hierarchy for stream selection
5 0x05 Registration of private formats
6 0x06 Data stream alignment for packetized video and audio sync point
7 0x07 Target background grid defines total display area size
8 0x08 Video Window defines position in display area
9 0x09 Conditional access system and EMM/ECM PID
10 0x0A ISO 639 language and audio type
11 0x0B System clock external reference
12 0x0C Multiplex buffer utilization bounds
13 0x0D Copyright identification system and reference
14 0x0E Maximum bit rate
15 0x0F Private data indicator
16 0x10 Smoothing buffer
17 0x11 STD video buffer leak control
18 0x12 IBP video I-frame indicator
19 0x13 ISO/IEC13818-6 DSM CC carousel identifier
20 0x14 ISO/IEC13818-6 DSM CC association tag
21 0x15 ISO/IEC13818-6 DSM CC deferred association tag
22 0x16 ISO/IEC13818-6 DSM CC Reserved.
23 0x17 DSM CC NPT reference
24 0x18 DSM CC NPT endpoint
25 0x19 DSM CC stream mode
26 0x1A DSM CC stream event
27 0x1B Video stream header parameters for ISO/IEC 14496-2 (MPEG-4 H.263 based)
28 0x1C Audio stream header parameters for ISO/IEC 14496-3 (MPEG-4 LOAS multi-format framed)
29 0x1D IOD parameters for ISO/IEC 14496-1
30 0x1E SL parameters for ISO/IEC 14496-1
31 0x1F FMC parameters for ISO/IEC 14496-1
32 0x20 External ES identifier for ISO/IEC 14496-1
33 0x21 MuxCode for ISO/IEC 14496-1
34 0x22 FMX Buffer Size for ISO/IEC 14496-1
35 0x23 Multiplex Buffer for ISO/IEC 14496-1
36 0x24 Content labeling for ISO/IEC 14496-1
37 0x25 Metadata pointer
38 0x26 Metadata
39 0x27 Metadata STD
40 0x28 Video stream header parameters for ITU-T Rec. H.264 and ISO/IEC 14496-10
41 0x29 ISO/IEC 13818-11 IPMP (DRM)
42 0x2A Timing and HRD for ITU-T Rec. H.264 and ISO/IEC 14496-10
43 0x2B Audio stream header parameters for ISO/IEC 13818-7 ADTS AAC
44 0x2C FlexMux Timing for ISO/IEC 14496-1
45 0x2D Text stream header parameters for ISO/IEC 14496
46 0x2E Audio extension stream header parameters for ISO/IEC 14496-3 (MPEG-4 LOAS multi-format framed)
47 0x2F Video auxiliary stream header parameters
48 0x30 Video scalable stream header parameters
49 0x31 Video multi stream header parameters
50 0x32 Video stream header parameters for ITU-T Rec. T.802 and ISO/IEC 15444-3 (Motion JPEG 2000)
51 0x33 Video multi operation point stream header parameters
52 0x34 Video stereoscopic (3D) stream header parameters for ITU-T Rec. H.262, ISO/IEC 13818-2 and ISO/IEC 11172-2
53 0x35 Program stereoscopic (3D) information
54 0x36 Video stereoscopic (3D) information
55 - 63 0x37 - 0x3F Reserved.
64 - 127 0x40 - 0x7F Used by DVB.
128 - 207 0x80 - 0xCF Used by ATSC.
208 - 223 0xD0 - 0xDF Used by ISDB.
224 - 233 0xE0 - 0xE9 Used by CableLabs.
234 - 254 0xEA - 0xFE May be assigned as needed to other descriptors.
255 0xFF Forbidden. As is used for null padding.

Elementary stream types[edit]

Each elementary stream in a transport stream is identified by an 8-bit elementary stream type assignment.

