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Old 03-17-2014, 11:05 AM   #1
marklyn
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question on infrequent pixelation

When I first got my Roamio I went through a couple of weeks of diagnosing and/or replacing splitters and fixing sub-par coax connections, and other solutions to get my dB levels in an acceptable range. For the most part, my signal seems solid; however, on rare occasions when I'm watching recorded TV, there might still be some very slight pixelation and audio drops for a few seconds, but usually not bad enough to miss anything. The channels this occurs on may vary and at the time of the 'blips' there really isn't anything obvious happening on my internal network that should be causing this.

This was a behavior I'd come to accept with satellite, although the drops and pixelation lasted longer during a storm. When I moved to TWC cable, I expected this type of issue would be a thing of the past and even though I've spent considerable amount of time investigating and implementing the best solution I could find for my TWC connections, I'm still seeing this on an infrequent basis.

So, my question is, assuming one has what you'd consider a good signal, does this still just happen on rare occasions? Is it normal to see this happen, maybe 1-2 times a week (If I had to guess)?
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Old 03-17-2014, 12:07 PM   #2
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So, its in the recording and repeats in the same places if you re-watch a section?

What has TWC said?
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Old 03-17-2014, 12:15 PM   #3
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If you can catch this live or while recording go to DVR Diagnostics and note the Signal Strength, SNR and RS Error counts for the offending channel.

A "good" signal will have 80-99 signal strength, 33-36 dB SNR and zero (or very few, and not climbing rapidly) RS Error counts.
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Old 03-17-2014, 12:29 PM   #4
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So, its in the recording and repeats in the same places if you re-watch a section?

What has TWC said?
Yes, it's in the same location each time. The hard drive is a new one I bought at the time I got my Roamio in January of this year and it was rated very high for dependability and use with DVR's. I know drives can still be flaky even new ones but in my 25 years in IT, I've only seen one like that.
TWC was out during my initial setup and one subsequent follow up for a "missing channel". That's when new ends were put on coax and signal checked and re-checked. TWC serviceman proclaimed a very good signal before he left that day.
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Old 03-17-2014, 01:26 PM   #5
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Since it's repeatable, it's very unlikely to be the hard drive. I occasionally get a few frames with minor pixelation, that's just the nature of digital signals; there's bound to be occasional signal blips. My signal strengths on my Roamio are usually 90-95% across all channels.

I just recently had a recording where about 10-15 minutes was badly pixelated with garbled audio. Once my wife saw it, she remarked that the same thing happened recently on one of her shows. After thinking about any commonalities, I realized both shows were on the same night, same time slot. My money's on a temporary signal problem from TWC.

My guess is you're having intermittent signal issues, slightly more severe than mine since you also lose audio. My guess is that you'd have trouble getting and action out of TWC; they'd look quickly at your signal levels, see they were generally fine, and then blame the Tivo.
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Old 03-17-2014, 01:32 PM   #6
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Since it's repeatable, it's very unlikely to be the hard drive. I occasionally get a few frames with minor pixelation, that's just the nature of digital signals; there's bound to be occasional signal blips. My signal strengths on my Roamio are usually 90-95% across all channels.

I just recently had a recording where about 10-15 minutes was badly pixelated with garbled audio. Once my wife saw it, she remarked that the same thing happened recently on one of her shows. After thinking about any commonalities, I realized both shows were on the same night, same time slot. My money's on a temporary signal problem from TWC.

My guess is you're having intermittent signal issues, slightly more severe than mine since you also lose audio. My guess is that you'd have trouble getting and action out of TWC; they'd look quickly at your signal levels, see they were generally fine, and then blame the Tivo.
What you're saying makes sense. And you're right, I'd rather take a beating than call TWC out to look at something that they will likely not regard as a problem when they see signal strength.
I was just hoping to see if other people get this occasionally, also with known good signal strengths, to see if this is a normal 'glitch'.
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Old 03-17-2014, 01:38 PM   #7
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No, it's not normal as far as being a TiVo related problem. An exception to that is I've found on occasion when transferring a show to my Roamio Pro (MRV or TTCB) it really seems to hinder the performance of the Roamio to a point once where TiVo could not play back a show properly without dropping frames. i.e. The transfer was overloading the Roamio so much it was affecting even playback. Note that transfers to Roamio can easily be 90+ Mbps.
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Old 03-17-2014, 02:06 PM   #8
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.........
TWC was out during my initial setup and one subsequent follow up for a "missing channel". That's when new ends were put on coax and signal checked and re-checked. TWC serviceman proclaimed a very good signal before he left that day.
What a TWC tech calls good signal and what a Tivo calls good signal can be very different, especially when variations across the entire cable bandwidth are considered, which the tech's measurements frequently don't cover in much detail.

