View Full Version : Decoding performance vs Windows
This has been reported in the Live forum as well, as the base for Live is Hardy too but I thought it could have been interesting to discuss it in the Linux forum, as that is the actual platform I'm having the problem with.
My hardware:
Motherboard Gigabyte GA965P-DS3 (rev 3.3)
CPU E2160 clocked at 3.0 GHz
RAM 2GB
Videocard Nvidia 8800GT 512MB (w/ latest drivers from Nvidia website both for XP and Ubuntu environments, 178.24 on Windows, 177.80 on Ubuntu)
Onboard Sound
Onboard NIC
Display 50" 1366x768 Panasonic plasma, driven at native res through VGA
With the above, the killer sample playback loses lots of frames under Ubuntu Hardy (64 bit) and is perfect under Windows XP SP2. Furthermore, not only the Killer sample is losing frames, lots of Planet Earth 1080p content has problems.
As I'm investigating judder problems (http://xbmc.org/forum/showthread.php?t=38530) under Windows, my Ubuntu install is really XBMC dedicated, I have not added anything else (there is XBMC, Nvidia drivers, LIRC, ALSA... stop).
Edit: I'm running under 64 bit Ubuntu, I have installed XBMC through the standard repository and it seems to be working normally. Should I have done things differently under the 64 bit OS?
althekiller
2008-10-20, 22:12
No one on the team currently has 64bit available to them for testing. 32bit hardy would be a better test.
No one on the team currently has 64bit available to them for testing. 32bit hardy would be a better test.:laugh: I was afraid of an answer like this.
Fair enough, I should have checked the Wiki *before* installing. :;):
I'll try to reinstall ASAP and come back with more.
I run hardware much like what you've described - no dropped frames running Killa' on my setup. I had some shuddering that I tracked down to my TV (!) but once resolved seems to now be smooth as glass. 3GHZ is fast enough, my CPU is now running a bit faster than that though. Planet Earth material, of which Killa' is sourced, is plain demanding all around. Prior to bumping my CPU up Killa' and other Planet Earth stuff really allowed me to see issues, other shows less so but I did occasionally see dropped frames. I encode my own BD rips and other HD rips and I know my bitrates are sky high, however your hardware looks as good as mine and I no longer see issues since bumping my CPU. A 32bit Ubuntu install might be all you need honestly. Have you tried the LiveCD? that would be an EASY way to check performance without having to reinstall all over again...
Tried the Live CD. No frames were lost.
Re-installed Ubuntu 32bit with the built-in (well, the suggested package anyway) Nvidia drivers and now I lose no frames.
Still, at 48Hz, 24fps (23.976) content suffers from some juddering (no frames lost, I stress) which I can track back to the absence of a Reclock-like mechanism.
It's really a shame, the interface is so far ahead of everything else :sniffle:
@ ashlar, tone it down a bit.
Donating don't mean you can say whatever you want whenever you want
We're of course gonna keep improving XBMC.
@ ashlar, tone it down a bit.
Donating don't mean you can say whatever you want whenever you want
We're of course gonna keep improving XBMC.pike, I honestly don't know how to answer this. What exactly have I said to provoke this reaction?
What has donating to do with this thread?
we are still in a FeatureFreeze...
you make it sound like we should add a Reclock feature NOW, or yesterday
it's an important feature INDEED, but we can't do it before Atlantis.
Then I noticed you also were warned before (not by me)...
Never thought of "demanding" it before the Atlantis release. Reading that you consider it an important feature is great, though, as for a lot of people stuck at 60Hz I understand is not relevant.
I used the expression "shame" because of the overall awesomeness of everything else in XBMC. And I donated because of appreciation, not because I thought of it as a ticket to free thread-crapping.
On the other hand, I'm not a programmer, I love what you create... what else could I do? It's something that I planned on doing for a long time and, ironically, it's come now that I am not using XBMC.
To be honest your words on the donation were pretty discouraging.
As for the warning, I've never been warned before, not that I know of. What are you referring to?
Pvt_Ryan
2008-10-22, 12:27
No one on the team currently has 64bit available to them for testing. 32bit hardy would be a better test.
If you need something tested let me know. I have a few x64 machines, and have no issues rebuilding them if needed.
This is interesting. In what way is XBMC bad when playing 24fps material?
I building a machine for this exact purpose (mostly,anyway) and would like to know the details.
This is interesting. In what way is XBMC bad when playing 24fps material?
I building a machine for this exact purpose (mostly,anyway) and would like to know the details.This is taken from the readme of Reclock (a Windows sound renderer):When you connect your PAL DVD player to your TV, things are really simple. Your player read the movie from the disc at 25 fps, and sends the signal to the TV at 25 fps.
Now imagine that your player is a little too fast and send the movie to the TV at 25.01 fps. What will happen? Jerkiness? No … In fact your TV is smart, and will stay synchronised with your player as long at the player plays near 25 fps. To be more precise no player in the world plays the movie exactly at 25 fps because clocks are never accurate. So every player play the movie “near” 25 fps, but this is no problem for your TV since it is locked to the video signal it receive.
Now when you play a DIVX on your PC and watch it on your PC what happens? First of all, if the refresh rate of your monitor is not a multiple of the frame rate of your DIVX, jerkiness will happen for sure. Do you remember that DIVX can be 24 fps, 25 fps, 23.976 fps, 29.97 fps, or even 25.001 fps? This is the first and main cause of jerky playback.
The other source of jerkiness is much more subtle and harder to understand. Suppose you play a 25 fps movie on you PC. Well your PC isn’t smarter that any DVD player, it will play it “near” 25 fps because it uses its internal clock, which is inaccurate. But it should not be a problem because DVD players also do that? Bad luck, it is a very big problem, because your video card does not synchronise its speed with the speed of the movie like a TV would do with a DVD player. In a PC the clocks used in the video card (to show the video) and in the PC (to play the video) are completely distinct, thus there always is deviation between them, and then jerkiness is inevitable.
Reclock was created to fix these problems and does so quite well. There's a multitude of clocks in your average PC, keeping them in synch is a nightmare.
From what I understand, XBMC does not yet offer something similar to Reclock, so 24p displayed on a 24p screen could not be perfect.
Keep in mind that you could try XBMC from the Live distribution without problems. Maybe for your videocard/screen combination playback will be already perfect. I wish you just that. :)
An update:
Reinstalled Ubuntu 32 bit from scratch, installed the latest Nvidia drivers (177.80), setup the different custom resolutions at 1366x768.
At 24Hz playback appears far better than at 48Hz (for 24fps content). No frames lost, no judder. I just watched a few minutes of Planet Earth episode 2, the opening scene with the mountain and the sulfuric lake is a tell tale test for judder.
At 48Hz judder reappeared.
Tonight I hope to have time for more thorough testing.
In any case, back on the original topic, the decoding performance it's fine using 32bit.