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2.4.4 Program specific information

Program Specific Information (PSI) includes both ITU T Rec. H.222.0†|†ISO/IEC 13818-1 normative data and private data that enable de-multiplexing of programs by decoders. Programs are composed of one or more elementary streams, each labeled with a PID. Programs, elementary streams or parts thereof may be scrambled for conditional access. However, Program Specific Information shall not be scrambled.

In Transport Streams, Program Specific Information is classified into four table structures as shown in the table below. While these structures may be thought of as simple tables, they shall be segmented into sections and inserted in Transport Stream packets, some with predetermined PIDs and others with user selectable PIDs.

Table 2-23 -- Program specific information Structure Name	Stream Type	PID number	Description
Program Association Table	ITU T Rec. H.222.0†\|†ISO/IEC 13818-1	0x00	Associates Program Number and Program Map Table PID
Program Map Table	ITU T Rec. H.222.0†\|†ISO/IEC 13818-1	Assignment indicated in the PAT	Specifies PID values for components of one or more programs
Conditional Access Table	ITU T Rec. H.222.0†\|†ISO/IEC 13818-1	0x01	Associates one or more (private) EMM streams each with a unique PID value

ITU T Rec. H.222.0†|†ISO/IEC 13818-1 defined PSI tables shall be segmented into one or more sections that are carried within transports packets. A section is a syntactic structure that shall be used for mapping each ITU T Rec. H.222.0†|†ISO/IEC 13818-1-defined PSI table into Transport Stream packets.

