RTP Control Protocol (RTCP) Extended Report (XR) Block for MPEG2 Transport Stream (TS) Program Specific Information (PSI) Decodability Statistics Metrics Reporting

The European Telecommunications Standards Institute (ETSI) has defined a set of syntax and information consistency tests and corresponding indicators that are recommended for the monitoring of MPEG2 Transport Streams . The tests and corresponding indicators are grouped according to priority: Necessary for decodability (basic monitoring) Recommended for continuous or periodic monitoring Recommended for application-dependent monitoring This memo defines a new block type for use with MPEG2 Transport Streams to augment those defined in . The new block type supports reporting of the number of occurrences of each Program Specific Information (PSI) indicator in the first and second priorities listed in Sections 5.2.1 and 5.2.2, respectively, of . The third priority indicators are not supported. The metrics defined here supplement information from the PSI-Independent Decodability Statistics Metrics Block .

The use of RTCP for reporting is defined in . defines an extensible structure for reporting using an RTCP Extended Report (XR). This document defines a new Extended Report block for use with and .

The Performance Metrics Framework provides guidance on the definition and specification of performance metrics. The RTP Monitoring Architectures provides guidelines for RTCP XR block formats. The new report block described in this memo is in compliance with the monitoring architecture specified in and the Performance Metrics Framework .

These metrics are applicable to any type of RTP application that uses the MPEG2 TS standard format for multimedia data, for example, MPEG4 over MPEG2 TS over RTP. This new block type can be useful for measuring content stream or TS quality by checking TS header information and identifying the existence (and characterizing the severity) of bitstream packetization problems that may affect users' perception of a service delivered over RTP. It may also be useful for verifying the continued correct operation of an existing system management tool.

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119.

ETSI TR 101 290 generally defines indicators related to error events whereas the XR block defined in this document contains counts of occurrences of the indicators. The block defined in this document reports MPEG2 TS PSI decodability statistics metrics beyond the information carried in the standard RTCP packet format and PSI-Independent Decodability Statistics Metrics Block , which are measured at the receiving end of the RTP stream. It contains counts of seven metrics defined in ETSI TR 101 290 . Information is reported about basic monitoring parameters necessary to ensure that the TS can be decoded, including: Program Association Table (PAT) errors PAT2 errors Program Map Table (PMT) errors PMT2 errors Packet Identifier (PID) errors Information is also reported about continuous monitoring parameters necessary to ensure continuous decoding, including: Cyclic Redundancy Check (CRC) errors Conditional Access Table (CAT) errors In these parameters, PAT2 errors and PMT2 errors are actually replacements for and improvements on PAT errors and PMT errors, respectively, and are therefore preferred in future implementations. In addition, measurement results for some of these parameters (e.g., PAT errors or PMT errors) may be different based on whether scrambling is employed. The other parameters defined in Section 5 of are ignored since they do not apply to all MPEG2 implementations. For further detailed information on these parameters, see . The MPEG2 TS PSI Decodability Metrics Block has the following format:

