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

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

Post#41 » Sat Jul 06, 2013 3:42 pm

foxwood wrote:
ziggyball wrote:The only thing I can do at the moment is to watch back recordings in a different media player...
You must be mistaken - according to Richard, any fix implemented in software is actually worse than just leaving things as they are.

That is correct. Leaving WMC as-is, there are only two groups of people that are adversely affected by fluctuating progressive_frame flags:

  1. People that use a GPU that is not sufficiently powerful enough to handle the fluctuations without dropping frames;
  2. People that attempt to watch content encoded with incorrect progressive_frame flags.
Attempting to create a software solution for group 1 may mitigate the stuttering, but it introduces other problems that affect not only the people in group 1, but the people not in group 1 as well. The same is also true for group 2. Additionally, some ideas for a software solution designed to "fix" fluctuating progressive_frame flags will adversely affect content that doesn't have fluctuating progressive_frame flags in the first place.

So to put it simply, a software solution designed to help a small subset of WMC users will actually end up negatively affecting nearly every WMC user. That is what makes a software solution worse than leaving WMC as-is. At least by leaving WMC as-is, the small subset of users that experience stuttering due to fluctuating progressive_frame flags have a solution that doesn't involve negatively impacting everyone else.
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Post#42 » Sat Jul 06, 2013 4:02 pm

richard1980 wrote:
foxwood wrote:
ziggyball wrote:The only thing I can do at the moment is to watch back recordings in a different media player...
You must be mistaken - according to Richard, any fix implemented in software is actually worse than just leaving things as they are.

That is correct. Leaving WMC as-is, there are only two groups of people that are adversely affected by fluctuating progressive_frame flags:

  1. People that use a GPU that is not sufficiently powerful enough to handle the fluctuations without dropping frames;
  2. People that attempt to watch content encoded with incorrect progressive_frame flags.
Attempting to create a software solution for group 1 may mitigate the stuttering, but it introduces other problems that affect not only the people in group 1, but the people not in group 1 as well. The same is also true for group 2. Additionally, some ideas for a software solution designed to "fix" fluctuating progressive_frame flags will adversely affect content that doesn't have fluctuating progressive_frame flags in the first place.

So to put it simply, a software solution designed to help a small subset of WMC users will actually end up negatively affecting nearly every WMC user. That is what makes a software solution worse than leaving WMC as-is. At least by leaving WMC as-is, the small subset of users that experience stuttering due to fluctuating progressive_frame flags have a solution that doesn't involve negatively impacting everyone else.


I'm running an APU, an AMD A8 which is more than powerful enough, but I saw the judder. That excludes me from group one then. Are you saying that the Beeb are encoding with incorrect progressive frame flags?
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Post#43 » Sat Jul 06, 2013 4:30 pm

No. My response was specific to stutter caused by fluctuating progressive_frame flags. I don't think the stutter discussed in this thread is caused only by fluctuating progressive_frame flags, as US content with fluctuating flags plays smoothly on my GPU but UK content doesn't. However, fluctuating progressive_frame flags combined with the wrong GPU will certainly result in stuttering.

That said, you may want to reconsider your statement that your GPU is more than powerful enough. As it pertains to this discussion, "powerful enough" means powerful enough to correctly process 3 frames of MPEG video with alternating progressive_frame flags without dropping the 2nd frame. I don't know if your GPU is powerful enough or not, but don't just assume that because it's powerful enough for other tasks that it's powerful enough for this task. I remember someone not long ago that had a very powerful (overall) $1000 GPU that simply was not powerful enough to process the fluctuating progressive_frame flags without stuttering, even though much weaker (overall) GPUs are able to process the fluctuating progressive_frame flags without stuttering.
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Post#44 » Sat Jul 06, 2013 4:35 pm

richard1980 wrote:No. My response was specific to stutter caused by fluctuating progressive_frame flags. I don't think the stutter discussed in this thread is caused only by fluctuating progressive_frame flags, as US content with fluctuating flags plays smoothly on my GPU but UK content doesn't. However, fluctuating progressive_frame flags combined with the wrong GPU will certainly result in stuttering.

