[xrblock] AD evaluation: draft-ietf-xrblock-rtcp-xr-psi-decodability-03

[Alissa Cooper <[e-mail]>]

I have reviewed this draft in preparation for IETF LC and I have some
questions before proceeding with the LC announcement.

In Section 3, there seem to be some inconsistencies between the way that
some of the fields are defined in the block and the way the corresponding
metrics are described in ETSI TR 101 290 (assuming
http://www.etsi.org/deliver/etsi_tr/101200_101299/101290/01.02.01_60/tr_101
290v010201p.pdf is the correct reference for that document):

(1) PAT_error_count is defined in the draft as:

"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 ID (PID) 0x 0000.  A PAT error occurs
      when it does not occur at least every 0.5s or the table has an ID
      other than 0x 00, as defined in section 5.2.1 of [ETSI].  Every
      program within the MPEG TS stream is listed in the PAT; if it is
      missing, then no programs can be decoded."

Whereas in the ETSI document, a PAT_error is defined as:

"PID 0x0000 does not occur at least every 0,5 s
a PID 0x0000 does not contain a table_id 0x00 ( i.e.
a PAT)
Scrambling_control_field is not 00 for PID 0x0000”

Is the definition in the draft supposed to be equivalent to the first two
conditions in the ETSI definition? If so, that is not quite clear from the
draft. Why is the Scrambling_control_field condition not also part of the
definition in the draft?

I have the same questions about PAT_error_2_count.

(2) In the draft, PMT_error_count and PMT_error_2_count have the exact
same definition. But in the ETSI document, a PMT_error is different from a
PMT_error_2. Here are the definitions from the ETSI document:

PMT_error:
"Sections with table_id 0x02, ( i. e. a PMT), do not
occur at least every 0,5 s on the PID which is
referred to in the PAT
Scrambling_control_field is not 00 for all PIDs
containing sections with table_id 0x02 (i.e. a PMT)”

PMT_error_2:
"Sections with table_id 0x02, (i.e. a PMT), do not
occur at least every 0,5 s on each
program_map_PID which is referred to in the PAT
Scrambling_control_field is not 00 for all packets
containing information of sections with table_id
0x02 (i.e. a PMT) on each program_map_PID
which is referred to in the PAT"

Are the equivalent definitions of PMT_error_count and PMT_error_2_count in
the draft intentional? If so, why define the same metric twice, and why
make PMT_error_2_count different from the way PMT_error_2 is defined in
the ETSI document?

(3) The draft defines PID_error_count as:

"A count of the number of PID_errors that occurred in the above
      sequence number interval.  A PID_error occurs when MPEG TS streams
      are remultiplexed and any PID doesn't refer to an actual data
      stream, as defined in the section 5.2.2 of [ETSI]."


PID_error is defined in 5.2.1 of the ETSI draft, not 5.2.2. Is the
definition in 5.2.1 what this field in the block is supposed to correspond
to, or is it something else?

(4) CAT_error_count is defined in the draft as:

"A count of the number of CAT_errors that occurred in the above
      sequence number interval.  A CAT_error occurs when the table has
      an ID other than 0x 01,as defined in the section 5.2.2 of [ETSI].”

CAT_error is defined in the ETSI document as:

"Packets with transport_scrambling_control not 00
present, but no section with table_id = 0x01 (i.e. a
CAT) present
Section with table_id other than 0x01
(i.e. not a CAT) found on PID 0x0001"

Again I’m curious why the definition in the draft seems to have only one
portion of one of the conditions that appear in the ETSI document.

Thanks,
Alissa