[mythtv] DVB-S with no SDT / NIT tables (REDUX)

Steven Ellis steven at openmedia.co.nz
Wed Dec 5 22:15:43 UTC 2007


On Thu, December 6, 2007 10:30 am, Dean Pemberton wrote:
> Hi everyone.
>
> Just over a month ago Steven Ellis made a post here regarding an issue
> very important to MythTV users in New Zealand and Australia.  You can
> view the post and thread here.
>
> http://www.gossamer-threads.com/lists/mythtv/dev/296989?page=last
>
>
> In summary the problem is that one DVB-S provider has chosen to
> broadcast their content in a way which does not use SDT/NIT tables.
> This is FTA content (unscrambled and not restricted) it is unknown why
> they do this.
>
> This content can be viewed on a number of STB and other Linux PVR
> solutions by inputting the v/a PIDs which are well known and widely
> available.  MythTV on the other hand, due to the way that it uses the
> PMT/PAT to get the PIDs has no way of allowing a user to enter these by
> hand.
>
> There have been a number of suggestions in the previous thread as to how
> a solution to this could be implemeted (from DVB PID caching to
> hardcoding PIDs for certain channels), but it seems to have lost a bit
> of traction.  I'd just like to reiterate that this feature will provide
> a large benefit to the majority of DVB-S MythTV users in Aus/NZ and we
> are more than willing to provide all the help we can to work out a
> solution.

One option I've been investigating is to use the atsc_major_chan and
atsc_minor_chan fields in the channel table to indicate the vPID and aPID
for the channel. The mplexid would still point at the correct multiplex,
and we'd use a special serviceid such as "-1" to indicate we shouldn't
perform a normal PMT based lookup and instead use the hard coded a/v PIDS

Hence for "hidden" PIDS we'd use the channel table as follows
mplex -> Points at Multiplex
serviceid = -1 -> Indicates hidden channel with forced PIDS
atsc_major_chan = vPID
atsc_minor_chan = aPID

Feedback or alternative direction appreciated. Then I can look at
implementing something that the local NZ/AU MythTV community can test.

Steve




--------------------------------------------
Steven Ellis - Technical Director
OpenMedia Limited - The Home of myPVR
email   - steven at openmedia.co.nz
sales   - sales at openmedia.co.nz
support - support at openmedia.co.nz
website - http://www.openmedia.co.nz


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