Discontinuities on HD Recordings

[Timtam]

Hello,

i'm currently facing off against a strange problem happening using the latest DVBLink Server + TVSource + TVAdvisor for Synology 415Play (some 6.0.0 build) and HD recordings. I'm using a DVBSky 960 CI as a tuner and so far it works well. I never tested it on another system so I can't say if the device itself is the problem, but since SD recordings work well... anyway, here's what's happening.

Well, kind of easy, as soon as I start HD recordings I encounter discontinuities, no matter if I visit the monitoring page or not. But if I visit the monitoring page, I can see them, they happen unforeseen and the encounter rate differs from recording to recording, but always multiple at once, starting at 4 at the same time, up to 31, totally random, as far as I can say. Sometimes there is just one moment where those discontinuities occur, sometimes they occur 5 or 6 times in one recording, but I never got one HD recording without any discontinuity at all. I can also say that SD recordings work without any problem at all, they run smoothly and do not have any errors or disconts at all. I'm checking the recordings afterwards using TSDoctor, which is also partly able to repair those failure, even if losing frames of course.

Anyway, I checked out a lot. I thought it might be the usb speed and switched the device from the USB 3.0 hub it was connected to into the 415Play itself - nothing changed. I tried plugging it into the USB 2.0 port of the 415Play and also into the 3.0 port - also, no difference. I checked the CPU state while recording and tried checking it while the disconts occurred - nothing strange here (always around 10% CPU usage). I thought it might be the HDD write speed which lacks the relevant transfer speed but honestly, I'm using a 4-drive RAID 5 with 4 8 TB Seagate drives with around 5400 rpm, it can't happen that those drives don't make the 15-20 MBit/sec write speed, at least I didn't do anything else on the device, so this shouldn't be the case, or do you think that this should be the problem? Anyway, even if the HDD should lack speed, the RAM should cache the data until writing is possible again, shouldn't it? That led me in testing recording with the Synology feature HDD write cache enabled and disabled - both didn't help (I at this moment disable write cache since this seems to have problems with RAID 5, or at least my seagate drives).

I also unplugged the power cord of the 960 CI, waited a bit and plugged it in again to make sure it isn't a problem with the 960 CI itself, no luck for me. I'm not sure if HD recordings ever worked for my system constellation. I have this 960 CI for half a year now and I use it quite often, but more or less only for SD recordings, that's why I encountered this problem just now and not lots earlier.

Well, now's the point I hit a brick wall and don't know where to turn next. That's bad since I planned to equip my 960 CI with a HD+ card to even watch private HD programs in the next week, but if I can't record them properly this seems a bit unnecessary to me...

Just to add, I don't know if the streaming works, since I don't Live TV very often (my server's main purpose is to record stuff while i'm not at home or don't have time).

Anyway, to show you what I mean I started a recording spontaneously at 5:40 PM today and attached you the log file, so you can guess whats happening. Any hints what I can try to make this work? Thanks.

Best Regards.
Timtam

[the_man]

Just in case - make an update of the dvblink server:DVBLink Server Version: 6.0.0 Build: 13314

May be useful:
http://forum.dvblogic.com/viewtopic.php ... nt#p111128

[Timtam]

Hi and thanks for your answer,

I looked for the version number and thought 6.0.0 equals 6.0.0, so I didn't update my DVBLink - until now. I downloaded the latest version from dvblogic.com and installed it via manual installation.
Now DVBLink Server shows the latest version, but TVSource and TV Advisor build numbers didn't change. Do I have to update them too, and if yes, how should I do that?

Anyway, I instantaneously started a new test recording, without restarting my whole box, but the update process restarted the DVBLink Server anyway, and I encounter the same problems as before.

Do you think it would help to restart my server completely and try again, or should this be enough to detect that the update didn't help? Or do I need to update TVSource too? Or might something else cause the issues?

Anyway, thanks for reading into my problem.

Best Regards.
Timtam

[Timtam]

Update:
I updated TVSource through the DVBLink package manager up to the build number the DVBLink Server has too and afterwards restarted my whole server system and started a new test recording. Same results here, until now one time 11 disconts and 5 secs later again 21 disconts. Stopped checking the monitoring page constantly.
I also removed all unnecessary packages yesterday, including VPN Server, WebDAV Station and all that kind of unused stuff laying around sleeping on my box, but this didn't help, obviously.

I attached a log with the newest record log data.

[the_man]

It would be great for you to test the dvblink server on PC - just install the desktop version with the trial license, configure tuners and check results. With such test you will exclude the NAS influence.

[Timtam]

Yeah, will do this at the beginning of next week, since i'm not at home over the weekend. Thanks in advance. Also i've got a second tuner inside of my windows pc, so if I install the dvblink server for windows I can test it with this tuner too too, so we can see if it's the tuner hardware which matters here. Thanks anyway, will post back asap.

