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Picture pixellation while watching in pause mode

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    Geoff Thompson

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    Like others have previously commented I have seen occasional picture break up and pixellation issues. I too initially thought it was maybe an RF signal quality issue, but given I have multiple DTV devices in the house fed from the same distribution system was mystified as to why. Checking the signal strength for each mux on this box they are between 66 and 82, all with 100% quality. The COFDM signal is generally pretty robust so unless there was interference either external or internal to the box it ought not to be the culprit.
    What I have started to notice though and verified when it happened last night is that I was watching the recording effectively in "live pause mode". That is the programme was being recorded whilst at the same time I was watching it. I had pressed pause for a few minutes and then continued watching. Several times during the programme there were brief bursts of pixellation. When I watched the recording back again today at the points where the errors were, the recording appeared fine. That seems to rule out signal issues as being the cause in my case.

    It makes me wonder therefore if there could be hard disk/filesystem issues which mean that occasionally the playback buffers cannot access data quick enough. Last night I was recording 2 HD streams and playing back 1 HD stream. I would hope that if I'm recording a channel, watch it and then press pause that it uses the stream its already recording rather than starting a new "Pause Buffer". Otherwise that could be 3 HD streams to record.

    Just wonder if this could be the same scenario where others have observed picture break up. Don't know whether it is then related to number of record streams, time delay etc.

    | Fri 15 Jan 2021 20:43:51 #1 |
  2. grahamlthompson

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    Geoff Thompson - 25 mins ago  » 
    Like others have previously commented I have seen occasional picture break up and pixellation issues. I too initially thought it was maybe an RF signal quality issue, but given I have multiple DTV devices in the house fed from the same distribution system was mystified as to why. Checking the signal strength for each mux on this box they are between 66 and 82, all with 100% quality. The COFDM signal is generally pretty robust so unless there was interference either external or internal to the box it ought not to be the culprit.
    What I have started to notice though and verified when it happened last night is that I was watching the recording effectively in "live pause mode". That is the programme was being recorded whilst at the same time I was watching it. I had pressed pause for a few minutes and then continued watching. Several times during the programme there were brief bursts of pixellation. When I watched the recording back again today at the points where the errors were, the recording appeared fine. That seems to rule out signal issues as being the cause in my case.
    It makes me wonder therefore if there could be hard disk/filesystem issues which mean that occasionally the playback buffers cannot access data quick enough. Last night I was recording 2 HD streams and playing back 1 HD stream. I would hope that if I'm recording a channel, watch it and then press pause that it uses the stream its already recording rather than starting a new "Pause Buffer". Otherwise that could be 3 HD streams to record.
    Just wonder if this could be the same scenario where others have observed picture break up. Don't know whether it is then related to number of record streams, time delay etc.

    Interesting. I will setup a recording test tomorrow . Pretty sure that does not happen. Done this many times. One thing I have noticed. I have all my kit connected to a AVR. I can select a different source box while the Aura is paused.

    That means the box loses handshake. On returning to the aura input. the pause has been released and playback returns to the beginning. The recording buffer is complete. You just have to skip forward to where you stopped viewing.

    Doing the same with the other two boxes and pausing between a HDR-1000S and FVP-5000T, reselecting the input finds the content remains paused at the point the alternate input was selected.

    Anyone with a TV with different boxes selected to different HDMI inputs could try the same experiment. I only have one HDMI cable from AVR to 4K TV.

    | Fri 15 Jan 2021 21:22:50 #2 |
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    howarp

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    Like others have previously commented I have seen occasional picture break up and pixellation issues. I too initially thought it was maybe an RF signal quality issue, but given I have multiple DTV devices in the house fed from the same distribution system was mystified as to why. Checking the signal strength for each mux on this box they are between 66 and 82, all with 100% quality. The COFDM signal is generally pretty robust so unless there was interference either external or internal to the box it ought not to be the culprit.
    What I have started to notice though and verified when it happened last night is that I was watching the recording effectively in "live pause mode". That is the programme was being recorded whilst at the same time I was watching it. I had pressed pause for a few minutes and then continued watching. Several times during the programme there were brief bursts of pixellation. When I watched the recording back again today at the points where the errors were, the recording appeared fine. That seems to rule out signal issues as being the cause in my case.

    It makes me wonder therefore if there could be hard disk/filesystem issues which mean that occasionally the playback buffers cannot access data quick enough. Last night I was recording 2 HD streams and playing back 1 HD stream. I would hope that if I'm recording a channel, watch it and then press pause that it uses the stream its already recording rather than starting a new "Pause Buffer". Otherwise that could be 3 HD streams to record.

    Just wonder if this could be the same scenario where others have observed picture break up. Don't know whether it is then related to number of record streams, time delay etc.
    -------------------------
    I can confirm I get the same random pixelisation in live pause mode but if I play back the same section after the recording has completed the play back is perfect.I hope any future software update resolves this issue as the latest update has not.

    | Fri 29 Jan 2021 6:29:58 #3 |
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    Martin Liddle

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    howarp - 4 hours ago  » 
    That is the programme was being recorded whilst at the same time I was watching it.

    You haven't made it clear whether you were playing back the recording (what is usually called chase play) or just watching the recording live?

    I had pressed pause for a few minutes and then continued watching. Several times during the programme there were brief bursts of pixellation. When I watched the recording back again today at the points where the errors were, the recording appeared fine. That seems to rule out signal issues as being the cause in my case.

    I agree the signal levels are well below the levels where I would suspect tuner overload and your observation confirms that is isn't a signal strength issue.

    It makes me wonder therefore if there could be hard disk/filesystem issues which mean that occasionally the playback buffers cannot access data quick enough. Last night I was recording 2 HD streams and playing back 1 HD stream.

