Bolt Pixelation on Switched Digital Video channels

Discussion in 'TiVo Bolt DVR/Streamer' started by WKeith, Jan 28, 2019.

  1. WKeith

    WKeith New Member

    Jan 26, 2019

    On Cox cable here, they recently (11/2018) moved their channels around with most channels above 1000 now using switched digital video (SDV) service. For 2 years up to this point, I have had no problems whatsoever with any channels. Since this switch, I now see bursts of pixelation on both live and recorded streams, but only on these SDV channels. Channels not using SDV are fine, both live and recorded. The recorded stream for the SDV channels show the exact same breakup/pixelation as was seen on the live stream, when played back on the Bolt at exactly the same spots. Breakups happen about every 10 to 15 seconds, but seem to be fairly random. This is very repeatable.

    Here's the clincher - Live TV and recordings are fine when played back on both Tivo minis! There is no pixelation or breakups whatsoever. I even hooked the TV that was on one of the Tivo-minis to the Bolt with a 3 foot high quality HDMI cable and it exhibits the breakups/pixelation just like the other TV, so it is definitely just a problem with the Bolt output. It's also fine on the Cox Contour box, which I don't really use, but I did hook it up long enough to see if it experiences the same problem. It doesn't.

    I have a Bolt with a Cisco tuning adapter and Cisco cable card as well as 2 Tivo minis on Moca.
    The diagnostics on all channels are about the same :

    Signal level = ~90%
    RS Uncorrected = 0
    RS Corrected = 0

    This is for any and all channels over many hours, whether on the switched digital video channel or not. I don't see how this could be a signal issue with errors at 0, signal very strong and both live and playback fine on both TV minis.

    It looks like there is some decoding problem inside the Bolt after coming off the HD for streams that were sourced by a SDV channel.

    I have changed ALL coax, HDMI and USB cables to new ones and I reboot everything nightly via an outlet timer. There is a Moca POE filter at the cable entry, followed by a 5 way splitter, feeding the Bolt, 2 Tivo minis, cable modem and tuning adapter. There is an 2nd Moca POE at the tuning adapter input and a 3rd Moca POE at the input of the cable modem. The tuning adapter output is unused as recommended by Tivo. (As I said, this setup worked fine for over 2 years.)

    Tivo support is sending me a refurbished box in case there is an issue with my particular hardware, but I have a sneaking suspicion that the new box will have the same issue. They won't escalate this issue until I see if the new box experiences the same problem.

    I was wondering if anyone else has seen this.


    UCLABB Well-Known Member

    May 29, 2012
    Riverside, CA
    My guess is that the box is bad. Since the minis work and the signal strength is fine, it sure appears that the Bolt is screwing up. Let us know if the new box works.
  3. WKeith

    WKeith New Member

    Jan 26, 2019
    2/1/19 Update:

    I received the new Tivo Bolt box, put the old cable card in, activate it through Cox and it has exactly the same problem - intermittent pixelation on the SDV channels, both live and recorded playback. And like before, when playing these recordings back on both Tivo minis, there is no pixelation whatsoever. It is a perfect playback.

    Again, the signal was 90% and SNR was 35dB, with 0 RS corrected and 0 RS uncorrected. There are no issues at all on the channels not using the SDV service (those I can watch without the TA).

    So, I got a new cable card and a new tuning adapter from Cox to put with the new Tivo box. Exactly the same thing is happening now with the new Bolt, new cable card and new TA.

    I strongly believe Tivo's software decoder (or is it a HW decoder) within the Bolt has some kind of bug or maybe the stream itself has some issue and the bolt is overly sensitive, yet the mini and the Countour box accept it just fine. The mini (I assume) pulls the raw stream off the HDD and decodes it within the mini and does not have the same issue.

    I'm hoping to escalate this with Tivo support on Monday (and hopefully get some of my money back for the replacement Bolt).

  4. L David Matheny

    L David Matheny Active Member

    Jan 29, 2011
    SE Ohio
    It’s an odd problem. “Live TV and recordings are fine when played back on both Tivo minis” implies that reception and recording to disk are perfect, since a Mini can’t fix bad data. And “no issues at all on the channels not using the SDV” seems to rule out HDMI problems. Swapping the Bolt seems to rule out sample defects, including a bad hard drive. So what’s left?