[Timtam]

Hi, it's me again.
Two short test recordings (7 and 16 minutes) proofed to be errorless on windows, which means that the tuner isn't the actual vault, but the NAS seems to be the problematic device instead. It will be some configuration thingy, do you have some hint what I can check out to fix this up? Thanks.

[the_man]

Really hard to say what you may try next, as you have checked mainly all possible causes...
So, then same cables/connectors works great on the server for desktop.

Lets make a new log files, i'll check them maybe there will be some answer.
Just restart the DVBLink server, remove the HD channels from the Channels selection list and rescan transponders once more. Then add required channels and play or record them in order to reproduce the issue, after what make and attach new log files.

[Timtam]

Hi,

thanks, I did just as you said. Restarted the whole NAS, removed all HD channels from my channel list, rescanned all transponders, added just the Das Erste HD channel to the channel list again and started a Test Recording.
Encountered the expected disconts after aprox 30 secs or so, and after this again 30 secs later the next ones. Stopped looking onto the counter and stopped the recording manually 15 mins later.
Hope that helps. Will receive a Raspi 3 tomorrow and try to check the TV tuner on this one. If we don't get the tuner to work under the NAS, maybe I will use this Raspi as TV Server instead. Anyway, will do my best to help finding this error.

Thanks for your assistance. Log file attached.

[Timtam]

Just found some of these lines in the log, anyway, they don't appear the same amount of times I encounter disconts, but maybe they give some hint into the right direction?
2017-Jan-18 18:14:54: [E] can't read from dvr for tuner 8, dvr 0, err 75

So, what does err 75 mean? Or do those lines just appear because the tuner is currently busy recording while the server is updating the epg data?
Might this problem have something to do with the antenna cable? that's the only cable I switched when testing the tv tuner on my windows pc, since I had to move rooms to do that. But in this case it would be some kind of unlogical, since SD recordings are totally discont-free...

Until then.

[Timtam]

okay, honestly, that's absolutely strange. Well, it recorded HD channels fine down in my room here without any discont, but even the Raspi 3 (OpenELEC 7.0.1 with newest DVBLink Server/TVSource) above, where the NAS resides, gets disconts when recording HD channels. The only things different down here are/were:
1. The antenna cable used is different, since I didn't take this one with me.
2. Above i'm using a USP, where the S960 CI is attached to, down in my room it was just attached directly to the power without a USP in between.

So, maybe the antenna cable is somewhat broken, but this would mean that also SD channels should be affected, shouldn't they?
Or, the other option, the USP somewhat has problems forwarding the power so that it happens that the tuner doesn't get enough power sometimes which results in package loss or something... i'm no specialist in power supply things, but yeah, these are the only two things possible, unless the DVBLink Server has some serious troubles under Linux which don't occur under Windows at all.
I will test again at the beginning of next week with my Windows Laptop to check if it really doesn't invoke disconts and check back here than. Maybe you have some other idea until then.

Best Regards.

[Timtam]

And yeah, what should I say, it's me again.
After talking to my father, who works as a service worker for a TV and Internet organisation, I might know the answer.
The TV tuner is standing next to the NAS and also next to the USP and the router, which means, that some of the devices up there seems to emit some kind of radiance which influences the tuner, but only some frequencies. At least it can be the router itself with it's 2,4 GHZ WiFi band.
I tested out:
Das Erste HD - some random disconts
Das Erste SD - again, some random disconts
ONE HD (same transponder as Das Erste) - again, some random disconts
ZDF HD (another transponder) - nearly only disconts, hard to catch a moment without any disconts shown on diagnosis panel
ServusTV HD (yet another transponder) - less disconts as ZDF, but more than Das Erste.
Other transponders, like Sat.1 or ProSieben (should be same transponder) don't show any disconts at all. Therefore it must be something frequency-related.
That also explains why it all worked fine down here in my room, the walls reduced the emission so it won't harm the tuner at all.
So, now I'll have to test a bit more (other transponders and stuff), and maybe also test the recording without the router running so that I can check if it is the WiFi which causes the trouble here.
Anyway, that's bad at all, do you know some way to protect my tuner against it? It's funny, the tuner already consists of a shell of metal, I thought that this metal would protect the tuner from such influences, but this seems to be totally wrong.
Did you hear of something like this before?
Of course I don't guarantee anything, it might also be just some crazy idea flowing around in my mind. I will post back after some more serious testing.
Thanks.

[the_man]

Really interesting, and yes - i have faced with similar issue.
The issue was that channels/ sometimes - all / sometimes - a few of them - were totally corrupted and not usable for watching. And all of that were due to the 4G antenna which was set-up not far from the house. The issue was solved with a new expensive coaxial cable.

[Timtam]

Hi,

I just noticed I've forgotten to tell my final solution here.


I wasn't able to finally solve my problem. I moved my TV device into a different room, attaching it to a raspi 3 and all works fine now. I still don't know the real issue in this other room, but the antenna guy can even see the interferrences on his validation device, so any device up there (USP or whatever) seems to cause trouble with the antenna signal.

Anyway, thanks for your help.

Best Regards.
Timtam