[mythtv-users] [mythtv-commits] Ticket #3295: Scheduler schedules recordings on channels it doesn't receive

Bruce Markey bjm at lvcm.com
Wed Apr 18 22:43:54 UTC 2007


Michael T. Dean wrote:
> On 04/18/2007 01:25 PM, Adam Brewster wrote:
>>> On 04/11/2007 05:56 PM, MythTV wrote:
>>> 
>>>> #3295: Scheduler schedules recordings on channels it doesn't
>>>> receive
>>>> 
>>>> I've found a little problem with the way mythtv schedules
>>>> programs.
>>> .
>>> 
>>>> If more than one capturecard is connected to a single
>>>> inputsource, mythtv assumes that it can receive every channel

There is no such terminology in myth as "inputsource".

>>>> associated with the inputsource on either capturecard.
>>>> Normally this is probably true, but I've found at least one
>>>> case where it isn't.
>>>> 
>>>> I've got a cable box connected by firewire (dct-6200) and a DVB
>>>> card (pchdtv-5500) both connected to the same feed.  The cable
>>>> box can get any channel, but the DVB card can only get a subset
>>>> of the channels.  I can't set up two different input sources

Then by definition, they are not the same source.

>>>> because mythfilldatabase changes the datadirect lineups, and I
>>>> end up with no data for a bunch of channels. The result is that
>>>> mythtv schedules recordings on channels it doesn't know how to
>>>> tune, and these recordings fail, so I miss a bunch of shows.
>>>> 
>>> Adam, the right way to configure your system is to use two
>>> different video sources /and/ two different DataDirect lineups.

Correct.

>> If more than one capturecard is connected to a single inputsource,
>>  mythtv assumes that it can receive every channel associated with
>> the inputsource on either capturecard. Normally this is probably
>> true, but I've found at least one case where it isn't.
>> 
> 
> By definition, a MythTV video source is a unique identifier for a
> source of programming.  The video source must be "connected" to one
> or more card inputs (on one or more capture cards) to allow capturing
>  programming from that source.  A video source must also have one or
> more channels that are used to specify what programming is available
> through that source.
> 
> Since the channels on a video source specify the programming
> available through that source, /all/ channels associated with a video
> source must be accessible through all inputs that are "connected"
> (i.e. mythtv-setup's input connections) to that video source.
> 
> Or, a little more concisely (and not quite so precisely) said, the
> video source is used to specify a unique collection of channels
> available to an input.

Correct. I assume that it usually falls on deaf ears when I make
a big deal about the difference between TV stations (buildings)
and channels (frequencies). Yes, it's all so self evident that
I'm being a bore to state the obvious. However, as soon as there
is any discussion of sources, inputs or channels, the distinction
goes right out the window.

Say I have an antenna for OTA HDTV (I don't but...) and I receive
the local NBC affiliate KVBC. I also have coax cable that carries
the signal from KVBC over the frequency known in the US as channel
3. The fact that I get channel 3 tells me nothing about how to
extract the digital packets from the KVBC digital broadcast.
Receiving the HD broadcast tells me nothing about what the tuner
card needs to do to tune in the carrier signal for the analog wave
coming from KVBC.

These are two different channels that are only relevant to different
devices amongst the sets of tuning information for the different
devices. They both carry programming from the same broadcast station
(in a building with employees). However they are different channels
(frequencies) on different wires going to different devices that
require different tuning information.

MythTV needs to know all the tuning information for each channel
(frequency) that can be received by an input. This collection
of channels (frequencies) is call a "Video Source". Two different
video sources may carry programming from the same station (building)
each on their own channel (frequency). Two sources may carry all
the same stations (buildings) over their channels (frequencies)
but that doesn't matter. Each Video Source needs to define the
channels (frequencies) that an input may need to tune to.

> So, if different channels are available through 2 different inputs, 
> MythTV requires 2 separate video sources (to provide the bounds
> within which the inputs can record).
> 
> This is by design.

Absolutely.

> The reason why ticket #3295 is invalid is because it attempts to
> reuse one video source for multiple, er, video sources.  :)  Since
> the available channels are different for the two different inputs, we
> /need/ two different video sources.
> 
> I think the issue you really want to fix is MythTV's current 1:1
> mapping between video sources and DataDirect lineups.  Currently,
> Myth requires that each video source use a different DataDirect
> lineup.  But, to allow

This has never been true, you can create as many video sources from
the same DD lineup as you'd like:

mysql> select sourceid,name,xmltvgrabber,lineupid from videosource;
+----------+--------------+--------------+-----------+
| sourceid | name         | xmltvgrabber | lineupid  |
+----------+--------------+--------------+-----------+
|        1 | CoxCableDD   | datadirect   | NV27420:- |
|        2 | CoxDigitalDD | datadirect   | NV27420:X |
|        4 | VCR          | /bin/true    | NULL      |
|        5 | Foo          | datadirect   | NV27420:- |
|        6 | Bar          | datadirect   | NV27420:- |
+----------+--------------+--------------+-----------+

If you need to have a different set of channels (frequencies)
to grab for each video source (set of channels (frequencies) for
an input) then you need to create a different lineup at zap2it
but there is nothing stopping you from using the same lineup for
more than one video source.

--  bjm



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