Recommend checking signal in DVR diagnostics as given in my post #3 here.
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Old 03-17-2014, 02:15 PM   #9
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What a TWC tech calls good signal and what a Tivo calls good signal can be very different, especially when variations across the entire cable bandwidth are considered, which the tech's measurements frequently don't cover in much detail.

Recommend checking signal in DVR diagnostics as given in my post #3 here.
Sorry I forgot to post my counts, they consistently seem to be around 93-99 signal strength and 36-39 dB SNR. I don't know about the RS error counts, I'll have to check those when I get home.

The TWC tech was only really looking at the signal strength, which was around -11 or -12 dB before he replaced cable ends, then it went down to -6 or -7 dB and he was happy with that.
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Old 03-17-2014, 02:38 PM   #10
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There is apparently one TiVo bug that causes pixelation in the following circumstance: if you are recording overlapping recordings on the same channel. (For example, I record The Simpsons and Family Guy back-to-back, with padding on the end of The Simpsons.)

There's supposedly a fix for this coming soon, in the apron update, from what I've heard.
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Old 03-17-2014, 02:48 PM   #11
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There is apparently one TiVo bug that causes pixelation in the following circumstance: if you are recording overlapping recordings on the same channel. (For example, I record The Simpsons and Family Guy back-to-back, with padding on the end of The Simpsons.)

There's supposedly a fix for this coming soon, in the apron update, from what I've heard.
In that situation does the pixelation occur during the overlap part only?
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Old 03-17-2014, 02:50 PM   #12
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In that situation does the pixelation occur during the overlap part only?
Yes. It's confined only to a brief period in the second recording at the point where the padding for the first program ends. i.e. An 8:00 show padded to 8:32, followed by a second show starting at 8:30, would show brief pixelation in the second show at 2 minutes in.
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Old 03-17-2014, 03:01 PM   #13
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Yes. It's confined only to a brief period in the second recording at the point where the padding for the first program ends. i.e. An 8:00 show padded to 8:32, followed by a second show starting at 8:30, would show brief pixelation in the second show at 2 minutes in.
OK, then this wouldn't be that because I remember this happening twice (two different shows) in the last 30 or so minutes of the show.
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Old 03-17-2014, 04:26 PM   #14
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After I got Comcast to update my cable card firmware a few weeks ago (Scientific Atlanta PKM800) I noticed a significant reduction in the number of pixelation occurrences on my Roamio. Before the firmware upgrade I saw some amount of pixelation probably every day, and afterwards, I've seen maybe one or two occurrences in four or five weeks. A really big difference.

It looks like you have a different version (newer?) cable card that I have so I don't know if this is an issue for you, but I thought I'd chime in and let you know that perhaps your cable signal is not the problem.
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Old 03-17-2014, 07:28 PM   #15
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Pixelation, of course, means that at some point the signal is or was digital.

If it's analog all the way from camera to screen, you might get all sorts of problems before it gets inside your house, but pixelation isn't going to be one of them.

Even over the air analog from a few years back could occasionally experience pixelation because the signal was digitized somewhere at the network, or in the feed up to or down from the satellite to the broadcaster or cable company head end, or somewhere in the signal processsing before it got to the broadcast antenna to go out as an analog OTA signal, or in the cable company processing before being sent back out as analog cable.

Having seen this occur long before ever getting my first TiVo, my first instinct is to assume it's already in the signal coming into the house from wherever, and not in my equipment.
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