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dtvscan interpretation?
PostPosted: Mon Jan 08, 2007 2:14 pm Reply with quote
mik
 
Joined: 31 Dec 2006
Posts: 16




I'm trying to figure out exactly what is going on when I run "dtvscan -q -o channels.conf". For instance, I see the following output for QAM-256 channel 80:
Code:
channel = 80 QAM_256
Signal: 100
look for sync
PAT found
PAT found
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
PAT found ckets
Unable to recieve valid packets
did find pat
`ERROR vct item ptr null couldn't get channel info

and on stdout (channels.conf) I see:
Code:

      :      :80.1 :80: 2:1

My understanding is that QAM streams may have many subchannels, and I'm wondering if (on my system), there are 15 active subchannels. I'm also told that my cable system doesn't include the channel identification information, so I'll have to do it myself... that's ok.

But stdout doesn't seem to include the subchannel information (though mythtv-setup seems to identify them).

So, questions:
1. Is watching livetv and doing channel edits the only way to do map channels to zaptoit? Does import-from-channels.conf work? How does it correlate the information with zaptoit? maybe by ChannelName (first field)?

2. Is there a way to at least get a channels.conf with all the subchannels listed so that I can use a text editor instead of the channel editor? (atsc)scan looks like it gives me a starting point - if I correlate with the channel table (us-cable-qam256) and discard the ones without video, I'm getting closer...

3. what does "PAT found" mean? versus "PAT found ckets" versus "Unable to recieve valid packets" (sic).
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PostPosted: Mon Jan 08, 2007 6:41 pm Reply with quote
xyzzy
 
Joined: 12 Feb 2006
Posts: 225




You might have more luck downloading my atscscan program (search forum for info). It's a somewhat more robust and informative channel scanner. It could also be that you are having signal quality/interference problems. Just because you see Signal: 100 doesn't mean everything must be ok! Channel scanning failure can be caused by the more general problem, "failure to work correctly." Sounds obvious I know, but just keep in mind that cause of your problem with channel scanning might not have anything to channel scanning. You also might not have anything on channel 80 to find!
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PostPosted: Tue Jan 09, 2007 7:16 am Reply with quote
mik
 
Joined: 31 Dec 2006
Posts: 16




xyzzy wrote:
You might have more luck downloading my atscscan program (search forum for info). ...

I actually tried it, but like at least one other, I'm running on a 64-bit setup that doesn't seem to grok your 32bit bin. Any chance you'd like to make the source available? At any rate, I'm not actually have any troubles - I'm just trying to understand the technology and tools so that I can hack the stuff myself.
Quote:
It could also be that you are having signal quality/interference problems. Just because you see Signal: 100 doesn't mean everything must be ok! Channel scanning failure can be caused by the more general problem, "failure to work correctly." Sounds obvious I know, but just keep in mind that cause of your problem with channel scanning might not have anything to channel scanning. You also might not have anything on channel 80 to find!
I picked a somewhat extreme case, but pretty much all the channels show the same behavior - apparently seeing some packets on some subchannels. dtvscan never emits any useful subchannel information for me (always 1). dvbtools' scan is much more informative, though it still doesn't attempt to decode anything by itself (I gather I need to use zap for that purpose), so there isn't any info on if the video is encrypted.

What I'd *really* like is a turnkey scanner that outputs a channels.conf of unencrypted content suitable for adding in names - even the mythtv scanner picks up annoyingly empty and encrypted channels. Heck, if myth would at least tell you that it the channel is encrypted instead of having to timeout.

thanks!
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dtvscan interpretation?
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