That said, you may want to reconsider your statement that your GPU is more than powerful enough. As it pertains to this discussion, "powerful enough" means powerful enough to correctly process 3 frames of MPEG video with alternating progressive_frame flags without dropping the 2nd frame. I don't know if your GPU is powerful enough or not, but don't just assume that because it's powerful enough for other tasks that it's powerful enough for this task. I remember someone not long ago that had a very powerful (overall) $1000 GPU that simply was not powerful enough to process the fluctuating progressive_frame flags without stuttering, even though much weaker (overall) GPUs are able to process the fluctuating progressive_frame flags without stuttering.


So how come that I don't have this issue using MediaPortal and LAV filters?

Why don't users with set top boxes have this issue? Surely their gpu/CPU isn't any more powerful than my amd?
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Post#45 » Sat Jul 06, 2013 6:01 pm

foxwood wrote:
ziggyball wrote:The only thing I can do at the moment is to watch back recordings in a different media player...
You must be mistaken - according to Richard, any fix implemented in software is actually worse than just leaving things as they are.


Well, if I play the recorded WTV file in PowerDVD then it seems to play back without the jitters/flashes...
Obviously not a fix but a way to watch an HD program, after it's finished recording :(
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Post#46 » Sat Jul 06, 2013 6:01 pm

wyerd wrote:So how come that I don't have this issue using MediaPortal and LAV filters?

There are multiple possible reasons:

  1. The stuttering you observe in WMC is not due to fluctuating progressive_frame flags, but is instead due to some other problem.
  2. Processing is done by the CPU, not the GPU.
  3. The progressive_frame flags are being ignored.

wyerd wrote:Why don't users with set top boxes have this issue? Surely their gpu/CPU isn't any more powerful than my amd?

The graphics processors used in typical consumer electronic devices like set-top-boxes, TVs, and AVRs are significantly more powerful with regard to video processing than anything you'll find available for your computer. Computer GPUs may be good for gaming, but they are a very poor choice for video processing. Just think, the typical PC GPU struggles just to decode 60 frames per second, and in most cases fails to maintain 60 Hz capability once you enable any post-processing, whereas the electronics stores are full of TVs that easily decode and fully post-process frames at much higher rates. Consider a 120 Hz TV as an example. It reaches 120 Hz by displaying each frame of 60 Hz video 2 times, which means that it has to fully decode and post-process each frame in less than 1/120th of a second....for an effective frame processing rate of 120 frames per second. But 120Hz is just the tip of the iceberg. Consider TVs that have 240 Hz, 480 Hz, 600 Hz, and even 1200 Hz refresh rates.
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Post#47 » Mon Jul 15, 2013 4:49 pm

richard1980 wrote:I used to have a program that would allow me to step through frame by frame and it would show me the headers. I really liked that program because it had a video screen and I could view the header data along with the recomposed picture simultaneously...which allowed me to identify when the progressive_frame flag was set incorrectly.

I found the program...it's called DGIndex. You can get it from here.
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Post#48 » Tue Jul 16, 2013 4:52 am

Ok its definately changing from 50fps to 25fps at times. I'm not sure stutter is at the same time as fps change though....
Wimbledon Red Button, British GP F1 Red Button events are gone yet judder remains.... so i guess encoding changeover wasnt temporary :-(

The only programmes I watch on BBC is Match of the Day and F1. I've really enjoyed them in HD but I guess it's down to watching recorded BBC in Plex from now on....
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Post#49 » Tue Jul 16, 2013 9:22 am

I just noticed BBC have announced the launch of 5 new HD channels --
BBC Three HD, BBC Four HD, BBC News HD, CBBC HD and CBeebies HD
(Source http://www.bbc.co.uk/mediacentre/latest ... nnels.html)

Could be a whole new world of juddering for 7MC users.
Last edited by Pixelz on Tue Jul 16, 2013 9:50 am, edited 1 time in total.
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Post#50 » Tue Jul 16, 2013 9:49 am

@AndyBMK
Having re-read this thread, I noticed you saw a reduction in juddering after downgrading from a Radeon HD6570 to an HD6450.
I'm desperate enough to swap out my 6570 even though the GPU clock speed would be reduced from 650 to 625 MHz.