Assignments in use
Decimal Hexadecimal Description
0 0x00 Reserved
1 0x01 ISO/IEC 11172-2 (MPEG-1 video)
in a packetized stream
2 0x02 ITU-T Rec. H.262 and ISO/IEC 13818-2 (MPEG-2 higher rate interlaced video)
in a packetized stream
3 0x03 ISO/IEC 11172-3 (MPEG-1 audio)
in a packetized stream
4 0x04 ISO/IEC 13818-3 (MPEG-2 halved sample rate audio)
in a packetized stream
5 0x05 ITU-T Rec. H.222 and ISO/IEC 13818-1 (MPEG-2 tabled data)
privately defined
6 0x06 ITU-T Rec. H.222 and ISO/IEC 13818-1 (MPEG-2 packetized data)
privately defined (i.e., DVB subtitles/VBI and AC-3)
7 0x07 ISO/IEC 13522 (MHEG)
in a packetized stream
8 0x08 ITU-T Rec. H.222 and ISO/IEC 13818-1 DSM CC
in a packetized stream
9 0x09 ITU-T Rec. H.222 and ISO/IEC 13818-1/11172-1 auxiliary data
in a packetized stream
10 0x0A ISO/IEC 13818-6 DSM CC multiprotocol encapsulation
11 0x0B ISO/IEC 13818-6 DSM CC U-N messages
12 0x0C ISO/IEC 13818-6 DSM CC stream descriptors
13 0x0D ISO/IEC 13818-6 DSM CC tabled data
14 0x0E ISO/IEC 13818-1 auxiliary data
in a packetized stream
15 0x0F ISO/IEC 13818-7 ADTS AAC (MPEG-2 lower bit-rate audio)
in a packetized stream
16 0x10 ISO/IEC 14496-2 (MPEG-4 H.263 based video)
in a packetized stream
17 0x11 ISO/IEC 14496-3 (MPEG-4 LOAS multi-format framed audio)
in a packetized stream
18 0x12 ISO/IEC 14496-1 (MPEG-4 FlexMux)
in a packetized stream
19 0x13 ISO/IEC 14496-1 (MPEG-4 FlexMux)
in ISO/IEC 14496 tables
20 0x14 ISO/IEC 13818-6 DSM CC synchronized download protocol
21 0x15 Packetized metadata
22 0x16 Sectioned metadata
23 0x17 ISO/IEC 13818-6 DSM CC Data Carousel metadata
24 0x18 ISO/IEC 13818-6 DSM CC Object Carousel metadata
25 0x19 ISO/IEC 13818-6 Synchronized Download Protocol metadata
26 0x1A ISO/IEC 13818-11 IPMP
27 0x1B ITU-T Rec. H.264 and ISO/IEC 14496-10 (lower bit-rate video)
in a packetized stream
28 - 35 0x1C - 0x23 Reserved.
36 0x24 ITU-T Rec. H.265 and ISO/IEC 23008-2 (Ultra HD video)
in a packetized stream
37 - 65 0x26 - 0x41 Reserved.
66 0x42 Chinese Video Standard
in a packetized stream
67 - 127 0x43 - 0x7F Reserved.
128 0x80 ITU-T Rec. H.262 and ISO/IEC 13818-2 for DigiCipher II
or PCM audio for Blu-ray
in a packetized stream
129 0x81 Dolby Digital up to six channel audio for ATSC and Blu-ray
in a packetized stream
130 0x82 SCTE subtitle
or DTS 6 channel audio for Blu-ray
in a packetized stream
131 0x83 Dolby TrueHD lossless audio for Blu-ray
in a packetized stream
132 0x84 Dolby Digital Plus up to 16 channel audio for Blu-ray
in a packetized stream
133 0x85 DTS 8 channel audio for Blu-ray
in a packetized stream
134 0x86 DTS 8 channel lossless audio for Blu-ray
in a packetized stream
135 0x87 Dolby Digital Plus up to 16 channel audio for ATSC
in a packetized stream
136 - 143 0x88 - 0x8F Privately defined.
144 0x90 Blu-ray Presentation Graphic Stream (subtitling)
in a packetized stream
145 0x95 ATSC DSM CC Network Resources table
146 - 191 0x95 - 0xDF Privately defined.
192 0xC0 DigiCipher II text
in a packetized stream
193 0xC1 Privately defined.
194 0xC2 ATSC DSM CC synchronous data
195 - 208 0xC3 - 0xD0 Privately defined.
209 0xD1 BBC Dirac (Ultra HD video)
in a packetized stream
210 - 233 0xD2 - 0xE9 Privately defined.
234 0xEA Microsoft Windows Media Video 9 (lower bit-rate video)
in a packetized stream
235 - 255 0xEB - 0xFF Privately defined.

References[edit]

  1. ^ a b c d http://www.iso.org/iso/catalogue_detail?csnumber=44169 ISO/IEC 13818-1 Information technology --- Generic coding of moving pictures and associated audio information: Systems (MPEG-2)
  2. ^ a b c http://www.jdsu.com/ProductLiterature/mpeg2_bk_cab_tm_ae.pdf (MPEG-2 Pocketguide)
  3. ^ ETSI-EN 300 468 Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems

External links[edit]