Along with ITU T Rec. H.222.0†|†ISO/IEC 13818-1-defined PSI tables, it is possible to carry private data tables. The means by which private information is carried within Transport Stream packets is not defined by this Specification. It may be structured in the same manner used for carrying of ITU T Rec. H.222.0†|†ISO/IEC 13818-1-defined PSI tables, such that the syntax for mapping this private data is identical to that used for the mapping of ITU T Rec. H.222.0†|†ISO/IEC 13818-1-defined PSI tables. For this purpose, a private section is defined. If the private data is carried in Transport Stream packets with the same PID value as Transport Stream packets carrying Program Map Tables, (as identified in the Program Association Table), then the private_section syntax and semantics shall be used. The data carried in the private_data_bytes may be scrambled. However, no other fields of the private_section shall be scrambled. This private_section allows data to be transmitted with a minimum of structure. When this structure is not used, the mapping of private data within Transport Stream packets is not defined by ITU T Rec. H.222.0†|†ISO/IEC 13818-1.
Sections may be variable in length. The beginning of a section is indicated by a pointer_field in the Transport Stream packet payload. The syntax of this field is specified in table 2-24 on page 46.
Adaptation fields may occur in Transport Stream packets carrying PSI sections.
Within a Transport Stream, packet stuffing bytes of value 0xFF may be found after the last byte of a section, in which case all following bytes until the end of the Transport Stream packet shall also be stuffing bytes of value 0xFF. These bytes may be discarded by a decoder. In such a case, the payload of the next Transport Stream packet with the same PID value shall begin with a pointer_field of value 0x00 indicating that the next section starts immediately thereafter.
Each Transport Stream shall contain one or more Transport Stream packets with PID value 0x0000. These Transport Stream packets together shall contain a complete Program Association Table, providing a complete list of all programs within the Transport Stream. The most recently transmitted version of the table with the current_next_indicator set to a value of '1' shall always apply to the current data in the Transport Stream. Any changes in the programs carried within the Transport Stream shall be described in an updated version of the Program Association Table carried in Transport Stream packets with PID value 0x0000. These sections shall all use table_id value 0x00. Only sections with this value of table_id are permitted within Transport Stream packets with PID value of 0x0000. For a new version of the PAT to become valid, all sections (as indicated in the last_section_number) with a new version_number and with the current_next_indicator set to '1' must exit B_sys defined in the T-STD (refer to 2.4.2 on page 11). The PAT becomes valid when the last byte of the section needed to complete the table exits B_sys.
Whenever one or more elementary streams within a Transport Stream are scrambled, Transport Stream packets with a PID value 0x0001 shall be transmitted containing a complete Conditional Access Table including CA_descriptors associated with the scrambled streams. The transmitted Transport Stream packets shall together form one complete version of the conditional access table. The most recently transmitted version of the table with the current_next_indicator set to a value of '1' shall always apply to the current data in the Transport Stream. Any changes in scrambling making the existing table invalid or incomplete shall be described in an updated version of the conditional access table. These sections shall all use table_id value 0x01. Only sections with this table_id value are permitted within Transport Stream packets with a PID value of 0x0001. For a new version of the CAT to become valid, all sections (as indicated in the last_section_number) with a new version_number and with the current_next_indicator set to '1' must exit B_sys. The CAT becomes valid when the last byte of the section needed to complete the table exits B_sys.
Each Transport Stream shall contain one or more Transport Stream packets with PID values which are labeled under the program association table as Transport Stream packets containing TS program map sections. Each program listed in the Program Association Table shall be described in a unique TS_program_map_section. Every program shall be fully defined within the Transport Stream itself. Private data which has an associated elementary_PID field in the appropriate Program Map Table section is part of the program. Other private data may exist in the Transport Stream without being listed in the Program Map Table section. The most recently transmitted version of the TS_program_map_section with the current_next_indicator set to a value of '1' shall always apply to the current data within the Transport Stream. Any changes in the definition of any of the programs carried within the Transport Stream shall be described in an updated version of the corresponding section of the program map table carried in Transport Stream packets with the PID value identified as the program_map_PID for that specific program. All Transport Stream packets which carry a given TS_program_map_section shall have the same PID value. During the continuous existence of a program, including all of its associated events, the program_map_PID shall not change. A program definition shall not span more than one TS_program_map_section. A new version of a TS_program_map_section becomes valid when the last byte of that section with a new version_number and with the current_next_indicator set to '1' exits B_sys.
Sections with a table_id value of 0x02 shall contain Program Map Table information. Such sections may be carried in Transport Stream packets with different PID values.
The Network Information Table is optional and its contents are private. If present it is carried within Transport Stream packets that shall have the same PID value, called the network_PID. The network_PID value is defined by the user and, when present, shall be found in the Program Association Table under the reserved program_number 0x0000. If the network information table exists, it shall take the form of one or more private_sections.
The maximum number of bytes in a section of a ITU T Rec. H.222.0†|†ISO/IEC 13818-1-defined PSI table is 1 024 bytes. The maximum number of bytes in a private_section is 4 096 bytes.
There are no restrictions on the occurrence of start codes, sync bytes or other bit patterns in PSI data, whether ITU T Rec. H.222.0†|†ISO/IEC 13818-1 or private.

2.4.4.1 Pointer

The pointer_field syntax is defined in table 2-24 below.

Table 2-24 -- Program specific information pointer Syntax	No. of bits	Mnemonic
pointer_field	8	uimsbf

2.4.4.2 Semantics definition of fields in pointer syntax

pointer_field -- This is an 8-bit field whose value shall be the number of bytes, immediately following the pointer_field until the first byte of the first section that is present in the payload of the Transport Stream packet (so a value of 0x00 in the pointer_field indicates that the section starts immediately after the pointer_field). When at least one section begins in a given Transport Stream packet, then the payload_unit_start_indicator (refer to 2.4.3.2 on page 21) shall be set to 1 and the first byte of the payload of that Transport Stream packet shall contain the pointer. When no section begins in a given Transport Stream packet, then the payload_unit_start_indicator shall be set to 0 and no pointer shall be sent in the payload of that packet.

2.4.4.3 Program association table

The Program Association Table provides the correspondence between a program_number and the PID value of the Transport Stream packets which carry the program definition. The program_number is the numeric label associated with a program.

The overall table is contained in one or more sections with the following syntax. It may be segmented to occupy multiple sections.

