Live TV stutters every 6 minutes

[peterbonge]

Hello,

I'm new to NextPVR and I already got Live TV working, but the playback stops/stutters for 1-3 seconds every ~6 minutes.
Now I've watched the hard disk with the buffer folder with the task manager. The first buffer file gets written continuously with about 0.5-1.0 MB/s. Then a new file gets written and the write speed drops to about 50 KB/s. After 6 minutes the hard disk activity jumps to 100% and at this time the playback stutters.

So why doesn't the app continue to write the buffer continuously after the first file?

My system:
i5 @ 3.00 GHz, 8 GB RAM
Win 8.1 with MC, 64-bit
Seagate ST950032 USB Device (for the buffer), NTFS formatted
AVerMedia A827 USB Hybrid (TV card, analog)


Regards,
Peter Bonge

[mikeh49]

Try disabling EPG update during live TV. I think it is in Settings. This has helped others who were using the EPG data provided from the TV channel. If indeed you are watching analog TV, this probably doesn't apply.

The problem might be the USB drive for the buffer; there might be an issue with the USB system in the switch between buffer files. I don't think I've heard of anyone using a USB drive for this.

[peterbonge]

You mean "Auto Update EPG"? That's already switched off.
And yes, I'm watching analog TV.

I'm using an external USB drive because I don't really want continuous writing on my internal SSD drives.
And the WMC doesn't have any problems with continuous writing on the external USB drive.
Maybe I'll try one of the internal drives. Or what about a folder on my NAS?

[johnsonx42]

in Settings->Misc try switching the Timeshift Mode to EPG-based. It won't completely solve your problem, but it will only switch buffer files when a new show starts rather than every 6 minutes.

as to the problem itself, it's going to be something peculiar to your system, likely having something to do with using the USB drive. No one else has ever reported a problem like this. Keep in mind NextPVR doesn't write to your USB drive or any drive, all it does is say "hey Windows, here's some data that belongs in a file... you go write it".

I'd think an SSD would be a great place for the live tv buffer, unless you really watch live tv a LOT. I can't see a couple of hours a day being a problem for most SSD's unless it's a particularly old or small SSD.

[peterbonge]

EPG-based: I'm not using EPG at the moment, because it's not really easy to set up, especially with an analog signal.
So what would be the result if I would switch to EPG-based?

I've just tried it with a SSD. The playback is fine now, but the write rate still goes down after the first file. That is strange. I can't see peaks at the end of the files, but I think this is because of the high write speed of the SSD.

[johnsonx42]

with the timeshift engine in EPG-based mode, it only creates one timeshift file per TV show, so you'd presumably only get the stutter every 30 or 60 minutes, and only between shows when it shouldn't matter. I don't know what NPVR would do if you ask for EPG-based live tv, but don't actually have any EPG data setup.

If you'd like good EPG data for analog, see here: http://forums.nextpvr.com/showthread.php...post487428 (you'll probably need the patch in post #3 of that thread too).

[mvallevand]

I have used a $90 SSD for my backend for a while now and watch a lot of live tv (in the fall) and the health is stiil very high with estimates of more than a decade of use ahead of me and that is with Vista and I don't even have TRIM support. If the monitors show it starting to fail I'll spend another $90.

The stuttering isn't just transition from show to show, the decoder needs to read enough to not stall during peaks. If you pause 20 seconds do you still get stuttering? That might be the USB interface.

There is also a registry setting to increase the slip file size. to as high as you think you need.

Martin

[christheman]

Here is a problem I had and how I solved it. This may or may not pertain to your issue software-wise, but maybe hardware-wise.

There was an issue I had with USB drives. In particular, the laptop-sized 2.5" hard drives were underpowered. The computer was not able to provide a solid voltage to it through the USB port. So I dug up an usused powered USB hub out of storage (one with its own AC transformer) and plugged the USB HDD into that. Problem solved.

If underpowered, another solution might be to use externally powered drives, such as the 3.5" Western Digital MyBook drives. Those work wonderfully on the machine I had a problem with. I use those for archiving, but the fact that they have their own power source solves that problem for me. (worst case scenario for an underpowered external HDD is you lose all your data - yikes)

Last but not least is to just use the internal HD. That is what I actually do on my NPVR computer.

The other hard drives have to do with transferring the files to another computer so I can run VideoRedo and process them without disturbing NPVR. I transfer during times when NPVR is inactive. I use the smaller 2.5" USB-powered HDDs for the actual transfers. Then after the VideoRedo processing work is done on the second machine, I move the finished product to the powered 3.5" Western Digital MyBook HDD to store for an indefinite amount of time.

[peterbonge]

Here I don't think that it is a power problem. It's just a speed problem because it's a slow USB 2.0 drive.

Yesterday I've tested it with a really fast USB 3.0 memory stick (SanDisk Extreme). This stick is like a small SSD drive and it is shown as a hard disk and not as a removable drive.
But that didn't work. It seems that a write speed of 100 MB/s isn't enough.

I'll continue to use the internal SSD, but it would be nice if the basic problem would be solved. Continuous writing without peaks of >150MB/s would certainly be good.

If I would increase the the time/file size the stuttering should happen less often, but the stuttering could be heavier, right?
What about decreasing the time/file size? That would mean less data to write when switching the files, right?

[christheman]

Here I don't think that it is a power problem. It's just a speed problem because it's a slow USB 2.0 drive.

Yesterday I've tested it with a really fast USB 3.0 memory stick (SanDisk Extreme). This stick is like a small SSD drive and it is shown as a hard disk and not as a removable drive.
But that didn't work. It seems that a write speed of 100 MB/s isn't enough.

I'll continue to use the internal SSD, but it would be nice if the basic problem would be solved. Continuous writing without peaks of >150MB/s would certainly be good.

If I would increase the the time/file size the stuttering should happen less often, but the stuttering could be heavier, right?
What about decreasing the time/file size? That would mean less data to write when switching the files, right?

If you still have the NPVR cache settings set to 6 min, and it is doing this once every 6 min?? The file opening/file closing may require more power to the HDD. If you have a powered USB hub sitting around, go ahead and give it a try using it as a power injector. If you don't then you will never know. No changes need to be made to the system. Just plug it in and try it.