I was looking at a fanless Sapphire Radeon HD6450 with 1Gb DDR3 and 625MHz clock (Not the Flex version).
Does this match your GPU spec, and can you let me know what version of the Catalyst Drivers you're using (as I've seen lip-sync issues with some recent versions).
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Post#51 » Tue Jul 16, 2013 4:52 pm

HAHA, I was excited there for a second (we record alot of CBeebies in our house) but if judder is not going away, I will keep SD versions in our guide.

Since MCE7 is pretty much dead, I hope MediaPortal improves in the next couple of years to be viable option for (family) friendly DVR software.

Pixelz wrote:I just noticed BBC have announced the launch of 5 new HD channels --
BBC Three HD, BBC Four HD, BBC News HD, CBBC HD and CBeebies HD
(Source http://www.bbc.co.uk/mediacentre/latest ... nnels.html)

Could be a whole new world of juddering for 7MC users.
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Post#52 » Sun Jul 21, 2013 2:32 pm

Pixelz wrote:@AndyBMK
Having re-read this thread, I noticed you saw a reduction in juddering after downgrading from a Radeon HD6570 to an HD6450.
I'm desperate enough to swap out my 6570 even though the GPU clock speed would be reduced from 650 to 625 MHz.

I was looking at a fanless Sapphire Radeon HD6450 with 1Gb DDR3 and 625MHz clock (Not the Flex version).
Does this match your GPU spec, and can you let me know what version of the Catalyst Drivers you're using (as I've seen lip-sync issues with some recent versions).



Hi Pixelz,

Apologies for the delay in responding. It sounds as if you're looking at the equivalent model, I'm using an Asus EAH6450 SILENT/DI/1GD3(LP) (specs: http://www.asus.com/Graphics_Cards/EAH6450_SILENTDI1GD3LP/#specifications). I'm currently using driver version 12.104.0.0 and Catalyst 13.4 but I have all post-processing disabled (and having the "Enable Smooth Video Playback" option ticked).

I use AC3Filter (version 2.5b) for audio processing and use that to adjust lip-sync and other audio properties.

As I wrote earlier, I've seen a massive improvement in what was previously an unwatchable situation, however I still notice an occasional stutter but whether this is part of the same issue or just something else, I can't say. The broadcasts of the recent British GP and current Open @ Muirfield (particularly fast-action shots) have been a world-apart from the continual stuttering seen prior to my GPU change (previously every few seconds, sometimes even more frequently). I'd made a recording of The Sunday Politics from a few weeks ago when I had my original GPU because I noticed bad stuttering whilst the camera panned and then focused on one of the interviewees however this stuttering is now not noticeable when I play the same clip back through the HD6450.

Good luck with the "downgrade"!

Andy
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Post#53 » Mon Jul 22, 2013 2:38 pm

Thanks for the information. I'll post the results when I get a chance to try this.
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Post#54 » Wed Jul 24, 2013 9:28 am

Well, I've finally given up on MCE and have switched to Mediaportal. It was a reasonably easy transition, and while some things are a lot better (not only the lack of stuttering) others are arcane to say the least, such as the way it handles resume/standby which requires a plugin to work correctly. Everything is configurable, which is good, but also can be confusing .. there's almost too much choice.
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Post#55 » Sat Jul 27, 2013 5:58 pm

Thanks for the information. I'll post the results when I get a chance to try this.


Have to agree with you that the lower spec HD6450 GPU is way better at handling these frame-rate changes. And it only cost me £29.

I watched BBC1HD today with the new card, existing drivers, and unchanged settings for zero post-processing. Both the athletics and the F1 qualifying were fine, where I would have expected juddering with the HD6570.

As a further test, I replayed an old recording of BBC News broadcast overnight on BBC1HD. This included the horizontal news ticker that made the juddering very obvious. If I look carefully, I can still see a trace of a judder -- but I'd not say it's something you'd notice unless you were warned in advance.

