[mythtv-commits] Ticket #13463: Incorrect classification of data channels as TV channels

MythTV noreply at mythtv.org
Wed Jun 19 22:08:52 UTC 2019


#13463: Incorrect classification of data channels as TV channels
-------------------------------------+-------------------------------------
     Reporter:  Klaas de Waal        |      Owner:  Klaas de Waal
         Type:  Bug Report -         |     Status:  assigned
  General                            |
     Priority:  minor                |  Milestone:  needs_triage
    Component:  MythTV - Mythtv-     |    Version:  Master Head
  setup                              |   Keywords:  DVB SDT service_type
     Severity:  medium               |  Echostar
Ticket locked:  0                    |
-------------------------------------+-------------------------------------
 Some DVB satellite channels are incorrectly classified as TV channels. For
 example, channel "GFD Service" on Astra-1 19.2E is added to the list of TV
 channels even when in mythtv-setup/Channel Editor/Channel Scan/Desired
 Services only "TV" is selected.

 Analysis shows that "GFD Service" has service_type 0x96. This is not a TV
 service but a "user defined" value as defined in "Table 89:Service type
 coding", page 83, DVB Bluebook A038, Feb 2019.

 In MythTV the service_type evaluation is done in dvbdescriptors.h,
 function IsDTV. In addition to the service_type values defined in Table 89
 there are also a number of user defined values classified as TV.\\
 These additional values are used in the Dish/Echostar/Nimiq satellite
 channels to identify TV channels, as described in ticket #2372.
 The service type 0x96 used by "GFD Service" is one of those additional
 values.

 As I understand it, the user defined service_type values should be
 preceded by a private_data_specifier that identifies the user, as defined
 in
 https://www.dvbservices.com/identifiers/private_data_spec_id

 In the aforementioned Astra-1 streams the private_data_specifier is
 present and has the value 0x2 which corresponds to BskyB.

 The correct solution, as I see it, is to use the Dish/Echostar/Nimiq
 service types only when they have been preceded by the correct private
 data specifier. For this I need to know if there are private data
 specifiers present and what the values are. If somebody knows this please
 tell me!

 Another possibility is to use the original network ID to identify
 Dish/Echostar/Nimiq services. This is implicitly suggested in comment 5 of
 ticket #2372 where the table dtv_privatetypes is mentioned. This table
 contains a network ID and a list of service types. However, I have not
 found code that does actually use this table. Also, given the rather
 static nature of these numbers (ticket #2372 was closed 11 years ago) a
 hard-coded implementation might be the best solution.

 Comments are welcome!

-- 
Ticket URL: <https://code.mythtv.org/trac/ticket/13463>
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