WMC7 taking liveTV tuner while free tuner available: SOLVED

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fiteclub

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WMC7 taking liveTV tuner while free tuner available: SOLVED

#1

Post by fiteclub » Sat Feb 23, 2013 9:57 pm

This is a continuation of a discussion I started in this thread:

http://www.thegreenbutton.tv/forums/vie ... f=5&t=4057

I have started a new one since the topic on the previous thread was not relevant to this issue.

Briefly; for some people with free QAM tuners, WMC will, without warning or permission, "steal" the tuner providing LiveTV in order to record a scheduled program. This occurs even when there are plenty of tuners available to handle the recording task. In my particular case, I have an HDHomerun configured with two free QAM tuners and a Ceton InfiniTV4 PCIe 4 tuner OCUR Cablecard tuner. I am in Columbia SC on Time Warner Cable; all stations are encrypted except the broadcast network stations (ABC, CBS, NBC, FOX, PBS, CW). This issue only occurs (for me) when the HDHR freeQAM tuners are in play; it does not happen while watching or recording encrypted stations using the Ceton tuners.

In the thread posted above, forum member "crawfish" (post #23) pointed out that Silicondust had suggested that the problem might be related to bad PSIP data provided by cable companies in effect "confusing" WMC. Their suggested fix was to set VCT (virtual channel table) mode to BLOCKING from the usual AUTO setting on the "Advanced Tab" of the HDHR setup utility program. Once you do this, you must clear and rescan your channel data in WMC (big PIA). Now when WMC scans the HDHR tuners for stations, it reports back finding none (due to VCT block) but all you have to do is manually add the stations. Well, this afternoon I did this and after testing on several stations, I believe this fixed the issue. I cannot get WMC to take the LiveTV tuner using exact same conditions I preformed prior to the fix which ALWAYS produced the problem.

This does not explain how this occurs using analog tuners as at least one member has said happens so maybe there are other configurations that will induce the problem, but for those with free QAM tuners that experience this problem, I think bad PSIP data is the root of the issue. This explains why some folks with pretty much the exact same configuration don't experience the problem; they are on a cable system with "good" PSIP data.

crawfish

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#2

Post by crawfish » Mon Feb 25, 2013 10:31 pm

Glad it worked for you, and thanks for confirming one way or the other, as the fix isn't exactly quick and easy to try.

FWIW, the PSIP data could be valid per the relevant specifications, possibly an edge case WMC is handling wrong, creating problems that don't occur with other DVRs, that tend to persist forever due to Microsoft's neglect. The latest from SiliconDust goes beyond saying "WMC can get confused by the virtual channel table data sent by some cable providers" (they never described it as "bad data" in what I quoted) and attributes it to a bug in WMC, as can be seen here (at least until it ages off their forum), where they say, "There is a bug in WMC's code that handles the virtual channel information, causing it to occasionally mix up different channels on the same QAM channel":

http://www.silicondust.com/forum2/viewt ... 985#p81985

Whatever the case, the VCT Block mode seems to be the fix.

richard1980

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#3

Post by richard1980 » Mon Feb 25, 2013 10:58 pm

In the other thread, it was pointed out that the behavior exists with analog tuners/channels. Any thoughts?

fiteclub

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#4

Post by fiteclub » Mon Feb 25, 2013 11:42 pm

richard1980 wrote:In the other thread, it was pointed out that the behavior exists with analog tuners/channels. Any thoughts?
Not really; as I said in my original post above, this does not explain the problem for analog tuners as described in the referring thread. I have no analog tuner so really can't test or comment. It is obviously due to something different than bad or mishandled PSIP data.

fiteclub

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#5

Post by fiteclub » Mon Feb 25, 2013 11:53 pm

crawfish wrote:Glad it worked for you, and thanks for confirming one way or the other, as the fix isn't exactly quick and easy to try.

FWIW, the PSIP data could be valid per the relevant specifications, possibly an edge case WMC is handling wrong, creating problems that don't occur with other DVRs, that tend to persist forever due to Microsoft's neglect. The latest from SiliconDust goes beyond saying "WMC can get confused by the virtual channel table data sent by some cable providers" (they never described it as "bad data" in what I quoted) and attributes it to a bug in WMC, as can be seen here (at least until it ages off their forum), where they say, "There is a bug in WMC's code that handles the virtual channel information, causing it to occasionally mix up different channels on the same QAM channel":

http://www.silicondust.com/forum2/viewt ... 985#p81985

Whatever the case, the VCT Block mode seems to be the fix.
Sorry about misrepresenting your post; I had read somewhere that the problem might be with bad PSIP data so sorry I attributed this to your post.

Your link above to the SD forum thread states that the problem WMC has is with channels on the same QAM frequencies. This does not exactly match the symptoms my setup displayed as it happened for channels that had different QAM frequencies as well. Regardless, my system seems to be working correctly now after blocking the VCT.

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#6

Post by crawfish » Tue Feb 26, 2013 2:36 am

fiteclub wrote:Your link above to the SD forum thread states that the problem WMC has is with channels on the same QAM frequencies. This does not exactly match the symptoms my setup displayed as it happened for channels that had different QAM frequencies as well.
It's possible the issue is wider in scope than described by SiliconDust in the sentence or two they used to motivate their suggestion, which is why I thought it was still worthwhile to try the fix after you mentioned that, given the other parts (Clear QAM, VCT =/= block) matched.
Regardless, my system seems to be working correctly now after blocking the VCT.
That makes two confirmations for HDHR users I've seen, and no negatives. I guess one could argue that maybe it was manually adding the channels during your redo of TV setup that helped, but I don't believe it, as I always had to add my Clear QAM channels by hand, and I don't recall ever changing VCT. So blocking VCT would seem to be a necessary part of the fix.

fiteclub

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#7

Post by fiteclub » Tue Feb 26, 2013 2:45 am

crawfish wrote: I guess one could argue that maybe it was manually adding the channels during your redo of TV setup that helped, but I don't believe it, as I always had to add my Clear QAM channels by hand, and I don't recall ever changing VCT. So blocking VCT would seem to be a necessary part of the fix.
I agree; I have redone the WMC guide setup several times over the years and it never affected the tuner stealing problem that I had.

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