Error locking on to only one channel, every other channel works perfectly. (1 Viewer)

[mores369]

I have a strange error that I've been seeing since the release of MediaPortal 1.2.3 (although it may have been happening before but not nearly as often). I'm using Windows Home Server 2011, and haven't had a problem like this before installing 1.2.3 that I know of.
What happens is this: Every channel I try to record works perfectly fine except for one. In trying to figure out what was happening, I started watching live tv and I found that the problem is completely repeatable. If I try and watch channel 15-1, it eventually stalls and complains that there is no channel lock. If I then move to any other channel (in this case 27-1), the tv comes on within a few seconds like normal. If I then go back to channel 15-1, it works fine. This is the same story every time I restart MediaPortal. Has anyone seen this error before?

Attached are the diagnostics as requested. If you look at the tvserver_tv file, the error occurs at 2012-07-04 15:05:06.687806. You can see the channel not lock on 15-1, work perfectly on 27-1, and then work on 15-1.
Thanks!

 

[mm1352000]

Hi mores369

This might be a question for the SiliconDust folks.
For the channel to stop in mid flight suggests to me that the tuning parameters that you're using might not be ideal. Have you checked that the frequency settings for that channel are correct according to the SD database?
http://www.silicondust.com/support/channels/

mm

 

[RonD]

as an experiment do these stations work correctly with hdhomerun SW?

Disable MePo TV Server, use hdhomerun QuickTV to watch the good/suspect channels. Use hdhomerun "Config" tool to monitor channel stats using QuickTV.

Start MePo, start hdhomerun "Config" tool to monitor channel stats when you use MePo to view the good/suspect channels. Start TV Server Config, select channels to "preview" good/suspect channels and use hdhomerun "Config" tool to monitor channel stats.

 

[mores369]

Thanks for the quick responses. I triple checked the settings on my HDHomeRun, and everything works fine there. I can use the quick view and watch channels with no problem at all. It never glitches as far as I can tell.

In fact, right now, I have MP TV server config open, in manual control, trying to watch channel 15-1, along with HDHR config open. If I try and start channel 15-1, it says "no signal" and I can still watch the channel using HDHR. If I start channel 27-1, it works fine, and then if I switch to 15-1, then it works. Absolutely repeatable. This is the weirdest thing. Any other diagnostic ideas?

 

[RonD]

I use a couple of HDHR tuners with BeyondTV and MePo for ATSC without problems, so I know in general HDHR works fine for MePo. Looking at your log files looks like you are using basic cable and QAM.

In the HDHR config tool, the Program line shows the Virtual Channel (15-1, 27-1, etc) and Channel Name (WMTV-DT WKOW-DT). For ATSC the Channel Line shows "us-bcast" and the RF Channel. Not sure what shows up for QAM. When you see the bad and good behavior with 15-1 and 27-1, what RF channel do you see? If you use HDHR QuickTV the Config program will show the correct RF channel.

 

[RonD]

mm1352000,

I looked at the July 4 log files "tvserver_tv.log" I noticed something different between 1st CH 15-1 failing case and the 2nd CH 15-1 passing case. Not sure if this is normal behavior or an indication of a problem.

lock_prob.zip has an excel spreadsheet (no macros) with failing case (left COL-A) and passing case (right COL-C). This is lined up so both attempts to tune to 15-1 are aligned. The pass/fail cases match until row 74. The yellow highlight shows the lines I thought were interesting. The 1st lines that differ are the following.

FAILING
2012-07-04 15:05:06.887818 [(22)]: atsc:using previous channel tuning settings
PASSING
2012-07-04 15:07:07.323706 [(22)]: atsc:using new channel tuning settings

I have no idea what goes on in the code but why did the 1st attempt at tuning 15-1 use the "previous tuning settings"? If there are problems with the zip/spreadsheet, the "lock_prob.txt" file shows the FAIL/PASSING log file lines I thought were interesting.

 

[mm1352000]

According to MP TV Server, the details are:


Frequency = 565250 kHz
RF Channel = 81 (***note: not used for tuning - the frequency must be correct)
Modulation = 256 QAM

According to the Silicondust DB (http://www.silicondust.com/hdhomerun/lineup_web/US:53715#lineup_8348160)... which could be wrong because I had to guess the details for you:

Frequency = 567000 kHz
RF Channel = 81.1
Modulation = 256 QAM

So MP appears to be tuning with "roughly" the right frequency. Could be the difference between base and center frequency.

Compare this with 27-1:

Frequency = 571262 kHz
RF Channel = 83
Modulation = 256 QAM

Frequency = 573000 kHz
RF Channel = 82.1
Modulation = 256 QAM

So the difference in frequency 1738 kHz for 27-1 and 1750 kHz for 15-1. Pretty similar... so why the difference in behaviour? I don't know.

You can try editing the frequency in TV Server for 15-1 and see if it makes a difference:
1. Find it in the TV Channel list.
2. Select and click "edit".
3. Select the row in the middle part of the window and click edit.
4. Enter the adjusted frequency.
5. Click OK.
6. Try to tune again.

Please keep in mind that running the two bits of software at the same time can cause conflicts. Better to close Quick TV while testing in MP, and also restart TV Server after testing in Quick TV. That is for fair testing...

mm

 

[mm1352000]

Hi RonD

Nice spotting!
This is normal behavior for TV Server - it is an attempt to save time in the tuning process. If TV Server thinks the tuner was previously tuned to the same frequency/RF channel then it skips tuning and attempts to just start timeshifting. If you look back to "2012-07-04 15:02:56.011758" before the example in lock_prob.txt you'll see that tuner 2 was previously tuned to the same frequency (565250 kHz), so therefore TV Server doesn't think it needs to force the tuner to tune... so it doesn't.

This behavior is one reason why the previously reported test results with QuickTV side by side weren't necessarily "fair" for TV Server.

mm

 

[RonD]

mm

I think the "side by side" was using the HDHR config tool that shows activity status on the tuner. For ATSC this is the RF channel, ATSC chan.subchan, Channel Name, signal strength/status. I run this in parallel with MePo and other SW if I want to see data dropout and other over the air problems. I've never/rarely see problems running the config tool with MePo or during channel scanning etc. It gives me some idea if I'm having antenna/signal problems.

so based on mm's comment that "using previous channel tuning settings" if the channel is the same is a "feature" and not a "bug"

 

[mores369]

Thanks for all your help, guys. I'll check it out as soon as I get home - I wrote that post and then left for vacation to Key West, FL. I'm a bit confused as to why HDHR can pick up the right frequency every time but MP misses occasionally, but I totally admit I'm learning all this for the first time. The cable company doesn't change frequencies, right? If the frequency doesn't change, then shouldn't MP keep using the last good frequency for each channel, or does it keep the default from the last time I did a full channel scan?

I'll try it next week - thanks again.