Judder/Stutter on BBC1 & 2 HD via DVB-S2

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Judder/Stutter on BBC1 & 2 HD via DVB-S2

Post#1 » Fri Jun 21, 2013 11:17 am

I'm running 7MC on a FM2 A8 system and have two dual tuners, a Blackgold BGT3620 and a TBS 6981. I do get juddering with the DVB-T2 tuner on BBC HD tuners due to the mixed 1080i/p they use, but this isn't used on S2. It started happening last Thursday which I thought was due to the latest windows updates, so I rolled back, but I still get the judder. I've tried different AMD display drivers, still get the judder.

Is anyone else getting this? Any pointers to get smooth playback again?

Thanks.
wyerd
 
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Post#2 » Fri Jun 21, 2013 12:26 pm

Is your refresh rate still set ok after updating the drivers?
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holidayboy
 
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Post#3 » Fri Jun 21, 2013 12:33 pm

holidayboy wrote:Is your refresh rate still set ok after updating the drivers?


All ok at 50Hz.
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Post#4 » Fri Jun 21, 2013 4:18 pm

Is there a dynamic contrast setting in the AMD stuff you can try disabling? I think I saw a post somewhere saying to untick inverse telecine deinterlace maybe? All guesswork as I have nvidia and Intel cards.
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Post#5 » Mon Jun 24, 2013 11:45 am

i started noticing this recently, still trying to work out exactly what it is. i noticed some new intel drivers came out so i've installed these. i also noted that my refresh rate had slipped back to 59i (it does this occasionally) so i've changed that back.

i'll let you know if it improves
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Post#6 » Wed Jun 26, 2013 2:24 pm

I'm guessing the DVB-S2 stutter is due to encoder changes associated with the enhanced Red-Button HD service, which was launched recently to cover Wimbledon/Glastonbury/British F1/etc. Really hope it's only temporary, otherwise (as far as I can see) there's no stutter-free HD broadcast platform available for UK Media Centre users.
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Post#7 » Sat Jun 29, 2013 6:49 am

I'm also experiencing stutter on BBC1 HD via DVB-S2. It has started happening in last 1 week, that i noticed.
I havent installed anything in past 3 months, automatic updates are disabled.
By the way, I'm using nVidia graphics card and did not upgrade drives in 3 months HTPC has been setup.

I sure hope it's not because of the new encoding options as getting Microsoft to fix it will be nigh impossible.
Last edited by wally007 on Sat Jun 29, 2013 8:07 pm, edited 1 time in total.
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Post#8 » Sat Jun 29, 2013 1:42 pm

Same here, only started noticing in recently, during the Confederation's Cup. It drives me NUTS!
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Post#9 » Sun Jun 30, 2013 9:53 pm

I have the same problem here. Thought I had some malware installed robbing my processor time until I noticed that it only happened on the bbc hd channels. It always seems to be the bbc that mess up the encoding - never had a problem with sky.
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Post#10 » Mon Jul 01, 2013 12:07 pm

Has anyone fixed the issue ? I almost threw out the TV during Formula 1 race this weekend.
Things like this can drive me up the wall :-)

Btw, I'm using Freesat Dish -> USB2 ElGato DVB-S2 -> DVBlink TV source -> Windows 7 Home Premium -> Quadcore i5, Nvidia 650ti -> Panasonic 50" PLasma via HDMI -> DVI.
CPU utilisation is below 10 % and GPU is about 30-40%

Sometimes it goes 10 20 seconds without stutter and then it gets so choppy ..... It's very easy to see with Formula1 and/or Football.
It started stuttering few weeks ago. Channel4 HD is fine.
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Post#11 » Mon Jul 01, 2013 7:12 pm

YIPPEE!!! Well, not yippee, really, but I'm glad someone else has spotted this and I'm not imagining things!!

It's started happening all by itself in the last weeks, and only affects the BBC HD channels. ITV HD and Channel 4 HD, alonmg with all the German HD channels on Astra 19.2 are perfect.

It's most noticeable on long panoramic camera sweeps, so as one poster said, watching the F1 on Sunday was an awful experience. I turned over to the SD equivalent to retain my sanity. It's only very, very minor most of the time, but just enough to be annoying.

I even went to the extent of a complete re-installation of Windows and MCE just to rule everything else out, but it's still there.

My money is on someone in the BBC 'tweaking' the encoder but I reckon the chances of getting them to admit it is close to zero.
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Post#12 » Mon Jul 01, 2013 7:51 pm

Hi,

we're having the same issue - its very annoying even on a program such as The Graham Norton show... may have to disable the 2 BBC HD channels while this continues!
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Post#13 » Tue Jul 02, 2013 8:57 am

A solution at last ... install the latest LAV filters and use Win7DSFilterTweaker to disable the MS DTV codec (and the audio ones too if you like). Works for both live TV and recorded TV.

A while ago I tried using ffdshow to achieve the same effect but it didn't work, but for some reason the LAV decoders work seamlessly.
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Post#14 » Tue Jul 02, 2013 9:15 am

As far as i remember, with LAV filters you would loose thumbnails on recordings and can not fast forward properly ?