Table 2-25 -- Program association section Syntax	No. of bits	Mnemonic
program_association_section() {
}

2.4.4.4 Table_id assignments

The table_id field identifies the contents of a Transport Stream PSI section as shown in table 2-26 below.

Table 2-26 -- table_id assignment values value	description
0x00	program_association_section
0x02	TS_program_map_section
0xFF	forbidden

2.4.4.5 Semantic definition of fields in program association section

table_id -- This is an 8 bit field, which shall be set to 0x00 as shown in table 2-26 above.
section_syntax_indicator -- The section_syntax_indicator is a 1 bit field which shall be set to '1'.
section_length -- This is a twelve bit field, the first two bits of which shall be '00'. The remaining 10 bits specify the number of bytes of the section, starting immediately following the section_length field, and including the CRC. The value in this field shall not exceed 1 021(0x3FD).
transport_stream_id -- This is a 16 bit field which serves as a label to identify this Transport Stream from any other multiplex within a network. Its value is defined by the user.
version_number -- This 5 bit field is the version number of the whole Program Association Table. The version number shall be incremented by 1 modulo 32 whenever the definition of the Program Association Table changes. When the current_next_indicator is set to '1', then the version_number shall be that of the currently applicable Program Association Table. When the current_next_indicator is set to '0', then the version_number shall be that of the next applicable Program Association Table.
current_next_indicator -- A 1 bit indicator, which when set to '1' indicates that the Program Association Table sent is currently applicable. When the bit is set to '0', it indicates that the table sent is not yet applicable and shall be the next table to become valid.
section_number -- This 8 bit field gives the number of this section. The section_number of the first section in the Program Association Table shall be 0x00. It shall be incremented by 1 with each additional section in the Program Association Table.
last_section_number -- This 8 bit field specifies the number of the last section (that is, the section with the highest section_number) of the complete Program Association Table.
program_number -- Program_number is a 16 bit field. It specifies the program to which the program_map_PID is applicable. When set to 0x0000 then the following PID reference shall be the network PID. For all other cases the value of this field is user defined. This field shall not take any single value more than once within one version of the program association table.
Note - The program_number may be used as a designation for a broadcast channel, for example.
network_PID -- The network_PID is a 13 bit field, which is used only in conjunction with the value of the program_number set to 0x0000, specifies the PID of the Transport Stream packets which shall contain the Network Information Table. The value of the network_PID field is defined by the user, but shall only take values as specified in table 2-3 on page 22. The presence of the network_PID is optional.
program_map_PID -- The program_map_PID is a 13 bit field specifying the PID of the Transport Stream packets which shall contain the program_map_section applicable for the program as specified by the program_number. No program_number shall have more than one program_map_PID assignment. The value of the program_map_PID is defined by the user, but shall only take values as specified in table 2-3 on page 22.
CRC_32 -- This is a 32 bit field that contains the CRC value that gives a zero output of the registers in the decoder defined in Annex B after processing the entire program association section.

2.4.4.6 Conditional access table

The Conditional Access (CA) Table provides the association between one or more CA systems, their EMM streams and any special parameters associated with them. Refer to 2.6.16 on page 74 for a definition of the descriptor() field in table 2-27 on page 49below.

The table is contained in one or more sections with the following syntax. It may be segmented to occupy multiple sections.

Table 2-27 -- Conditional access section Syntax	No. of bits	Mnemonic
CA_section() {
}

