[mythtv-users] New frequency for NY NBC OTA channel 4

Wed Apr 4 16:08:06 UTC 2018

On Wed, Apr 4, 2018 at 5:51 AM, stinga <stinga+mythtv at wolf-rock.com> wrote:
> On 03/04/18 01:26, Tom Dexter wrote:
>>
>> I just found out the hard way that apparently NY NBC channel 4
>> apparently changed frequency on April 1.
>>
>> I'd love to be able to just find out what the new frequency is and to
>> possible change it in the database. I HATE scanning for channels
>> frankly. For one thing I have a bunch of disabled Philadelphia
>> channels that I need to keep, but which can't be picked up without
>> turning my antenna, and among other things I do NOT want it to delete
>> any of those.
>
> I don't do a scan, I just find out when things don't record and fix the DB,
> here are my rough rules, if you don't know what you are doing then don't use
> :-)
> (I am in the UK)
>
>
> #Useful urls
> https://en.kingofsat.net/freqs.php?&pos=28.2E&standard=All&ordre=freq&filtre=no&aff=list
> https://www.lyngsat.com/Astra-2E-2F-2G.html
>
> #List chan details
> select c.xmltvid, c.callsign, c.chanid, c.channum, c.sourceid 'c.sourceid',
> dm.sourceid 'dm.sourceid', c.mplexid 'c.mplexid', dm.mplexid 'dm.mplexid',
> c.serviceid, dm.transportid, dm.frequency, dm.inversion, dm.symbolrate,
> dm.fec, dm.polarity, dm.modulation, dm.networkid from channel c,
> dtv_multiplex dm where c.mplexid = dm.mplexid and name like '%???%';
>
> #if nothing returned then the multiplex is probably missing - this is
> probably better
> select c.xmltvid, c.callsign, c.chanid, c.channum, c.sourceid 'c.sourceid',
> dm.sourceid 'dm.sourceid', c.mplexid 'c.mplexid', dm.mplexid 'dm.mplexid',
> c.serviceid, dm.transportid, dm.frequency, dm.inversion, dm.symbolrate,
> dm.fec, dm.polarity, dm.modulation, dm.networkid from channel c left join
> dtv_multiplex dm on c.mplexid = dm.mplexid where name like '%???%';
>
> #May need to add a new row into dtv_multiplex - see useful urls
> select
> mplexid,sourceid,transportid,networkid,frequency,inversion,symbolrate,fec,polarity,modulation,sistandard
> from dtv_multiplex where frequency=???;
> select
> mplexid,sourceid,transportid,networkid,frequency,inversion,symbolrate,fec,polarity,modulation,sistandard
> from dtv_multiplex order by frequency;
>
> #To insert a new frequency - needs to be done twice, for 3 and 5 sourceid's
> - I have HD and SD source ids
> insert into dtv_multiplex
> (sourceid,transportid,networkid,frequency,symbolrate,polarity)values(5,???,2,???,???,'?');
>
>
> #Then usually you need to alter the channel tables
> select xmltvid, name, c.callsign, c.chanid, c.channum, c.sourceid,
> c.mplexid, c.serviceid from channel c where name like '%??%';
> update channel set mplexid=??? where chanid=???;
> update channel set serviceid=??? where chanid in (???,???);
>
> #duplicate a channel row
> CREATE table x SELECT * FROM channel where chanid=???'
> #Find an empty chanid
> select chanid from channel order by chanid limit 5;
> update x set chanid=???, chanid=???;
> INSERT INTO channel select * from x;
> drop table x;
>
> --
> 'ooroo
>
> Stinga...(:)-)

Yea, I'm thinking very seriously about a similar approach going
forward...especially based on Gary's links there which tell me that
this will be happening to me a LOT over the next few years. A good
part of my job requires more or less living in MySQL so that part
isn't an issue.

In the case of US OTA I think creating new entries on dtv_multiplex
wouldn't be too tough. I'd actually forgotten that I had this perl
script that will list the freqid (which in this case is the UHF or VHF
channel) and the associated frequency that the table would need:

#!/usr/bin/perl
# Run this against /usr/share/dvb/atsc/us-ATSC-center-frequencies-8VSB
# to get a list of frequencies and channel numbers

$cnt = 1;
while ($line = <>) {
    chomp($line);
    @temp = split(/\s+/, $line);
    if ($temp[0] eq 'A') {
        $cnt++;
        $f = substr($temp[1], 0, length($temp[1]) - 6) . '000000';
        print "$f\t$cnt\n";
    }
}

Which does this:

perl chanfreq.pl /usr/share/dvb/atsc/us-ATSC-center-frequencies-8VSB
57000000    2
63000000    3
69000000    4
79000000    5
85000000    6
177000000    7
183000000    8
189000000    9
195000000    10
201000000    11
207000000    12
213000000    13
473000000    14
479000000    15
485000000    16
491000000    17
497000000    18
503000000    19
509000000    20
515000000    21
521000000    22
527000000    23
533000000    24
539000000    25
545000000    26
551000000    27
557000000    28
563000000    29
569000000    30
575000000    31
581000000    32
587000000    33
593000000    34
599000000    35
605000000    36
611000000    37
617000000    38
623000000    39
629000000    40
635000000    41
641000000    42
647000000    43
653000000    44
659000000    45
665000000    46
671000000    47
677000000    48
683000000    49
689000000    50
695000000    51
701000000    52
707000000    53
713000000    54
719000000    55
725000000    56
731000000    57
737000000    58
743000000    59
749000000    60
755000000    61
761000000    62
767000000    63
773000000    64
779000000    65
785000000    66
791000000    67
797000000    68
803000000    69

The link that Gary posted to that CSV file shows the from and to
channel numbers.

Anything's better than dealing with those scans.

Tom