[mythtv-users] How does myth use info in channel table to tune QAM channels?

[Michelle Dupuis]

I'm working on a bash script to merge XMLTV data (downloaded from
mythfilldatabase) with channel data (from myth scans) - since I had a
somewhat similar problem of data not matching up.
 
If you want to give it a try just email me.
 
-MD-

  _____  

From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Michael Thome
Sent: Wednesday, May 30, 2007 4:59 PM
To: Discussion about mythtv
Subject: Re: [mythtv-users] How does myth use info in channel table to tune
QAM channels?


Brian Walter wrote: 

Michael Thome wrote:

  

Which database fields does myth use to tune QAM channels?  How do these 

rules interact with zap2it lineups?



Example: here is an extract of what the channel table looks like after a 

successful scan:



mysql> SELECT 

chanid,channum,freqid,callsign,xmltvid,tvformat,mplexid,serviceid,atsc_major
_chan,atsc_minor_chan 

FROM `channel` WHERE `sourceid` = '5';

| chanid | channum | freqid | callsign     | xmltvid | tvformat | 

mplexid | serviceid | atsc_major_chan | atsc_minor_chan |

|   5740 | 74#0    | 74     | UNKNOWN74#0  |         | Default  |     

120 |        65 |               0 |               0 |



for 5740, by watching the stream I can see it is WENH (xmlid 11418).  I 

assume I can add the xmltvid and scheduling will work, but I'd also like 

to fix the channum for the on-screen schedule (74#0 isn't mnemonic) - 

can I change channum to "11"?  callsign to "WENH"? What is mplexid? Why 

is tvformat entered as "Default" and not "ATSC"?  Shouldn't it be ATSC 

with atsc_major/minor_chan set to something useful?  As an aside, how'd 

we get from 74.65 (what an hdhomerun_config scan reports) to 74#0?



    



Looks like your in New England too :)



I have the same cable setup (comcast - Southern NH).  After scanning, I 

changed two fields (via mythweb) - the xmltvid and the frequency - in 

the sample you have above I believe BZ is 804 (from zap2it).  Use the 

'channel number' from zap2it for the freqid in the table.



After that, everything worked great.



Depending on the rest of your tuner options (I have a pvr500 for 

standard cable) the 74#0 type of channels are digital broadcast of 

analog (no hd stuff).  I found them to be 'noisy' and not very reliable 

and ended up deleting them.

Yep - north-shore MA.
I trimmed out WBZ from above as it is pretty much ok as scanned...  WENH,
though:
I looked at the code, and I cannot see anything in the *tuning* area that
should care at all about the various fields - what is critical is mplexid
which gives us real frequency and (qam256) modulation via the dtv_multiplex
table, and then the serviceid, which tells us which stream - it looks to me
like everything else is ignored for tuning purposes...

But, that just begs the question - I wonder if the grabber doesn't use the
same rules and messes with the channels when the channum is some other
(known) non-hd type.

Hmmm - maybe I'll see what happens when I bash HSN...

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