Stuttering on DVB-T channels. Record service cures issue....for a while.

[shaunpatrick77]

I'm getting bad stuttering after a day or so, but only on DVB-T. It affects both live tv and any recordings made while the issue is prevalent.

I've ruled out signal or codec issues, especially as a restart of the recording service instantly cures it. I then get rock solid live tv and recordings until the issue returns, usually 24-48 hours later. A restart of NPVR doesn't help. Channels coming through my Colossus aren't affected. I've also tried two totally different tuners, one a PCI and one an external USB, both different makes, and it made no difference.

In the logs you can see live tv starting at 2015-04-11 19:43:45 to 2015-04-11 21:24:18, that was stuttering badly.
I restarted NPVR to no avail, and then I restarted the recording service, and it was perfect.

I've also noticed that a lot of extra cpu use at idle during the issue, and that drops to next to nothing on the recording service restart.

Any help would be appreciated

Just realised that the heading should read "recording service restart cures it ...for a while"

[shaunpatrick77]

Ok, no replies, so can anyone tell at least tell me if a "Renew lease ok (0x1C0013)" every 10 seconds in the Nrecord log is normal behaviour?

[Reddwarf]

I'v had a look at your logs and I can't see anything out of the ordinary. Could it be an issue with buffering on the harddrive? Do you defragment reguarly? What about the signal level to the tuners? I think you'll hvae to look for the problem outside npvr...

[johnsonx42]

yes, the "renew lease" messages are normal during live tv.

use process monitor to determine which thread is causing the high CPU utilization.

https://technet.microsoft.com/en-us/libr...2147217396

[sub]

I'm getting bad stuttering after a day or so, but only on DVB-T. It affects both live tv and any recordings made while the issue is prevalent.

So it also affects playback of recordings? This make me think it's just a playback issue, with the specific audio decoder you're using, or the audio renderer. ie, if you try playing the recording in VLC, does it have the same stuttering? I'm guessing you'll get good audio there.

When it comes to digital recordings, if you've got a good picture, then the stream is largely free from any signal corruption, so will also have a good audio stream. ie, NextPVR does not process audio separately while recordings, it's pretty much just a dump of the broadcast stream, so good video also means good audio.

[shaunpatrick77]

The stuttering is audio and video. I'll check recordings with VLC next time it happens Sub, but I'm guessing it's still there.
Maybe I'm missing something here but I can't see how its a codec or signal issue if a restart of the Nrecord fixes it instantly it with no other change.

I guess it could be tied up with hard drive buffering, perhaps the lower .264 bit rate from the Colossus doesnt stress the system as much. But I even have a separate timeshift drive to avoid this.
It is an AMD 7 series chipset which can have AHCI problems. I guess I have to move to a new motherboard/CPU if all else fails....

[shaunpatrick77]

Also, given that a rebuild is looking a certainty, what's the current recommend OS? Is there any benefit of Win 8 over 7 for NPVR? 64 or 32bit?

Thanks for taking a look at my logs btw.

PS a check of the recording drive shows no fragmentation.

[Reddwarf]

I would definitely go for 64 bit, but for npvr I can't see win8 having any advantages over win7, on the contrary actually since some MS decoders won't work for npvr in win8.

[sub]

The stuttering is audio and video. I'll check recordings with VLC next time it happens Sub, but I'm guessing it's still there.

I'm happy to take a look at one of these problem recordings for you, if you can put one somewhere I can download it from. It'd have to be a relatively short recording, maybe up to 1GB. You can cut down a longer recording using the cutchunk utility in the wiki.

[shaunpatrick77]

Hi Guys
I've done a lot of work on this, and have come across an interesting discovery.
Here's a quick summary, please bear with me.

I've upgraded basically all hardware (MB, CPU, Boot SSD, Live TV buffer drive, DVB-T tuner and memory) and have done a scratch build with Win7 64.
During the test phase I was just using DVB-t on the bench and had zero issues over several days. ie very low cpu usage, 100% clean video and perfect test recordings.
Satisfied, I swapped in the new system and also added the Colossus in for cable.

After an hour of testing, and much to my disbelief and horror the issue returned, ie stuttering on DVB-T. I checked the idle cpu (which had been basically zero during testing) and sure enough it had climbed. Restarting nrecord from the tray settled the cpu back to zero and DVT-t video was perfect again. I was back to square one, but at least I could rule out hardware & drivers.

After a few minutes of profanity I had an idea. Maybe it was the something to do with the Colossus. I've carefully noted that each time I start live tv via the Colossus I get a slight increment in idle CPU use. After about 10-15 channel changes its gets to the point where it affects DVB-t. If you keep going to with channel changes you can really get very high cpu use build up, to the point that the machine slows in general responsiveness. Eventually it begins to affect the video stream from the Colossus, but DVB-t is the first to go.
As usual a restart from the tray fixes it instantly and completely.

I've tested starting and stopping the card from the hauppauge capture app and it has no build up effect on CPU use.

Also, if I un-tick 'restart live tv on channel change' I can do numerous channel 'on the fly' changes without the build up. However, changing to DVB-t or stopping live tv to return to a menu will again cause the issue.
Therefore, with my limited knowledge, it appears to be related to the number of times a graph is created for the Colossus, almost like its not being cleared out properly and it then begins to build up and consume more resources the more the channel is changed. Whatever it is, a restart from the tray clears it.

I've tested this to death and can reproduce it at will. Looks like the DVB-t stutter was just a symptom of an issue with the Colossus.

I haven't posted and logs as I would assume they will still show nothing like last time.
Cheers.

PS I've also noticed this thread http://forums.nextpvr.com/showthread.php...ot-of-data
And it seems to be related as a nrecord restart seems to cure that too.