Bad stutter on TVNZ 6 & 7 (DVB-T,780G/HD3200)

Forums › Home Theatre (including HTPC and EPG Collector) › Bad stutter on TVNZ 6 & 7 (DVB-T,780G/HD3200)

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10 posts

Wannabe Geek

#170163 9-Oct-2008 14:42

i have just been messing around and rlevis is correct, only happens when watching live tv. recored tv is sweet.

even if i press "pause" then "play" dont even have to wait a second, the result is perfectly smooth tv. so even if the tv is timeshifed less than a second its ok.

rlevis - try that and see if that helps you. press "pause" then "play" and see if jitters.

anyone know if there is anyway i can set mediaportal to automatcally timeshift back 1 second all the time? or know why its doning this?

rlevis

355 posts

Ultimate Geek
+1 received by user: 33

#170948 13-Oct-2008 20:47

Yep. That fixed my problem too. Pause for a second and it's sweet. Playing from the timeshifted recording is good.

I actually noticed something similar on TV1 once where panned scenes were a little jittery. Paused for a second and this was gone too. I haven't seen this since on the HD channels.

I wonder where to go from here. The family knows know how to resolve it but it's not ideal. If MediaPortal could be told to always playback from 1 second previous then it would be sweet.

I updated MP to RC3 the other day and updated Cyberlink PowerDVD8 to the latest version, but same problem.

So in summary, the problem manifests when the same video being saved to the timeshifting folder is being viewed on the screen. It sounds like perhaps it is strictly a MediaPortal issue of some sort.

I wonder if disabling timeshifting also resolves this. I'm not exactly sure how to do that. Perhaps entering 0 files in the TV server config?

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#171018 14-Oct-2008 08:33

rlevis,

I posted a question a long time ago asking if the timeshifting can be deactivated, and I was told it cannot be done, it defeats the purpose of tv server and PVR system completely.

I cannot see a major improvement using the "timeshifting trick". Maybe it is there, but not as a major improvement. Maybe my system already performs well, and the existing jitter cannot be removed at all? That would be an awful outcome, as the jitter is more than visible.. it is really annoying. One of the worse one is the ad for Freeview, where the guy get a huge window-wiper out of his car. Just before that, there is a panning sequence from the tv, across the room, towards the door leading to outside, where we can see the guy struggling to get the over-sized squeegee out of his car. That panning is among the worst I encounter.

anyone else seeing that?

mobo Intel DH55PJ, RAM: 4GB RAM, Nova-T 500 HD + Avermedia Trinity tuner card, Geforce 520 video, 120GB SSD Sandisk + 640 WD + 1000SG, Win7 Home Prem 64-bit, Media Portal 1.15.0; BTC 9019URF Cordless Keyboard, Panasonic 55" (HDMI cable), HTPC Case Silverstone Grandia GD05B.

rlevis

355 posts

Ultimate Geek
+1 received by user: 33

#171062 14-Oct-2008 12:45

I use to see the same jitter on the HD Demo channel and all channels until I changed the graphics card to 50hz to match the broadcast frame rate.

Quidam

291 posts

Ultimate Geek

#171067 14-Oct-2008 13:21

Hi guys,
I was just about to comment on a similar issue I had when I was using SageTV. The partial solution (as you guys have found) is to jump back a second or two behind the timeshifting buffer and then you get smooth playback.

In my particular case, it was only happening when I was streaming to another PC.

Anyway, it seems to me that the issue may well be the performance of the hard-drive you are using to timeshift to.

So what are your HDD specs (and interface) Are you SATA or IDE?

If possible, I'd recommend you do not use your system (C) drive for the timeshifting buffer and see if that makes a difference.

Also, go to your device manager; select disk drives; properties then select the Policies tab. Ensure the "Enable write caching" checkbox is selected and see if that makes a difference.

Good luck

ps.

