[mythtv] Guide service API "Group By" usage

Peter Bennett pb.mythtv at gmail.com
Mon Sep 28 15:43:47 UTC 2020

On 9/28/20 9:25 AM, Michael T. Dean wrote:
> On 09/27/2020 12:58 PM, Peter Bennett wrote:
>> On 9/25/20 2:56 PM, Peter Bennett wrote:
>>> The Guide API uses "Group by Callsign" with the result that if you 
>>> have two channels with the same callsign, one gets dropped off the 
>>> list. Is there any reason for this? I plan to fix it with the other 
>>> bugs I am fixing, if nobody knows of a reason for grouping that way.
>>> Comcast have a setup where many channels appears at least twice in 
>>> HD and once in SD. The two HD versions have the same callsign. The 
>>> second HD version is in the 1000+ range and grouped in ranges in 
>>> some way they think is helpful for channel surfing.
>>> Peter
>> On reconsidering this, I realized that if you have more than 1 "Input 
>> Connection" you could have the same channels repeated, for example on 
>> cable and over-the-air, and in that case will not want your channels 
>> duplicated. So I think I should rather leave this as is.
> Also, in MythTV, the call sign has been used to indicate a channel's 
> uniqueness.  Two channels with the same call sign are treated as the 
> same for the purposes of scheduling (therefore, no 2 channels should 
> be given the same call sign unless the content they broadcast is 
> substantially identical).
> The channel number is used to indicate that channels are to be treated 
> the same for Live TV .  If you tune a channel in Live TV by typing 
> channel number 13, you don't care which channel number 13 it 
> tunes--regardless of source or input.  If you have a preference which 
> is tuned in Live TV, the channels should be given different channel 
> numbers to allow differentiation when tuning Live TV by channel number.
> Both call sign and channel number are user-editable so that users can 
> change either or both of them.  So a user can have channels using WGBH 
> and WGBH-HD for call signs to differentiate a standard definition and 
> high definition version (or whatever indicator the user chooses) for 
> the purposes of recording scheduling with the "this channel" filter.  
> Or a user could have a  channel 13 for the channel the user prefers to 
> tune in Live TV and channel 1013 for one that's less desirable--for 
> example if 13 is usable from multiple inputs but 1013 is only usable 
> from a single input using, for example, a cable STB.
> In theory, the guide should only condense multiple channels to a 
> single listing if both the call sign and channel number are identical 
> for the channels.  If you're saying that's not the case in the 
> services API or something (it condenses if the call sign is identical 
> regardless of the channel number), that may be a bug.
> Mike
Yes that is what the services API does for the GetProgramGuide (Group by 
call sign and not channel number). My particular case was where two 
channels have the same call sign but different numbers and only one showed.

Here in the USA with cable we prefer channel number, the callsigns 
filled in by the guide service are not consistent. Many times they are 
some sort of abbreviation of the channel name, sometimes with -DT, -DT2, 
-DT3 etc. appended.

I recently came across somebody (I don't know where located) who has 
null channel numbers. I did not think that was allowed but it may mess 
up grouping by channel number. I am not sure if SQL will correctly group 
items that have null in their group by column.

Should null channel numbers be allowed?


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