RTP Control Protocol (RTCP) Extended Report (XR) Block for MPEG2 Transport Stream (TS) Program Specific Information (PSI) Decodability Statistics Metrics Reporting
Extracted elements (20)
The block reports only ETSI TR 101 290 first- and second-priority indicators (basic and continuous monitoring), excluding third-priority indicators which are application-dependent and do not apply to all MPEG2 implementations. This scoping keeps the block focused on universally applicable decodability metrics.
This block supplements RFC 6990 (PSI-Independent Decodability Statistics Metrics Block) by adding PSI-specific counters. The separation allows implementations to report PSI-dependent and PSI-independent metrics independently, reflecting different monitoring capabilities.
PAT2 errors and PMT2 errors are defined as replacements for and improvements on PAT errors and PMT errors respectively. Receivers are required to prefer the _2 variants when available, ensuring backward compatibility while allowing upgraded reporting.
Reserved bits in the block header and the trailing Reserved field MUST be set to zero by senders and ignored by receivers, per Section 4.2 of RFC 6709.
The block length field MUST be the constant 6; receivers MUST discard the block if it is set to any other value.
Upon reception, if PAT_error_2_count is available (i.e., not 0xFFFF), receivers MUST ignore PAT_error_count. Similarly, if PMT_error_2_count is available, receivers MUST ignore PMT_error_count.
When any error count measurement is unavailable, the value 0xFFFF MUST be reported in the corresponding 16-bit count field.
XR blocks MAY be used without prior SDP signaling, in accordance with Section 5 of RFC 3611.
CAT_error_count is a 16-bit unsigned count of CAT errors. A CAT error occurs when PID 0x0001 contains a table with table_id other than 0x01, or when scrambling is employed but no table with table_id 0x01 (CAT) is present. Value 0xFFFF indicates measurement unavailable.
CRC_error_count is a 16-bit unsigned count of CRC errors occurring in any of the following PSI/SI tables: CAT, PAT, PMT, NIT, EIT, BAT, SDT, or TOT, as defined in ETSI TR 101 290 Section 5.2.2. Value 0xFFFF indicates measurement unavailable.
PAT_error_2_count is a 16-bit unsigned count of PAT2 errors. A PAT2 error occurs when a packet with PID 0x0000 containing table_id 0x00 does not appear at least every 0.5 seconds, contains a table with table_id other than 0x00, or has a non-zero Scrambling_control_field. This field supersedes PAT_error_count per ETSI TR 101 290.
PAT_error_count is a 16-bit unsigned count of PAT errors in the reported sequence interval. A PAT error occurs when PID 0x0000 does not appear at least every 0.5 seconds, does not contain table_id 0x00, or has a non-zero Scrambling_control_field. Value 0xFFFF indicates measurement unavailable.
PID_error_count is a 16-bit unsigned count of PID errors, which occur when no data stream is present for a given PID. This may result from multiplexing, demultiplexing, or remultiplexing operations. Value 0xFFFF indicates measurement unavailable.
PMT_error_2_count is a 16-bit unsigned count of PMT2 errors per program_map_PID. A PMT2 error occurs when table_id 0x02 does not appear at least every 0.5 seconds on each program_map_PID listed in the PAT, or has a non-zero Scrambling_control_field on any such packet. Supersedes PMT_error_count.
PMT_error_count is a 16-bit unsigned count of PMT errors. A PMT error occurs when a packet with table_id 0x02 does not appear at least every 0.5 seconds on the PAT-referenced PID, or has a non-zero Scrambling_control_field. Value 0xFFFF indicates measurement unavailable.
The SDP signaling extension uses the ABNF token 'xr-tpd-block = "ts-psi-decodability"' appended to the xr-format production to signal use of this report block in an SDP session description.
IANA assigns block type value 32, labeled 'MPEG2 Transport Stream PSI Decodability Statistics Metrics Block', in the 'RTCP XR Block Type' subregistry of the 'RTP Control Protocol Extended Reports (RTCP XR) Block Type Registry'.
IANA registers a new SDP 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'.
This RTCP XR block introduces no new security considerations beyond those described in RFC 3611 and RFC 6990. Implementors should refer to those documents for applicable threats and mitigations.
The MPEG2 TS PSI Decodability Metrics Block (BT=32) is 8 32-bit words long: BT (8 bits), Reserved (8 bits), block length (16 bits, constant 6), SSRC of source (32 bits), begin_seq (16 bits), end_seq (16 bits), followed by seven 16-bit error count fields (PAT_error_count, PAT_error_2_count, PMT_error_count, PMT_error_2_count, PID_error_count, CRC_error_count, CAT_error_count) and a final 16-bit Reserved field.