If the Write Cache buffer is already enabled try taking it off. Since I don't know the full details of how it works (eg. it may improve write performance but cause a lag with the read performance, assuming you are reading data that has not yet hit the hard-drive and is not available to be read directly from the write-cache -which I admit seems silly/unlikely)

"There is no way to Peace -Peace is the Way" (A. J. Muste)

rlevis

355 posts

Ultimate Geek
+1 received by user: 33

#171076 14-Oct-2008 14:12

I'm not sure HDD performance is the issue because the problem occurs only with TVNZ 6 and 7, and the TVNZ Sports Extra channels. None of the other SD channels are affected, and none of the HD channels. I did mention that I saw some jitter on TV1 once, but it looks like that was a one-off situation and may be unrelated. That one could well have been related to the HDD being busy at the time.

The drive is a new WD 750GB green drive with 2 partitions. The OS is on the C partition and the timeshifting, videos, music etc is on D.

Someone else built this PC for me, and even though the HDD and BD-ROM are both SATA, for some reason the BIOS is set to IDE mode for both, and they also show as being on the same IDE channel as master and slave. Switching the BIOS to SATA causes Windows to reboot just after booting. There doesn't appear to be any performce issue, but I have been meaning to open the case and have a look. I don't think this is related to the problem but who knows.

Write-ahead caching should always be enabled. I believe disabling it will slow down performance.

Ross.

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Quidam

291 posts

Ultimate Geek

#171081 14-Oct-2008 15:11

rlevis: I'm not sure HDD performance is the issue because the problem occurs only with TVNZ 6 and 7, and the TVNZ Sports Extra channels.? None of the other SD channels are affected, and none of the HD channels.? I did mention that I saw some jitter on TV1 once, but it looks like that?was a one-off situation and may be unrelated.? That one could well have been related to the HDD being busy at the time.

The drive is a new WD 750GB green drive with 2 partitions.? The OS is on the C partition and the timeshifting, videos, music etc is on D.

Someone else built this PC for me, and even though the HDD?and BD-ROM are both SATA, for some reason the BIOS is set to IDE mode for both, and they also show as being on the same IDE channel as master and slave.? Switching the BIOS to SATA causes Windows to reboot just after booting.? There doesn't appear to be any performce issue, but I have been meaning to open the case and have a look.? I don't think this is related to the problem but who knows.

Write-ahead caching should always be enabled.? I?believe disabling it will?slow down performance.

Ross.

Hi.

I'm going from memory here, but IDE Mode (as versus the physical interface) is fine and does not imply lower performance than if you were running in native SATA mode. What it does mean is that the O/S can't provide features such as hot-docking of sata devices, which comes from being able to use the NCQ (Native Command Queuing) from within the O/S, when it talks to your hard-drive.

I believe that once Windows has been installed, you cannot change the interface method, or else Windows will no longer be able to boot off your drive.

ps. As explained, my suggestion to "try" without caching enabled was based on a theory that a "write cache" does not necessarily imply it provides "read from cache" capabilities. If this is true (and it's pure guesswork on my part) then yes, a write cache will improve write performance -but may well cause a lag if you are trying to immediately read the same data before it has been physically written to the disk. My point being, it never hurts to try.

"There is no way to Peace -Peace is the Way" (A. J. Muste)

Quidam

291 posts

Ultimate Geek

#171088 14-Oct-2008 15:31

ps.

partitioning a single drive into 2 logical drives offers some benefits (like being able to define/format large allocation units for video storage on 1 partition and smaller units for the system drive) but obviously you are still using a single physcal drive; onboard cache and I/O channel -so if accessing data from both partitions at the same time there is still a potential bottleneck that would not exist if you were timeshifting to a seperate "physical" drive. However, I agree that it seems odd that it only happens on specific channels.

Regardless, I thought of something else to try.

Assuming you have at least 2 gigs of onboard memory, install a ramdisk (1 gig in size) and write your timeshift file to that.

If you still get the lag, then we can definately rule out the HDD I/O as being an issue.

See http://www.team-mediaportal.com/manual/TV-Server/UserGuides/Ramdisk for a guide of how to appropriately set the ramdisk up.