2.4.4.7 Semantic definition of fields in conditional access section

table_id -- This is an 8 bit field, which shall be set to 0x01 as specified in table 2-26 on page 47 above.
section_syntax_indicator -- The section_syntax_indicator is a 1 bit field which shall be set to '1'.
section_length -- This is a 12 bit field, the first two bits of which shall be '00'. The remaining 10 bits specify the number of bytes of the section starting immediately following the section_length field, and including the CRC. The value in this field shall not exceed 1 021(0x3FD).
version_number -- This 5 bit field is the version number of the entire conditional access table. The version number shall be incremented by 1 modulo 32 when a change in the information carried within the CA table occurs. When the current_next_indicator is set to '1', then the version_number shall be that of the currently applicable Conditional Access Table. When the current_next_indicator is set to '0', then the version_number shall be that of the next applicable Conditional Access Table.
current_next_indicator -- A 1 bit indicator, which when set to '1' indicates that the Conditional Access Table sent is currently applicable. When the bit is set to '0', it indicates that the Conditional Access Table sent is not yet applicable and shall be the next Conditional Access Table to become valid.
section_number -- This 8 bit field gives the number of this section. The section_number of the first section in the Conditional Access Table shall be 0x00. It shall be incremented by 1 with each additional section in the Conditional Access Table.
last_section_number -- This 8 bit field specifies the number of the last section (that is, the section with the highest section_number) of the Conditional Access Table.
CRC_32 -- This is a 32 bit field that contains the CRC value that gives a zero output of the registers in the decoder defined in Annex B after processing the entire conditional access section.

2.4.4.8 Program Map Table

The Program Map Table provides the mappings between program numbers and the program elements that comprise them. A single instance of such a mapping is referred to as a "program definition." The program map table is the complete collection of all program definitions for a Transport Stream. This table shall be transmitted in packets, the PID values of which are selected by the encoder. More than one PID value may be used, if desired. The table is contained in one or more sections with the following syntax. It may be segmented to occupy multiple sections. In each section the section number field shall be set to zero. Sections are identified by the program_number field.

Definition for the descriptor() fields may be found in 2.6 on page 67 of this Specification.

Table 2-28 -- Transport Stream program map section Syntax	No. of bits	Mnemonic
TS_program_map_section() {
}

2.4.4.9 Semantic definition of fields in Transport Stream program map section

table_id -- This is an 8 bit field, which in the case of a TS_program_map_section shall be always set to 0x02 as shown in table 2-26 on page 47 above.
section_syntax_indicator -- The section_syntax_indicator is a 1 bit field which shall be set to '1'.
section_length -- This is a 12 bit field, the first two bits of which shall be '00'. The remaining 10 bits specify the number of bytes of the section starting immediately following the section_length field, and including the CRC. The value in this field shall not exceed 1 021 (0x3FD).
program_number -- program_number is a 16 bit field. It specifies the program to which the program_map_PID is applicable. One program definition shall be carried within only one TS_program_map_section. This implies that a program definition is never longer than 1016 (0x3F8). See Informative Annex C for ways to deal with the cases when that length is not sufficient. The program_number may be used as a designation for a broadcast channel, for example. By describing the different program elements belonging to a program, data from different sources (e.g. sequential events) can be concatenated together to form a continuous set of streams using a program_number. For examples of applications refer to Annex C.
version_number -- This 5 bit field is the version number of the TS_program_map_section. The version number shall be incremented by 1 modulo 32 when a change in the information carried within the section occurs. Version number refers to the definition of a single program, and therefore to a single section. When the current_next_indicator is set to '1', then the version_number shall be that of the currently applicable TS_program_map_section. When the current_next_indicator is set to '0', then the version_number shall be that of the next applicable TS_program_map_section.
current_next_indicator -- A 1 bit field, which when set to '1' indicates that the TS_program_map_section sent is currently applicable. When the bit is set to '0', it indicates that the TS_program_map_section sent is not yet applicable and shall be the next TS_program_map_section to become valid.
section_number -- The value of this 8 bit field shall be 0x00.
last_section_number -- The value of this 8 bit field shall be 0x00.
PCR_PID -- This is a 13 bit field indicating the PID of the Transport Stream packets which shall contain the PCR fields valid for the program specified by program_number. If no PCR is associated with a program definition for private streams then this field shall take the value of 0x1FFF. Refer to the semantic definition of PCR in 2.4.3.5 on page 24 and table 2-3 on page 22 for restrictions on the choice of PCR_PID value.
program_info_length -- This is a 12 bit field, the first two bits of which shall be '00'. The remaining 10 bits specify the number of bytes of the descriptors immediately following the program_info_length field.
stream_type -- This is an 8 bit field specifying the type of program element carried within the packets with the PID whose value is specified by the elementary_PID. The values of stream_type are specified in table 2-29 .