So overall I'm much happier, and the 6570 is headed for eBay.
Thanks for the tip -- although it's a still a mystery to me why this makes such a difference!
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Post#56 » Sat Jul 27, 2013 7:31 pm

The theory that a card isn't powerfull enough to handle the switching in the frame rates doesn't look promising. I'm using an HD7950 @1Ghz. It should be plenty enough!
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Post#57 » Sat Jul 27, 2013 9:46 pm

And Einstein should have been able to tie his own shoes...

From post #43:

richard1980 wrote:As it pertains to this discussion, "powerful enough" means powerful enough to correctly process 3 frames of MPEG video with alternating progressive_frame flags without dropping the 2nd frame. I don't know if your GPU is powerful enough or not, but don't just assume that because it's powerful enough for other tasks that it's powerful enough for this task. I remember someone not long ago that had a very powerful (overall) $1000 GPU that simply was not powerful enough to process the fluctuating progressive_frame flags without stuttering, even though much weaker (overall) GPUs are able to process the fluctuating progressive_frame flags without stuttering.
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Post#58 » Sun Jul 28, 2013 9:25 am

Richard, I'm sure you're probably correct. It justs seems odd that a (marketed as) high end GPU isn't able to do that. I was just contributing to this thread with my findings!

It seems odd though, that when I watch the stream through VLC w/ DVBLink, it doesn't flicker.

So to me, it doesn't look like a GPU issu. The horsepower is enough, the signal is enough. Therefor, the problem must lie in software. At least, that's IMHO.
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Post#59 » Sun Jul 28, 2013 2:03 pm

I was actually involved in a similar discussion about a week ago (although instead of VLC we were talking about LAV), and I think a lot of what was discussed applies here as well. To summarize the other discussion, the OP wanted to change the decoder that WMC uses because he observed better deinterlacing performance with LAV vs the Microsoft DTV decoder. He was convinced that Microsoft's decoder was at fault. It was suggested that he try a different GPU...which led to him arguing that there was no problem with his GPU because it worked just fine with LAV. Unfortunately, he was wrong...the reason he saw a difference was because when he was using Microsoft's decoder, deinterlacing was being offloaded to the GPU via DXVA, whereas when he switched to LAV, deinterlacing was being offloaded to the GPU via CUDA. He was comparing apples to oranges, and wasn't able to make an apples-to-apples comparison because LAV is unable to offload deinterlacing to the GPU via DXVA (even when LAV is running in DXVA mode). Ultimately, copy protection forced him to leave WMC set to use the Microsoft decoder, so he upgraded his GT 610 to a GT 640. After doing so, here is what he posted:

tzr916 wrote:After searching for HQV results, I went with a GT640 fanless. WMC with MS decoder does look much better. Almost 95% of the video defects I was seeing with the GT610 are gone. It's enough to be satisfied (for now). Just very disappointing that WMC decoder is DXVA / locked down and requires so much GPU just to get a decent picture.


You can read the full thread here: www.thegreenbutton.tv/forums/viewtopic.php?f=5&t=5563

I've been actively involved in several discussions about the progressive_frame flag for a few years now, and every time someone tries to compare WMC performance to something else (e.g., other software, set-top-boxes, etc.), it always ends up being an apples-to-oranges comparison, and I suspect the same is true in your case. What you are seeing in VLC is likely due to VLC not offloading deinterlacing to the GPU via DXVA. It's likely either offloading deinterlacing to the GPU via some other API, or it's not offloading deinterlacing to the GPU at all. Even if VLC is offloading deinterlacing to the GPU via DXVA, it may not be honoring the progressive_frame flags.

As far as the GPU power goes, the overall power of the GPU is irrelevant...what matters is how powerful the GPU is at performing this specific task. Unfortunately, most GPUs are better suited for things like gaming instead of playing video that contains fluctuating progressive_frame flags.
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Post#60 » Sun Aug 11, 2013 1:09 pm

Currently I have an NVidia GPU, originally had an ATI but there were issues a few years back with ATI and BBC HD :(

So from this I deduce that swapping to an HD6450 will fix these juddering issues, presumably this card will have sufficient power to use Total Media Theatre for my Blu-Ray playback?

I nearly reverted to Media Portal which I used a few years back but never got on with and my family hated that.
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