    On the earlier Humax PVRs the hard drive is easily capable of dealing with that workload. Do we know what make and model of hard drive is fitted to the Aura? Again on earlier models the bottleneck is the chip set used which is chosen to cope with the normal peak load but not have much performance margin.

    I would hope that if I'm recording a channel, watch it and then press pause that it uses the stream its already recording rather than starting a new "Pause Buffer". Otherwise that could be 3 HD streams to record.

    Again I can't speak for the Aura but on earlier Humax models it would be using the recorded stream rather than a buffer.

    Just wonder if this could be the same scenario where others have observed picture break up. Don't know whether it is then related to number of record streams, time delay etc.

    Some testing would hopefully show what is critical. If you could find a test case that reliably reproduces the problem then I suspect that would be very useful to the software developers.

    | Fri 29 Jan 2021 11:01:42 #4 |
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    howarp

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    At last I think I’ve fixed my random picture pixelation problems. Very brief (approx 1 sec) and random picture pixelation was affecting my Aura output. Finally fixed by using a variable attenuator - initially the signal strength was up to 96% with 100% signal quality, then after reducing the signal until the signal quality fell below 100% then increasing it slightly back up to 100% this reduced the signal strength down to 58% - so the Aura tuners seem extremely sensitive and may overload very easily.

    | Sun 31 Jan 2021 10:13:43 #5 |
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    Martin Liddle

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    howarp - 2 hours ago  » 
    Finally fixed by using a variable attenuator - initially the signal strength was up to 96% with 100% signal quality, then after reducing the signal until the signal quality fell below 100% then increasing it slightly back up to 100% this reduced the signal strength down to 58% - so the Aura tuners seem extremely sensitive and may overload very easily.

    I would suggest increasing the signal strength a bit more to say 70% to have some margin.

    | Sun 31 Jan 2021 12:22:56 #6 |
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    Geoff Thompson

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    Back to the original topic.
    This occurs in what some might call "chase play mode", but to me as I am previously used to Sky, I would call "Live Pause".
    Generally I am watching with a relatively short delay when I have seen this, probably no more than 5 to 10 minutes.
    The fact I am recording the channel at the time may be co-incidental but it provides the proof that it wasnt the signal. I think today I noticed it whilst just in the "live pause" mode, and when I skipped back, it then played OK.
    I have tried to re-create, using extremely short delay, a couple of seconds, as I thought that may exacerbate the problem. However as it may only occur a couple of times in an hour long programme, its a lot of time to spend just to re-create it. Its a brief break up in a small area, so blink and you might miss it.
    As Im usually watching in HD, and thats the only time I've seen it, I wonder if some of the additional process such as file encryption, decryption may also be at play or maybe its the file system and block sizes.
    Unless there is something up with my hard drive, I'm surprised that no one else has noticed this.

    | Sun 31 Jan 2021 20:48:02 #7 |
  8. grahamlthompson

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    Geoff Thompson - 1 hour ago  » 
    Back to the original topic.
    This occurs in what some might call "chase play mode", but to me as I am previously used to Sky, I would call "Live Pause".
    Generally I am watching with a relatively short delay when I have seen this, probably no more than 5 to 10 minutes.
    The fact I am recording the channel at the time may be co-incidental but it provides the proof that it wasnt the signal. I think today I noticed it whilst just in the "live pause" mode, and when I skipped back, it then played OK.
    I have tried to re-create, using extremely short delay, a couple of seconds, as I thought that may exacerbate the problem. However as it may only occur a couple of times in an hour long programme, its a lot of time to spend just to re-create it. Its a brief break up in a small area, so blink and you might miss it.
    As Im usually watching in HD, and thats the only time I've seen it, I wonder if some of the additional process such as file encryption, decryption may also be at play or maybe its the file system and block sizes.
    Unless there is something up with my hard drive, I'm surprised that no one else has noticed this.

    I regulary record up to 4-HD channels at the same time (never -SD) . However due to having a oled TV which are prone to screen burn from static images I turn off the screen when paused for a long period (not the TV the LG oleds can turn off just the display). Generally the same static image is shown on the kitchen LCD TV during a meal.

    Not seen any image breakup but the kitchen TV is a Full-HD display not a 4K one.

    | Sun 31 Jan 2021 22:18:55 #8 |
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    Martin Liddle

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    Geoff Thompson - 4 hours ago  » 
    Unless there is something up with my hard drive, I'm surprised that no one else has noticed this.

    Certainly it is true that if the hard drive is reallocating sectors then you see a very distinctive blip on the screen. I think I still favour the idea that something is struggling when the box is busy.

    | Mon 1 Feb 2021 1:50:48 #9 |
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    Geoff Thompson

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    So last night we were watching The Serpent on BBC 1 HD which started at 9pm and at the same time recording ITV HD. We paused the programme for about 10 mins and then started watching, so with about a 10 minute delay buffer. I think I noted over a dozen times where the picture glitched, randomly spread throughout the programme. Each time I made a brief note of time and scene so I could review on the recording today.
    As expected the recording appears perfect, no glitches.
    One other strange occurrence last night was that about 15 minutes before the end the programme glitched and seemed to jump a scene. What I shortly discovered was that it had jumped back to real time without intervention, as we reached the end of programme before expected. We then had to rewind to watch the missing 10 minutes.
    Its strange that if I try to recreate this effect during the daytime it never seems to happen. It only seems to happen on programmes I'm intent on watching which are often in the 9pm slot, so wonder if theres anything related to additional stream content these may carry such as audio coding type or audio description channel.

    | Mon 1 Feb 2021 17:30:27 #10 |

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