Table 2-29 -- Stream type assignments Value	Description
0x00	ITU T†\|†ISO/IEC Reserved
0x01	ISO/IEC 11172-2 Video
0x80-0xFF	User private

Note - An ITU T Rec. H.222.0†|†ISO/IEC 13818-1 auxiliary stream is available for data types defined by this Specification, other than audio, video, and DSM CC, such as Program Stream Directory and Program Stream Map.
elementary_PID -- This is a 13 bit field specifying the PID of the Transport Stream packets which carry the associated program element.
ES_info_length -- This is a 12 bit field, the first two bits of which shall be '00'. The remaining 10 bits specify the number of bytes of the descriptors of the associated program element immediately following the ES_info_length field.
CRC_32 -- This is a 32 bit field that contains the CRC value that gives a zero output of the registers in the decoder defined in Annex B after processing the entire Transport Stream program map section.

2.4.4.10 Syntax of the Private section

When private data is sent in Transport Stream packets with a PID value designated as a Program Map Table PID in the Program Association Table the private_section shall be used. The private_section allows data to be transmitted with a minimum of structure while enabling a decoder to parse the stream. The sections may be used in two ways: if the section_syntax_indicator is set to '1', then the whole structure common to all tables shall be used; if the indicator is set to '0', then only the fields 'table_id' through 'private_section_length' shall follow the common structure syntax and semantics and the rest of the private_section may take any form the user determines. Examples of extended use of this syntax are found in Informative Annex C.

A private table may be made of several private_sections, all with the same table_id.

Table 2-30 -- Private section Syntax	No. of bits	Mnemonic
private_section() {
section_syntax_indicator	1	bslbf
}

2.4.4.11 Semantic definition of fields in private section

table_id -- This 8-bit field, the value of which identifies the Private Table this section belongs to. Only values defined in table 2-26 on page 47 as "user private" may be used.
section_syntax_indicator -- This is a 1 bit indicator. When set to '1', it indicates that the private section follows the generic section syntax beyond the private_section_length field. When set to '0', it indicates that the private_data_bytes immediately follow the private_section_length field.
private_indicator -- This is a 1 bit user definable flag that shall not be specified by ITU T†|†ISO/IEC in the future.
private_section_length -- A 12-bit field. It specifies the number of remaining bytes in the private section immediately following the private_section_length field up to the end of the private_section. The value in this field shall not exceed 4 093 (0xFFD).
private_data_byte -- The private_data_byte field is user definable and shall not be specified by ITU T†|†ISO/IEC in the future.
table_id_extension -- This is a 16-bit field. Its use and value are defined by the user.
version_number -- This 5-bit field is the version number of the private_section. The version_number shall be incremented by 1 modulo 32 when a change in the information carried within the private_section occurs. When the current_next_indicator is set to '0', then the version_number shall be that of the next applicable private_section with the same table_id and section_number.
current_next_indicator -- A 1 bit field, which when set to '1' indicates that the private_section sent is currently applicable. When the current_next_indicator is set to '1', then the version_number shall be that of the currently applicable private_section. When the bit is set to '0', it indicates that the private_section sent is not yet applicable and shall be the next private_section with the same section_number and table_id to become valid.
section_number -- This 8-bit field gives the number of the private_section. The section_number of the first section in a private table shall be 0x00. The section_number shall be incremented by 1 with each additional section in this private table.
last_section_number -- This 8-bit field specifies the number of the last section (that is, the section with the highest section_number) of the private table of which this section is a part.
CRC_32 -- This is a 32 bit field that contains the CRC value that gives a zero output of the registers in the decoder defined in Annex B after processing the entire private section.

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