[mythtv-users] what's the definition and usage of channel number, freqid, callsign and name of mythconverg.channel

Clark Lee clarkchen900 at yahoo.com.cn
Sun Sep 13 04:36:35 UTC 2009

Thanks very much, Mike!
It's very informative - should it be put in the wiki so that it can be easily searched out in future?


----- Original Message ----
From: Michael T. Dean <mtdean at thirdcontact.com>
To: Discussion about mythtv <mythtv-users at mythtv.org>
Sent: Sunday, September 13, 2009 3:05:29 AM
Subject: Re: [mythtv-users] what's the definition and usage of channel number, freqid, callsign and name of mythconverg.channel

On 09/12/2009 05:58 AM, Clark Lee wrote:
> I am trying to setup channel information for Beijing's local digital cable broadcast for mythtv.
> The digital cable company provide a free STB that can be controlled by a remote. I managed to use LIRC and external script to control it, switch the channel by sending digital channel number. One digital channel number is corresponding to one specific channel. E.g. "1" is for "China Central Television Station - 1".
> Because there is no XMLTV data available, I am editing the 'channel' table in mythconverg database manually.
> However, I am a bit confused about the following columns and what I should fill in for digital cable case.
> channum;
> => no idea  

Any unique value (unique across all defined channels on all defined sources) you want to use to tell LiveTV to change to that channel.  The only time any 2 channels should /ever/ have the same channel number is if they have identical content and you don't want them to both appear on the Electronic Program Guide (see callsign, below).

> freqid;
> => from my past experience it is used in Analog TV case where it is used to control the tuner.

Any unique value that conveys all information necessary for an external channel change script to determine how to change channel and to which channel to change.  This can be a channel number, as used by your STB, or some value that your change channel script uses to do a lookup of required information.

In the case where you're using a card's tuner, the freqid should be the frequency (in kHz) or the frequency identifier corresponding to the desired frequency in the specified frequency table.  (So, for example, "frequency/channel 2" in a US cable frequency table.)  Specific allowed identifiers are determined by the chosen frequency table.

> callsign;
> => no idea...

Any value that's unique across all channels on all inputs that have differing content.  The /only/ time any 2 channels should have the same callsign is if they have "substantially identical" content (where the definition of "substantially identical" is very subject, but should generally be taken to mean, "exactly identical").  The callsign is used by the scheduler to determine which channels can be used for "this channel" rules--i.e. "this channel" means all channels with the same callsign.

Note that if 2 channels have the same callsign /and/ the same channum, they will be represented as only a single row in the Electronic Program Guide rather than showing 2 identical rows next to each other.

> name;
> => This seems should be the real name (i.e. man readable names) of the channel.

Yes, human-readable name you want to use in displaying information about the channel.  It's value is irrelevant to Myth and is used only in display.

> Which one is used as the input parameter for "external channel changer"?

freqid, as above.

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