Fragile recordings

[liteswap]

Is it me (as a relative newbie to DVB-S - I've been happily using GBPVR for analogue for three years) or is the digital recording process fragile?

What I mean is that when starting or pausing playback, or doing much else that involves a fair amount of IO, disk activity jumps and any ongoing recordings can not only show horrible pixellation, they quite often break. This means they're unplayable after the point in time when I paused or started playback of that or another recording. I lost the first 20 minutes of last weekend's F1 race that way (no great loss, some would say )...

My PVR PC is fairly low-specced for energy/heat reduction purposes but this does not seem to be a CPU-related but an IO-related issue. So the question is: has anyone else found this, and/or found a fix or amelioration?

One thought: is maybe the fact that both DVB-S tuners are on the PCI (not PCIe) bus an issue here?

Thanks again for the application of all this GBPVR experience and brainpower...

[martint123]

I can't say I've seen anything like that with DVB-S or DVB-T except when I had the occasional disk problem and windows defaulted to PIO mode rather than DMA mode. This seems to happen if there are a number of IO errors and it stays in DMA mode until something is done about it. It gave similar symptoms to those you mention.

I can't see the PCI bus and more than one tuner on the PCI bus being a problem - all mine are on the PCI bus and not showing a bottleneck.

[sub]

I havnt seen that here either, or any reports to make think there is a problem on this front. Its more likely a I/O or latency issue, rather than a problem with the recording process.

[mvallevand]

Where I see a major disk i/o bottleneck is after playing HD livetv on the PCH there are huge delays of up to 20 seconds just closing the file and returning control. The PC even is non-responsive in this time.

Martin

[sub]

Where I see a major disk i/o bottleneck is after playing HD livetv on the PCH there are huge delays of up to 20 seconds just closing the file and returning control. The PC even is non-responsive in this time.

It wont be related to this thread problem (I/O problems during recording), but if you post the logs for your stopping live tv on PCH problem, I'll check what its doing or where the delay is occurring.

[stustunz]

liteswap what do you record in dvrms, ts or mpeg ?
i used to have something similar when using mpeg/cyberlink mux
dvrms was good
i have found ts to be way better

make sure you have a excelent signal strength

if you play the recordings on another device/software do they play ok

[pBS]

i'd say it's your low cpu power....cpu handles a lot of disk io duties, and yours doesnt have much cache or grunt, so it may be letting you down on the disk front...
but it's mostly io throughput issues...you should be able to handle plyaing one while recording one hd stream fine,anything above that will give that system problems tho...

plus, multiple recordings at same time to same disk leads to major fragmentation..which makes things worse yet...add comskip to that and a bit worse still...

it is advantageous to have 7200 rpm sata drives tho.. w/as much cache as possible..

one solution is to separate the recordings onto different drives...
i use ntfslinker to makes dir links to another drive so some recordings get recorded onto multiple drives same time, thus multiplying that throughput available...
[and keeping them unfragged too]
if you have multiple disks and want more info how to do it just let me know...
[pretty simple one time setup/dir really]
ntfslinker- http://forums.nextpvr.com/showthread.php?t=38189
but it only works on a series basis, meaning the whole dir gets moved, and future recordings of that show will go there too..

only other thing i can think of to help is faster cpu or moving each drive to their own controller..[ide type,one per cable]
but definitely check that it's in DMA mode instead of pio mode...that helps a lot..

[gEd]

liteswap: Funnily enough, I also missed a big section of the the grand prix last sunday, only in my case it was between laps 20 and 50. However, after studying the logs in detail I have finally concluded that it was not a problem with the pc or gbpvr but rather because I had fallen asleep...

I assume you are describing problems with SD rather than HD programmes?

On my old Athlon system, I could record 2 freeview programs whilst watching a third so unless DVB-S somehow taxes the system more that DVB-T, your cpu should be more than powerful enough - HD might be another matter.

If you are using an older style PATA (not SATA) disk, make sure you do not have any CD/DVDs connected to the same cable as the hard disk.

I assume you have defragged the heck out of the disk?

Buy a 1TB samsung F1 disk and see if that helps improve matters. You will need the space anyway when you start recording HD programmes.

[liteswap]

Thanks again all for the responses.

@stustunz:

liteswap what do you record in dvrms, ts or mpeg ?
i used to have something similar when using mpeg/cyberlink mux
dvrms was good
i have found ts to be way better

I've been using ATI MPEG as I've read here that it's the best way - although I have tried others in the past too, without much change in the outcome. I'll have another try with TS.

@gEd:

I assume you are describing problems with SD rather than HD programmes?

yes - SD only right now. This rig is not powerful enough to deliver HD - its one reason I'm considering an upgrade, although the narrow range of content available isn't quite compelling enough - yet...

If you are using an older style PATA (not SATA) disk, make sure you do not have any CD/DVDs connected to the same cable as the hard disk.

I assume you have defragged the heck out of the disk?

It's a fairly new SATA disk running in Ultra DMA 5 mode, and yes, it's gets defragged automatically every night for four hours. The disk itself is OK size-wise at the moment and the reason for buying it at the time (three years ago now) was because it's very quiet. I may upgrade it at some point - it's on the 'nice-to-have' list...

And from all other comments, it would appear that, unless I can fix it by using one of the other demuxes, the only potential fix I have is a mobo/CPU upgrade.

More expense: ho-hum...

[gEd]

well if it's a sata drive, then it should be fine. I can't see why u need to upgrade tbh.

perhaps your sata controller and dvb-s card are sharing an interupt.

run msinfo32 to find what interupts are being used by what devices.

make sure your mobo bios is up to date as well as the chipset drivers.

try removing the old analogue tuner and test then try moving the dvb-s tuner to a different pci slot.

as stu said, use ts mux.

btw: out of interest, when the defrag runs for 4 hours, does it complete?
i.e. is it still trying to complete a fulll defrag of a really badly fragmented drive or are u saying that every day, the amount of new and deleted recordings takes 4 hours to defrag? (which would seem excessive).

download and run hdtach disk benchmark utility. you should see roughly 50 and 45bytes/sec for average read and write speeds respectively, while peaking at 130.5 Mbytes/sec for burst speed.

did u set the disk to run in acoustic (quiet) mode using a utility from the manufacturer?