0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | BT=32 | Reserved | block length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | SSRC of source | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | begin_seq | end_seq | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PAT_error_count | PAT_error_2_count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PMT_error_count | PMT_error_2_count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | PID_error_count | CRC_error_count | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CAT_error_count | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The MPEG2 TS PSI Decodability Metrics Block is identified by the constant 32;. These bits are reserved. They MUST be set to zero by senders ignored by receivers (see Section 4.2 of ). The constant 6, in accordance with the definition of this field in Section 3 of . The block MUST be discarded if the block length is set to a different value. As defined in Section 4.1 of . As defined in Section 4.1 of . As defined in Section 4.1 of . A count of the number of PAT errors that occurred in the above sequence number interval. The Program Association Table (PAT) is the only packet with Packet Identifier (PID) 0x0000. A PAT error occurs when (1) a packet with PID 0x0000 does not occur at least every 0.5 seconds, (2) a packet with PID 0x0000 does not contain table_id 0x00 (i.e., a PAT), or (3) the Scrambling_control_field in the TS packet header is not 00 for a packet with PID 0x0000. See Section 5.2.1 of . Every program within the MPEG TS stream is listed in the PAT; if it is missing, then no programs can be decoded. The measured value is an unsigned value. If the measurement is unavailable, then the value 0xFFFF MUST be reported. NOTE 1 of the table in Section 5.2.1 of recommends using PAT_error_2_count. Upon reception, if PAT_error_2_count is available (that is, other than 0xFFFF), then receivers MUST ignore PAT_error_count. A count of the number of PAT2 errors that occurred in the above sequence number interval. A PAT2 error occurs when (1) a packet with PID 0x0000 containing table_id 0x00 does not occur at least every 0.5 seconds, (2) a packet with PID 0x0000 contains a table with a table_id other than 0x00, or (3) the Scrambling_control_field in the TS packet header is not 00 for a packet with PID 0x0000. See Section 5.2.1 of . The measured value is an unsigned value. If the measurement is unavailable, then the value 0xFFFF MUST be reported. A count of the number of PMT errors that occurred in the above sequence number interval. A PMT_error occurs when (1) a packet containing a table with table_id 0x02 (i.e., a PMT) does not occur at least every 0.5 seconds on the PID that is referred to in the PAT or (2) the Scrambling_control_field in the TS packet header is not 00 for all packets with PID containing a table with table_id 0x02 (i.e., a PMT). See Section 5.2.1 of . The measured value is an unsigned value. If the measurement is unavailable, the value 0xFFFF MUST be reported. NOTE 2 of the table in Section 5.2.1 of recommends using PMT_error_2_count. Upon reception, if PMT_error_2_count is available (that is, other than 0xFFFF), then receivers MUST ignore PMT_error_count. A count of the number of PMT2 errors that occurred in the above sequence number interval. A PMT2_error occurs when (1) a packet containing table_id 0x02 (i.e., a PMT) does not occur at least every 0.5 seconds on each program_map_PID that is referred to in the PAT or (2) the Scrambling_control_field in the TS packet header is not 00 for all packets containing a table with table_id 0x02 (i.e., a PMT) on each program_map_PID that is referred to in the PAT. See Section 5.2.1 of . The measured value is an unsigned value. If the measurement is unavailable, then the value 0xFFFF MUST be reported. A count of the number of PID errors that occurred in the above sequence number interval. A PID error occurs when no data stream is present corresponding to a given PID. This may be caused by multiplexing or demultiplexing, then remultiplexing. See Section 5.2.1 of . The measured value is an unsigned value. If the measurement is unavailable, then the value 0xFFFF MUST be reported. A count of the number of CRC errors that occurred in the above sequence number interval. A CRC_error occurs if data corruption occurred in any of the following tables -- CAT, PAT, PMT, Network Information Table (NIT), Event Information Table (EIT), Bouquet Association Table (BAT), Service Description Table (SDT), or Time Offset Table (TOT), as defined in Section 5.2.2 of . The measured value is an unsigned value. If the measurement is unavailable, then the value 0xFFFF MUST be reported. A count of the number of CAT errors that occurred in the above sequence number interval. A CAT_error occurs when (1) a packet with PID 0x0001 contains a table with a table_id other than 0x01 (i.e., not a CAT) or (2) a packet does not contain a table with table_id = 0x01 (i.e., a CAT) when scrambling is employed (i.e., the Scrambling_control_field is set as a value other than 00). See Section 5.2.2 of . The measured value is an unsigned value. If the measurement is unavailable, then the value 0xFFFF MUST be reported. These bits are reserved. They MUST be set to zero by senders ignored by receivers (see Section 4.2 of ).

defines the use of the Session Description Protocol (SDP) for signaling the use of RTCP XR blocks. However, XR blocks MAY be used without prior signaling (see Section 5 of ).

This session augments the SDP attribute "rtcp-xr" defined in Section 5.1 of by providing an additional value of "xr-format" to signal the use of the report block defined in this document. The ABNF syntax is as follows:

xr-format =/ xr-tpd-block xr-tpd-block = "ts-psi-decodability"

When SDP is used in Offer/Answer context, the SDP Offer/Answer usage defined in for unilateral "rtcp-xr" attribute parameters applies. For detailed usage of Offer/Answer for unilateral parameters, refer to Section 5.2 of .

For usage outside of Offer/Answer, refer to Section 5.3 of .

New report block types for RTCP XR are subject to IANA registration. For general guidelines on IANA allocations for RTCP XR, refer to Section 6.2 of .

This document assigns the block type value 32 "MPEG2 Transport Stream PSI Decodability Statistics Metrics Block" in the "RTCP XR Block Type" subregistry of the IANA "RTP Control Protocol Extended Reports (RTCP XR) Block Type Registry".

This document also registers a new parameter "ts-psi-decodability" in the "RTCP XR SDP Parameters" subregistry of the "RTP Control Protocol Extended Reports (RTCP XR) Session Description Protocol (SDP) Parameters Registry".

The contact information for the registrations is:

RAI Area Directors <rai-ads@tools.ietf.org>

This proposed RTCP XR block introduces no new security considerations beyond those described in and .