[mythtv] Adding PLP support (DTV_STREAM_ID)

[David Matthews]

On 28/01/2018 17:49, Torbjorn Jansson wrote:
> On 2018-01-28 16:42, Peter Bennett wrote:
>>
>>
>> On 01/28/2018 08:12 AM, Torbjorn Jansson wrote:
>>> Hello.
>>>
>>> i have a few questions but first some background.
>>>
>>> several years ago i bought a usb based dvbt2 tuner with the intention 
>>> to replace my pcie card.
>>> i picked a TT CT2-4650 since it was supposed to have linux support 
>>> already.
>>> turned out that was not true since i got a newer version of it with 
>>> no linux support, so with a bit of hacking on the drivers i was able 
>>> to get it working due to the similarities with other cards.
>>>
>>> but i quickly realized i could not tune to any dvb-t2 mux, after a 
>>> lot of troubleshooting i gave up and forgot about it.
>>>
>>> then a year or so later my dvb tv box broke down and i bought a new 
>>> one (vu+ solo4k) and to my surprise it had the exact same issue.
>>> after even more troubleshooting i found out i need to set PLP ID to 1 
>>> for tuning to work on dvb-t2 muxes.
>>>
>>> so then i realized that must be the same problem with my ct2-4650 and 
>>> it was.
>>> yesterday i got tvheadend working on the usb tuner successfully and 
>>> thats the first time i got the usb tuner to do something useful.
>>>
>>> BUT channel scanning is not working, so mux must be setup manualy, 
>>> that includes PLP ID and other paramters.
>>> so i think the drivers don't do auto detect like my pcie card does.
>>> and the downside of missing autodetect of plp is that most software 
>>> dont know how to handle plp and this applies to mythtv too.
>>>
>>>
>>>
>>> so for mythtv to work with this card i need to convince the backend 
>>> to specify plp when tuning.
>>> so a new mux paramter need to be added to database and then used 
>>> during tuning.
>>> as i understand it this is done with a property called: DTV_STREAM_ID 
>>> and i need to try to understand better how 
>>> libs/libmythtv/recorders/dvbchannel.cpp works.
>>>
>>> can someone give me any pointers about this?
>>> to start with i'm happy with a proof of concept hack that sets 
>>> DTV_STREAM_ID to 1 on all dvb-t2 tuning attempts, then if it works i 
>>> can try and get a proper patch for it.
>>>
>>> i probably wont be able to get the mux editor or settings working 
>>> since i'm not familiar with how the setup gui works.
>>> but if i get a new optional mux setting for plp in place then i'm happy.
>>>

I wrote the original patch to add support for DVB-T2 
https://code.mythtv.org/trac/ticket/12342 .  In the UK we don't use PLP 
or it may have been that the tuner I had auto-detected but either way 
there was no need to add PLP support at the time.  If you follow that 
link it should indicate roughly where to add the DTV_STREAM_ID property. 
  It's a long time since I looked at this but let me know if I can help.

David