HD playback breakup and auto-decrypt failures

[hairy_mutley]

Thought I would try a real test the other night...
Set detect detectads to chaserun mode, record one channel (SD) and watch a different recording. The result was picture breakup during replay! Obviously I wondered if it was having any effect on the recording so I switched to watching the recording (in chase) and could see breakups there as well. Looking again later, it appears that at least some of the breakups were present in the recording.
It does seem that I can only safely run detectads while the system is not recording.

I have a strong signal, so breakups do not occur on the live signal; I can stand on the back lawn and see the transmitters lights at night (according to UKFreeTV, Mendip is 317 degrees, 34.9 km).
The disk is OK, fixdisk reports nothing, nor does the long disk test.

 

[MymsMan]

While I have problems with HD channels I routinely (at least twice a day) record two SD channels simultaneously with at least one of them processed by chaserun and often watch another channel or recording at the same time. I rarely see picture breakups of SD recordings.

If there are going to be problems they will occur occur during the original recording, capturing the broadcast stream and transferring it to hard disk has to be done in real time the humax can't ask the transmitter to slow down or retransmit frames!

Apparently too strong TV signals can also cause problems

 

[Black Hole]

Apparently too strong TV signals can also cause problems

Yes, if the input saturates and causes signal distortion. The ideal is to have the quality figure at 100 and the strength figure at 99 (it tops out at 100, so if the reading is 100 you don't know how far above "100" it actually is).

If the signal goes too strong the quality figure will dip, but you have to look at the signal detection screen (via the menus) over a period; the other places you can see the quality and strength figures are either instantaneous samples or don't stay up long enough.

 

[hairy_mutley]

While I have problems with HD channels I routinely (at least twice a day) record two SD channels simultaneously with at least one of them processed by chaserun and often watch another channel or recording at the same time. I rarely see picture breakups of SD recordings.

It is hard to understand what it is about my system that can be making it behave so much worse than others.
For now I will stick to manually starting detect ads when the system is not recording. But it is a pain having to launch each manually, which is why it would be nice to be able to use global with sweeper (open sweeper, enable the rule, run it and disable it again, job done).

If the signal goes too strong the quality figure will dip, but you have to look at the signal detection screen (via the menus) over a period; the other places you can see the quality and strength figures are either instantaneous samples or don't stay up long enough.

Mine is OK. At present it is 100% quality on all 8 mux (no LBS); signal is 85 to 90 on the mains and down to about 70 on COM7 & 8.
I will take a look at other times of day, but I don't expect it will get to the problem areas (it might weaken in the rain, especially as the aerial is in the loft)

 

[MymsMan]

It is hard to understand what it is about my system that can be making it behave so much worse than others.
For now I will stick to manually starting detect ads when the system is not recording. But it is a pain having to launch each manually, which is why it would be nice to be able to use global with sweeper (open sweeper, enable the rule, run it and disable it again, job done).

I am part way through the coding to allow for scheduling when DetectAds runs, I just need to find an opportunity when not baby sitting granddaughter and cat is not sitting on my arm or keyboard.

 

[Owen Smith]

Yes, if the input saturates and causes signal distortion. The ideal is to have the quality figure at 100 and the strength figure at 99 (it tops out at 100, so if the reading is 100 you don't know how far above "100" it actually is).

If the signal goes too strong the quality figure will dip, but you have to look at the signal detection screen (via the menus) over a period; the other places you can see the quality and strength figures are either instantaneous samples or don't stay up long enough.

Strength 99 is too high. Signal strength goes up and down all the time due to atmospheric changes, rain, changes at the transmitter, all sorts of things. If you see it at 99 then it will inevitably go over 100 at some point when you're not observing it. Personally I like to keep signal strength below 90 so it is well clear of any risk of saturating the receiver.

I receive COM7 and COM8 at signal strengths in the low 60s and they're absolutely perfect. I watch a lot of BBC4 HD and there are no glitches at all on it. High signal strength is over rated, all you need is enough signal strength.

 

[Black Hole]

I'll agree that I should have said 99 maximum is ideal. If we agree saturation does not occur dead on 100, but we don't know how much headroom there is, if the fluctuations in signal never exceed 99 you still have the maximum margin to not having too little signal - which is not to say that 60 is not perfectly OK.

 

[MymsMan]

I am part way through the coding to allow for scheduling when DetectAds runs, I just need to find an opportunity when not baby sitting granddaughter and cat is not sitting on my arm or keyboard.

I have finally, sorry for the delay, got round to uploading this support

If you wish wish to defer DetectAds processing to a time when the system is less busy you can specify a target start time.
The target time is the earliest start time but processing may start later depending on when the regular DetectAds task starts and how many other items need to be processed on the queue. You must of course ensure the the system is switched on at the target processing time and remains on long enough to process all of the queued items (possibly set up a scheduled repeating reminder event)

The target time can be specified on the settings page, DetectAds processing panel or as -t hh:mm on the Sweeper action parameter or on command line invocation

 

[grahamlthompson]

Yes, if the input saturates and causes signal distortion. The ideal is to have the quality figure at 100 and the strength figure at 99 (it tops out at 100, so if the reading is 100 you don't know how far above "100" it actually is).

If the signal goes too strong the quality figure will dip, but you have to look at the signal detection screen (via the menus) over a period; the other places you can see the quality and strength figures are either instantaneous samples or don't stay up long enough.

Distortion of the carrier caused by signal clipping causes the indicated signal strength to fall if it's extreme (In this case applying attenuation actually increases the indicated signal strength). Best indication is the quality value fluctuating widely.