    Disconnect the tuning adapter to see if it could be demanding too much attention. If there are interrupt-handling issues or buffer management issues or disk drive speed issues, why wouldn’t those affect streaming to a Mini? The Bolt does juggle more tasks than a Mini. Do data rates for problem recordings tend to be higher?
  5. WKeith

    WKeith New Member

    Jan 26, 2019

    So... I was on the phone with Tivo support again with this issue yesterday. I explained to them that the replacement Bolt, along with a replacement cable card and tuning adapter changed nothing. I still see pixelation and line distortions every 10-15 seconds, but only on the switched digital video channels when live and recorded. Of course "live" really means recorded with a small delay, so the data path for both is essentially the same, I presume.

    Once again, they tried the "your SNR is too high" BS and I explained that I am not buying it and that I am at the point where I will drop Tivo completely and mount a bad PR campaign against them (well, on social media at least). I tried to explain that if the SNR number is indeed measuring SNR, then the claim that your SNR is too high is saying precisely that you don't have enough noise in your system, ridiculous and insulting to anyone with a technical background. I'm not even sure how one would ADD noise to a system with an SNR of 35dB to bring it down to 29dB (or whatever their magic maximum SNR number is). The only way I can think of is to put attenuation in the input path, then add an amplifier that will add noise.

    Before I actually went that route (only to prove them wrong), I decided to try to go "up the chain" and ask for this tech's supervisor. I waited on hold for about 15 minutes, but finally got someone who was a little more interested in listening to me. She walked me through several new diagnostic screens and concluded that indeed there doesn't seem to be any issue with the incoming signal (other than that the SNR is higher than they recommend - SIGHHHH...)

    I walked her back at that point and pointed out that on channels with the same SNR, but not digitally switched, there is no issue. I then reminded her that I also see no pixelation of any kind on the Tivo minis whether playing live TV or the recorded program that shows the pixelation and dropouts on the Bolt.

    At that point, a light bulb seemed to go off with her and she realized what I was really saying - the feed coming off the HDD was only scrogged when playing on the Bolt, not the mini! Thank goodness. Finally, someone is listening to me and not reading a checklist to have me go through. I verified with her on line that the recording I had made consistently and repeatedly had errors in exactly the same spots in exactly the same way when played back on the Bolt, yet when played back on the mini, no such video pixelation or breakup whatsoever is seen.

    She agreed to escalate this to a higher level, with a high priority and said someone may be calling me to get more information. I suggested they copy over the recording I have that shows the problem, but she doesn't know if this is even possible. I'm hoping someone at Tivo is willing to go that far and will take me up on this offer to help trouble shoot. There is no doubt they have some way of copying my recording into their system in some lab in order to look at the stream and trouble shoot this.

    I will keep you posted.

  6. powrcow

    powrcow Active Member

    Sep 27, 2010
    Any resolution to this?

    I have similar symptoms but to a lesser extent, but I also have a Premiere instead of a Bolt. Like you, the Mini does a great job but the Premiere has pixelation that occurs probably once every 5 minutes (or longer) for me.

    I'll add one additional wrinkle: many of my SDV channels are also MPEG4 while I don't think I have any non-SDV MPEG4 channels.
  7. WKeith

    WKeith New Member

    Jan 26, 2019
    Sorry that I never posted a resolution...

    Within a day of so of the last posting, the problem completely went away. Someone from Tivo support called the very day I noticed it was fixed and asked if I was still seeing the problem. I said that the problem had indeed disappeared. She said that Tivo had been in contact with Cox in my area and Cox did something to resolve it, but she wouldn't give me (or didn't know) any details. Cox never contacted me.

    So, it's still a mystery as to what the problem was and it has not returned. Our service has been very reliable since then. I asked about the issue with the Mini not seeing the pixelation on the recordings that are seen on the Bolt and she said they didn't do anything to deal with that specifically and that since the problem is resolved, they would do nothing else and the ticket would be closed.

    I'm guessing that there really was some issue with an amp or encoder on Cox's end, causing errors in the stream that the Bolt is very sensitive to, but the Mini and the Cox box are not. I wish I had more information for you.

    I suggest you stay on Tivo and try to get them to escalate this. Find someone that actually understands that the Premier is seeing the pixelation while the Mini is not on the same recording and why they should be concerned about that. I finally got someone to understand that at a higher level and that is when things started to happen. Of course they made me swap out the box, all my cables and splitters and repeated the "your SNR is too high" mantra many times before they took it seriously enough to get involved with Cox to find the problem.

    Good luck.
    Mikeguy likes this.

Share This Page