"There is no way to Peace -Peace is the Way" (A. J. Muste)

Ashbook

10 posts

Wannabe Geek

#171782 17-Oct-2008 11:56

Hi Quidam. thanks for the help.

My System is:

MB : Gigabyte P35-DS3R
Ram : Crucial Ballistix, 2x2GB, DDR2-800, PC2-6400, CL4, DIMM
HD : Western Digital Caviar RE3 WD2502ABYS
Graphics : Asus 9600GT Slient
TV : Hauppauge WinTV Nova T 500

I setup the Ramdisk and it still jitters, i also tried a Seagate drive and it does the same thing.

could this be a mediaportal problem with timeshifting or the Nova T 500 card?

-Shane

rlevis

355 posts

Ultimate Geek
+1 received by user: 33

#171887 18-Oct-2008 00:24

I use a Hauppauge WinTV HVR-2200, and I don't think it can be a tv card issue because any problems would also appear in recordings. It does sound like a MediaPortal issue to me.

It appears we are not alone based on comments in this MediaPortal forum thread...
http://forum.team-mediaportal.com/general-talk-233/stuttering-livetv-38450/

At least a couple of people mention problems with SD channels and not HD.

I haven't yet checked the tsreader or is it tswriter.log for "continuity" errors. Perhaps you could do that Ashbook.

Note that I have tried the new tsreader.ax file provided near the end of that thread and it seems to have reduced the stutter but not removed it althogether.

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#172200 20-Oct-2008 10:17

rlevis,

ATI Catalyst 8.10 is out, do you have it? Does it make any difference?
I can see you are are using onboard gfx, what is CPU load, do you have HA working?

I installed the nVidia card as most users said this is the way to get a proper picture quality. I would gladly get the nVidia out if I get the same results with the onboard gfx. But then I would have to increase the RAM, right? (I am using 1Gb of it for timeshifting - I just enabled this couple of days ago to see how it goes and for the moment, the CPU load appears to be the same as before and picture quality is the same, didn't decrease or increase - I experience slight stutter when panning at medium speeds on all channels).

Lego

Shop now for Lego sets and other gifts (affiliate link).

rlevis

355 posts

Ultimate Geek
+1 received by user: 33

#172253 20-Oct-2008 14:35

ATI Catalyst is being updated a lot lately. I installed 7.9 about 2 weeks ago. I haven't tried 8.1 yet, but I'm pretty sure that is not my problem. I'm now thinking it could be a MediaPortal issue that I am experiencing with SD channels.

MediaPortal writes the data from the TV Card directly to a timeshift file, and when watching TV live, what it's doing is actually reading from the end of the file. As a software developer myself, my current theory is that the component (tsreader) that reads from the time shift file for displaying on the screen is reading too close to the end of the file, and sometimes the data is not there in time.

This may only occur with SD channels because 4 times less data is being stored than HD, and it may take longer to turn up due to buffering. MediaPortal needs to be modified to read further back from the end of the file, particularly for SD content. I've mentioned this theory on the MediaPortal forums but no one has commented.

I have another possible theory why it only occurs on the TVNZ SD channels and not other SD channels. TVNZ has more data being transferred on their single UHF frequency than the other 2 frequencies. 2 HD and 3 SD channels. Better quality reception will be necessary for the TVNZ signal to receive all the data without any errors.

I found the other day that the aerial plug was partially pulled out of the TV card. I was getting short pauses on all the TVNZ channels but no problems on any other channels.

Now that it's plugged back in properly, I've noticed the stutter on TVNZ 6 & 7 has dimished. I still see it occasionally but not as often. Perhaps it is not a MediaPortal issue. Although the signal quality here is excellent with direct line of sight to the TX.

Regarding your issue with stutter on all channels, if I'm being picky, I do get a little stutter myself but not enough to worry me. I see it on the HD Demo channel more than other channels, and it seems to be there with some programs and not others. So I put this down to the source material at the TV studio.

I have a Zinwell freeview decoder box here as well that I purchased before the HTPC. I plugged this in again the other day and this also shows the same stuttering on the HD demo, so I think it is unavoidable. Perhaps it is the TV.

