Frame dropping - Slow GPU?

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Streamerke Offline
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Post: #1
Hi all,

I came to the conclusion today that I probably need to upgraden my GPU anyway today. I just want to confirm this with you more experienced XBMC users.

OK, here goes:

When I play full HD movies, I see a short stutter every now and then, every few seconds. It depends a little bit of various setings that I played with however it is always there. When I put debugging on then I see a framerate around 24FPS. The strange thing is: it is hardly ever exactly 24FPS while bluray sources are 24FPS, or 23.976FPS for that matter.
The reported framerate goes up and down and every time I see a little stutter I noticed that the reported framerate drops below 22FPS.

My CPU load never even reaches 20% so I guess the CPU has more than enough power to handle the tasks. So I guess the problem is caused by my GPU. By the way, the problem is there with both DXVA2 on and off. Can anyone confirm the problem is GPU related? See the hardware info below.

This is my hardware:

CPU: Intel Core 2 Quad Q9450 @ 2.66Ghz
GPU: Nvidea Geforce 9600 GS with latest drivers v.296.10 WHQL
(This post was last modified: 2012-05-01 23:24 by Streamerke.)
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PatK Offline
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Post: #2
Have you had a look at the figures while playing a video? (keyboard 'O' command) if you're close to threshold on either the GPU or CPU.. then you have your answer. But if everything looks nominal... then look for some sort bottleneck around file delivery, or software conflicts. Make sure you have an updated graphic driver and you don't have post processing anywhere.

Post a debug with either killasample or some intensive video going on.
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tman12 Offline
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Post: #3
I will say one thing to you, think long and hard before spending money on more powerful hardware. I have a very powerful A8-3870k and I have problems/issues - granted all of my files are high bitrate blurays so I guess it depends on what you're playing. I'm not saying I'm unhappy with XBMC performance, I'm just saying it wasn't worth the money I put into it for the results.

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Streamerke Offline
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Post: #4
Cheers PatK, that 'O' command was a good tip!

By using the O command I could actually confirm the frame dropping, even though no more than say 150 frames in a few minutes were dropped. Still it was very noticeable.

The problem shows up in constant quality encoded H264 movies. In very active scenes the bitrate shoots up to 30Mbps. It is here that frames get dropped.

I am playing with DXVA2 off as for some reason this setting creates problems for my home movies. I thought that I tested with DXVA2 on. Well, now I did the test again with DXVA2 on and ... no frame dropping whatsoever. I am totally confused as I thought I did notice this last week with DXVA2 on.

Perhaps need to look for that killasample... I will come back later when I had some more time to test.
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bluray Offline
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Post: #5
(2012-05-02 22:27)Streamerke Wrote:  I am playing with DXVA2 off as for some reason this setting creates problems for my home movies. I thought that I tested with DXVA2 on. Well, now I did the test again with DXVA2 on and ... no frame dropping whatsoever. I am totally confused as I thought I did notice this last week with DXVA2 on.
It tend to work better with DXVA2 enabled, and use DXVA as Render Method and disable everything else in XBMC settings/video/playback. You can try to disable "Use a window fullscreen rather than true fullscreen" in XBMC settings/system/video output too.....

>Alienware X51- do it all HTPC
>Simplify XBMC configurations
>HOW-TO Bitstreaming using XBMC
I refused to watch movie without bitstreaming HD audio!
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jhsrennie Offline
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Post: #6
1080p at 30Mbps is marginal without hardware acceleration.
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Streamerke Offline
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Post: #7
Dear all,

Yesterday I played a complete film with DXVA2 enabled. In my short test earlier this week I did not notice any problems. Now I can confirm I still have problems with DXVA2.

On a total movie there were some 120 frames dropped which is marginal however very noticeable.

I am still puzzled on what the cause might be:
- From time to time I notice a hickup and when I check the O command no frames were dropped, sometimes there were. Is a "near miss" possible.
- Why is XBMC so "inefficient" with system resources. Inside XBMC I cannot seem to play a full HD movie without problems while in other software I can play 28Mbps x264 1080p50 without any problems. That does not add up...!

I think there might be another issue but I do not know where to look...
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MONSTA Offline
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Post: #8
(2012-05-05 19:07)Streamerke Wrote:  x264 1080p50
Try nightly builds,which until April 30 ( later released something new and non-working Big Grin).They changed the decoder and no more problems with large fps video .If it's not about interlace,that still bad.
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zodduska Offline
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Post: #9
Try changing your Nvidia control panel power management setting to "prefer maximum performance" the default setting is adaptive.

I have a GTX 480 and was having similar issues, the problem was that the card downclocks to 50mhz to save power, changing this setting fixed my intermittent choppy framerate issues by preventing the downclocking. By the way I'm not using DXVA.
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Streamerke Offline
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Post: #10
Because of other reasons I have put in a cheap but new GPU, a Geforce 520 GT. First tests show that I have no more frame dropping and from what I could see everything looks fluent. I need to do some more testing when I have the time but this looks promising!
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Streamerke Offline
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Post: #11
Dear all,

This issue has been SOLVED. In fact there were two causes of the problem of judder/stutter in full HD movies.

Problem

I noticed some judder/stutter in full HD movies. The problem was quite irregular, movies could run smooth for seconds on end and then suddenly there was a short stutter as if one or more frames were skipped from playback. This was visible when the camera was panning but also during action scenes.

I noticed with the O command that in full HD movies indeed some frames were skipped, about 100 in a complete movie, so not a lot. The number of frames lost could not explain what I saw on the screen. I had a feeling there was another issue. In fact I noticed that also SD material did not play as fluently as on a normal DVD player.

Solution

It seems my Geforce 9600GS was not enough to display high bitrate H264 encoded material without frame dropping. I have put in a Geforce 520 GT. Afterwards the frame dropping was gone.

I still noticed some additional judder/stutter though. It was frustrating the hell out of me but I could not put my finger on it. My PC though 4 years old is a regular power plant so power could not be the problem.

I found out that the cause of the remaining problem was this:

I use Windows in a lower resolution as my XBMC. The reason is simple: even though my TV screen is large (46") full HD resolution is too high to be working in Windows. I use Windows to play browser games and do some occasional video editing. When in XBMC I want full HD of course.

I noticed that XBMC does not play video well when resolution set in XBMC is higher than the settings in Windows. When I first switch to full HD before starting XBMC the problem is gone!

Finally I can start watching movies and enjoy the content instead of worrying about the playback!
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