Can you please test fast forward, skip/jump 30secs, 5 mins and let us know if it works fine ? Do you also get thumbnails on recrodings that were made once you started using LAV filter ?

Thanks for letting us know !

AlunS wrote:A solution at last ... install the latest LAV filters and use Win7DSFilterTweaker to disable the MS DTV codec (and the audio ones too if you like). Works for both live TV and recorded TV.

A while ago I tried using ffdshow to achieve the same effect but it didn't work, but for some reason the LAV decoders work seamlessly.
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Post#15 » Tue Jul 02, 2013 9:30 am

Drat, you're right ... no thumbnails which isn't really a biggy, but fast forward breaks it requiring a restart of MCE.

Skip forward and jump back (I have mine set for 4mins forward (avge. ITV/CH4 ad break), 1 min back) works fine though.
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Post#16 » Wed Jul 03, 2013 9:00 am

Hi everyone

I've been a regular viewer of this forum and it's given me solutions for several issues I've had with my set up over the past couple of years. I've joined so that I can return the favour by relating my experience of this frame judder issue.

I first noticed this problem around the time of the BBC televising tennis from Queens (I'm not a great tennis fan but I found the judder was particularly noticeable during these broadcasts), however the judder could be seen continually during any programme, even upscaled ones, on BBC HD channels. It didn't occur on any other UK high-def free-to-air channel (either DVB-S2 or DVB-S). A search of the web found only the older Freeview BBC DVB-T2 25/50 fps switching issue which I assume is still unresolved and this seemed to be associated with the even older but virtually identical 29/60 fps "bug" issue being experienced in the US.

Have a look at this for an excellent explanation and suggested workaround: http://experts.windows.com/w/experts_wiki/71.aspx.

Certainly if you debug (by 4-1-1-Info) you will see the frame rate momentarily flicker from the usual 50 continually throughout the broadcast and it usually corresponds with the judder. It's such a brief drop from 50 fps, it's difficult to actually see what the momentary fps is (I think I saw 25 a few times and a member of my family thinks she saw 49 "point something", so it might be all over the place). Do the same debug for a non-BBC DVB-S2 free-to-air channel (or any DVB-S SD or HD channel) and the fps stays a rock solid 50 (I referred to http://www.lyngsat.com/Eutelsat-28A-and-Astra-1N-2A-2F.html to show which high def channels are using DVB-S2 since some HD channels such Channel 4 HD and some ITV HD versions are using DVB-S).

You will see from the wiki above that the workaround has been to try one of a small number of GPUs immune to the issue. I was using a Radeon HD 6570 on my Media Center but was able to swap it with an HD 6450 being used on a different PC in my house. Since using the HD 6450, there seems to have been a 99% improvement. I'm reluctant to say 100% as I occasionally notice the odd extremely slight stutter - absolutely nothing as bad as before and nowhere near as frequent - but that might be simply because I'm casting an excessively-critical eye at the screen since the problem began (no one else in my family seems to think there is a problem since the change of GPU).

I'm sure a change of GPU isn't going to be welcomed by many users and I wasn't too happy downgrading from my HD 6570 however I found the perpetual juddering was making BBC HD channels unwatchable and I'd already invested too much time and money in my set up to have to go back to using set top boxes. Clearly the source of the problem is the BBC and I suspect an unadvertised change on their part has caused this however, assuming the similar issue with DVB-T2 remains unfixed, I guess the reality has to be the workaround as our only option.
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Post#17 » Wed Jul 03, 2013 10:06 am

Thanks for the very detailed explanation. Unfortunately my setup is an AMD Zacate based one, and the only PCIe slot is taken up with a DVB-S/S2 tuner so no opportunity to replace with a better/faster GPU.

What would be your interpretation of the improvement seen by me when using LAV decoders instead of the MS decoders?
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Post#18 » Wed Jul 03, 2013 11:04 am

My first guess (and it is a pure guess) is that the Lav codec might be outputting at a constant frame rate maybe, rather than switching between 25/50?
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Post#19 » Wed Jul 03, 2013 11:05 am

I'm sorry Alun and Holidayboy, the honest answer is that I simply don't know. The issue is certainly quite complex as I understand the problem can still exist using some of those "immune" GPUs unless post-processing has been disabled. Ideally the issue should, of course, be corrected at its source however I suspect the BBC is very unlikely to resolve it since it has been one that has affected DVB-T2 users for longer (and I'm assuming it's still ongoing with Media Center users of that platform unless they've tried workarounds). I don't know if the issue also affects MediaPortal, XBMC, etc on Windows and / or Linux or just us. Either way I think since HTPC users form a relatively-small number of viewers I just can't see the problem being resolved at the pre-broadcast stage (I live in hope I'm wrong though!).
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Post#20 » Wed Jul 03, 2013 11:13 am

Another guess: Maybe lav is using different hardware decoding settings, there are settings in lav for dxva/cuda I think.
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