[mythtv-users] MythTV and TV

[R. G. Newbury]

yan seiner wrote:
> R. G. Newbury wrote:
>
>   
>> You cannot just change the Input Connection if the Source is a different 
>> type.
>> The order in which things are done in mythtv-setup is slightly 
>> misleading in that a user can infer that the *card* is the most 
>> important part of the process. Actually the *lineup* is the most important.
>> The channel lineup, at least for North American users, will 
>> differentiate among cable, cable digital and broadcast.  Labs.zap2it.com 
>> will allow you ONE lineup of each of those types. Each of those has 
>> different connotations:  'cable' runs from 2 to 71 or so, 
>> 'cable-digital' has "channel numbers" which run up to 999 I guess, but 
>> the frequencies involved are all actually the same range as 'cable' but 
>> with subchannels. Broadcast can be analog or digital. Broadcast digital 
>> is handled in a similar manner to cable-digital, but the numbering 
>> scheme is different.
>>
>> Cards handle either analog or digital streams (NTSC or ATSC),  BUT NOT 
>> BOTH AT THE SAME TIME.
>>
>> That differentiation also determines what tuning information ( a 'tuning 
>> set') that mythtv sends to the card. Changing the information in mythtv, 
>> without any change to the lineup can produce a useless tuning set. I 
>> don't know what your card is, but if you are using an HD level (ATSC) 
>> card for OTA, then no wonder it will not work properly if you tell the 
>> card (through myth) that it should tune as if the input were a cable 
>> channel. Although transmission frequencies are the same for analog 
>> broadcast and analog cable channels and the underlying frequency may be 
>> the same for an HD digital broadcast, the manner in which the card 
>> abstracts the digital stream is quite different for a digital broadcast. 
>> To get an analog stream (channel 9 not channel 9_1) needs an analog 
>> module setup. ( For the pcHD3000, you use cx88_dvb for ATSC, and cx8800 
>> for NTSC).
>>
>> Digital broadcast is not the same thing as Analog broadcast and requires 
>> not only a different kernel module for the card but also a different 
>> setup in myth even if the lineup is still the same.
>>
>> Note also, that if the lineup type remains the same, you will run into 
>> problems if that lineup includes both analog and digital channels, since 
>> myth does not actually know that a card cannot do both. You must set up 
>> lineup <-> card pairings where that card can actually tune all of the 
>> channels in that lineup. So a PVR500 should never be paired against a 
>> cable-digital lineup or a broadcast lineup which includes digital 
>> channels: it cannot tune those channels. Similarly, a pcHD3000 should 
>> not be paired with a lineup which includes analog channels unless the 
>> card is set up to use an analog tuning module...
>>
>> And as far as I can tell, you cannot switch modules, 'on-the-fly' while 
>> myth is running, since myth checks each input card on startup, and would 
>> fail when it did not find the 'other' type of input.
>>
>> Geoff
>>
>>
>>
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>>  
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>>     
> Thanks.  I finally got around to reading this in peace.  Lots of good 
> information.
>
> The card I have currently is in fact an analog card - bt878, and, as 
> from my previous posting, I had digital channels mixed in there.  So I 
> will set it up accordingly.
>
> I also have a pcHDTV 3000 coming next week; I will set it up to receive 
> digital channels.  It's good to know that I have to set it up for one or 
> the other; I am very new to this part of Mythtv....
>
> My hope is to be able to use both cards simultaenously, but for now I 
> will be happy to get one to work... :-)
>
>   
Yes you can use both cards 'simultaneously', meaning that both will be 
in the box and you can use one or the other. I have a PVR500 card and an 
HD3000 card. I switch between them, for LiveTV with the 'Y' key on the 
keyboard. Setting up the digital is tricky but not insurmountable. You 
have to have a good setup for the default channel in mythtv-setup or you 
will never get the digital card working.
For recording, myth just selects a card which can tune the requested 
channel. In the case of the PVR500, it has a choice of 2 for analog 
cable channels.

Geoff



-- 
       R. Geoffrey Newbury			
     Barrister and Solicitor
 Suite 106, 150 Lakeshore Road West
    Mississauga, Ontario, L5H 3R2

  905-271-9600  Fax 905-271-1638
       newbury at mandamus.org