[mythtvnz] Wellington Channel Retuning 19 June 2012

[Stephen Worthington]

On Sat, 16 Jun 2012 19:07:28 +1200, you wrote:

>On Sat, Jun 16, 2012 at 6:47 PM, tortise <tortise at paradise.net.nz> wrote:
>> Wellington users may not be aware of
>> http://www.rsm.govt.nz/cms/policy-and-planning/projects/digital-terrestrial-television-frequency-restacking/timing-and-channel-information
>>
>> For kaukau
>>
>> 50 > 32
>> 48 > 32
>
>no 48 goes to 34 I think.
>
>> 59 > 36
>>
>
>Yes I see we are next! (after you I mean).
>
>Are you suggesting just changing the freqid? I am not sure that will
>work if the serviceids change too.
>
>> I suppose it can also be done through SQL, but for the time it would take to
>> do I am presuming one can do this thru
>>
>> /mythweb/settings/tv/channels
>>
>> sql seems more risky and would take longer.
>>
>
>No it would be three lines, if simply changing the freqid works (see above)

The Kaukau changes are identical to what the Wharite changes in May
were, so here is the script I used then:

#!/bin/bash
# Update the channel frequencies for FreeviewHD from Kaukau for the
# 19-Jun-2012 changes.
source /etc/mythtv/mysql.txt
mysql -u $DBUserName -p$DBPassword -h $DBHostName $DBName << EOF
drop function if exists calcfreq;
delimiter $$
create function calcfreq(freqid int) returns int
begin
    return (506000000+(8000000*(freqid - 25)));
end$$
delimiter ;

set @freqid1 =    50;
set @newfreqid1 = 32;
set @freqid2 =    48;
set @newfreqid2 = 34;
set @freqid3 =    59;
set @newfreqid3 = 36;

update channel set freqid = @newfreqid1 where freqid = @freqid1;
update channel set freqid = @newfreqid2 where freqid = @freqid2;
update channel set freqid = @newfreqid3 where freqid = @freqid3;
update dtv_multiplex set frequency = calcfreq(@newfreqid1) where
frequency = calcfreq(@freqid1);
update dtv_multiplex set frequency = calcfreq(@newfreqid2) where
frequency = calcfreq(@freqid2);
update dtv_multiplex set frequency = calcfreq(@newfreqid3) where
frequency = calcfreq(@freqid3);

drop function calcfreq;
EOF

exit 0


This will change the "freqid" values, and the "frequency" values.  I
think the "frequency" value in the dtv_multiplex table is all that
matters, but if the "freqid" values are also there in the channel
table it would be best to have them matching.  The tuning code for
DVB-T looks up the mplexid in the channel table, and uses that to
index the dtv_multiplex table for the tuning data.  It uses the
"frequency" value from dtv_multiplex to tune to the multiplex, then
uses the "serviceid" from the channel table to select the channel on
that multiplex.  The "freqid" value in the channel table is used to
tune analogue channels, but as far as I can tell it is ignored when
tuning digital channels.

If you are using one of the other Wellington transmitters affected by
this change (Haywards, Fitzherbert or Baxter's Knob) and want to use
this script, you will need to fill in the correct values from the URL
above in the script's "set" statement pairs.

All that is changing are the frequencies the multiplexes are broadcast
on - there are no changes to other things like "serviceid" values.