I am using the onboard 780G chipset/Radeon HD3200 gfx. This supports hardware acceleration and there is very little CPU being used while watching TV. I'm generally very happy with it.

Ross.

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#172274 20-Oct-2008 15:42

Ross,
What codec combination do you use? Did you have to do any "tweaks" in order to get HA working, or it was a straight-forward installation? Would you say the quality you get is comparable with the picture you get from the STB approved decoder?

If I can get rid of the 8600GT, then I can use a MUCH slimmer case. I found PCI risers on eBay for $4, but the PCI-e risers are not so common (and cheap). My mobo has only 2xPCI anyway, and one is "used" by the gfx heatsink. I would like another tv tuner, to add dvb-s and analogue (without replacing the mobo...).
This (http://www.computerlounge.co.nz/components/componentview.asp?partid=5365) is quite nice (slim) but does not take any PCI cards. It would make a nice "client" though...

do you experience the on-board graphics going to "sleep" if the tv is not connected to the htpc? even when all power settings have the "turn off after ... min" option disabled? This situation occurs when watching tv from a diferent source (you switch the TV from the input where the htpc is connected, to another input).

I saw your post regarding the timeshifting issue on MP forum. If you delay tsreader from tswriter, that difference is to be added to the (already quite long) channel switching time, right? Half a sec doesn't sound much at all, but add that to an existing 2 sec delay and you get a 25% increase, which lots of people will notice. But your explanation / solution regarding the stutter, makes sense;

You also said it could be from the tv... what do you mean? How can the tv create the stutter? Due to a low refresh time? Like 8-10ms instead of a fast screen, with maybe 4ms? I was thinking at 8ms, that's already a good LCD screen... most of them are 8ms these days...

rlevis

355 posts

Ultimate Geek
+1 received by user: 33

#172327 20-Oct-2008 17:51

I'm pretty sure I'm getting the same results using the HTPC as the freeview HD box. I must attempt to sell that on Trade Me.

I'm using Cyberlink PowerDVD 8 ultra codecs for both H.263 and MPEG-2.

Unrelated, but I have ffdshow set as postprocessor for upsampling DVD's and movies. This makes a lot of difference to the quality of DVD's, which almost look HD. This does require quite a bit of CPU.

I don't think I've noticed the gfx going to sleep. I usually switch the PC to "Away Mode" overnight as I think that saves some power and heat. This turns off the audio and video but keeps everything else functioning as usual. The bios of the motherboard needs to support "Away Mode" for this to work, and requires Windows Vista. I just have to press a remote button to bring it back up.

If MediaPortal is the problem some of us are experiencing, then an extra 100 milliseconds should not be noticeable.

I'm only guessing about the TV. My 32" Sony Bravia D series is 8ms. I've heard some say that their 100 hertz plasma TV doesn't show any panning jitter at all watching MySkyHD. Perhaps it is an LCD issue, or a 50 hertz issue. I haven't seen enough other systems to compare with unfortunately.

Considering the Zinwell freeview box looks the same on my TV with the same minor jitter issue, then I guessed it must be the TV or simply as good as you get with digital.

Does anyone know if enabling the "LCD Overdrive" setting in the ATI Catalyst Control Center is of any use. I read that it is designed to emulate a faster response time on LCD panels, but perhaps on panels that are slower than 8ms. I'm not sure.

Ross.

Ashbook

10 posts

Wannabe Geek

#173999 28-Oct-2008 09:46

Hey rlevis, so you sure you've have had no jitter since you pluged in your aerial properly? Wouldnt that have effected recorded tv as well?

Im still thinking its a mediaportal + timeshift problem as i've noticed something else. If mediaportal starts on tv6 (e.g i turn to tv6, then restart mediaportal) there is no jitter, its only after a channel change that i get the jitter.

i've still got jitter hell on 6 and 7. i tried the tsreader you mentioned from the other post but it didnt effect anything.

This is seriously annoying.

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