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Noob
Group: Forum Members
Last Login: 2/15/2008 10:02 AM
Posts: 1,
Visits: 5
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This is a debate that I have been having with a friend of mine and I am hoping someone out there has some real information that can help nail down the truth (even if the truth disagrees with my perception and understanding).
We both play an MMORPG (World of Warcraft).
We, of course, experience lag from time to time.
We both have cable DSL connection to the Internet and we both have pretty quality PC's (CPU and video card-wise).
The question is what causes different types of lag and are they related?
For instance:
My understanding is that FPS is completely independent of network response time.
I can play non-Internet games and videos on my PC with the network disconnected and I get 60fps.
I play online and I get 60fps.
The only time my fps dips below 60fps is when the graphics get "busy" (lots of different complex effects on my screen at once or a whole lot of objects moving simultaneously).
I can play online and disconnect the network in mid-play and I still get 60fps...my character is standing there performing whatever action...never quite completing that action....but still doing it at 60fps display rate.
My friend's understanding is that FPS and network response time are closely, if not, directly related.
He says that if his network latency goes up, his FPS goes down.
I do not have the same experience. I have had network latency of over 2000ms and still my game displays at 60fps.
The reason I think what I think:
If I go to youtube.com and try to watch a video, if my network latency is high, the video display fps will be directly affected because 100% of that video being displayed is dependent upon data being received from the Internet in real time (streaming).
However, if I pause the video and let it catch up (cache), then I can play the video at my 60fps with no problem because now it is playing locally rather than directly from the Internet stream. The cached video is only reliant upon CPU and video card performance to determine it's FPS and not the network.
World of Warcraft is a client that plays locally on my computer (like the cached video). Therefore, so long as my CPU and/or video card are not overloaded I will always get my 60fps regardless of what the network is doing.
The game gets information about the objects on my screen (their relative position, trajectory, statistics like mana and hit points) from the data stream...and that IS reliant upon the network response time; however the rate at which those objects are displayed on my screen (FPS) is NOT reliant upon the network response time. (an example is a moving object that stops moving forward but is running in place...the object has stopped moving in a direction because the network latency has made it so the game client does not have updated information as to where that object should be...but that object running in place is displayed at 60fps)
So, if my CPU and video card are not overtaxed but my network latency is high, then I will get 60fps display rate, however objects on my screen will jump around, freeze in place (but not the whole screen freezing), disappear, run in place, etc.
Conversely, if my CPU and/or video card are being overtaxed for whatever reason, then my whole screen "stutters" and my view of the game slows or halts (freezes intermittently).
My friend thinks that World of Warcraft works like the streamed (not cached) video...if the network "lags" then the video fps will "lag" proportionally.
Sorting out the truth in this matter (what causes each type of "lag") will be extremely helpful in troubleshooting these lag issues when they come up.
Anyone out there have the knowledge (verifiable with sources, if possible) of what the difference (if any) is?
We want to know:
1.) Does network latency cause video FPS latency?
2.) Does FPS latency cause network latency?
Thanks in advance and apologies for the long, convoluted post.
Dyggen
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ELN Board Member, Bigfoot Networks CEO
Group: Administrators
Last Login: 9/8/2008 7:13 PM
Posts: 266,
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I will do my best!
To answer the quick questions:
1.) Does network latency cause video FPS latency?
YES
2.) Does FPS latency cause network latency?
NO, NOT USUALLY
A more thorough answer.
1.)
For "Video" that 'streams'... the codec & network protocol USUALLY allows for dropped packets... OR is dependent on 'retransmission'...
Generally streaming video (not games) show this to the user as a 'blurry' or 'jumpy' picture. (e.g. FPS issues/latency).
For "Games", MOST games also are impacted in FPS when network latency (and/or packet loss) is present, because the "Game Loops" are delayed with the information they need...
That being said, there are a VERY SMALL number of games that do a very good job of hiding the impact... (Call of Duty is one for example).
2.)
The reverse is USALLY not accurate, because the server does not have any concept of FPS.
The Server has the concept of the "GAME TIC"... which is how frequent game state updates.
The Game Tic usually 'happens' regardless of any FPS of any client in the system.
The exception to this might be a Peer-to-Peer Game (if it existed)... where FPS/System performance might impact the global game 'tic' across peers.
Fortunately (unfortunately) this type of game doesn't exist.
Hope this helps,
PEACE,
Tytus
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[ELN]Tytus - EndLagNow.ORG
Member of the Board of Directors of ELN
CEO + Mad Scientist of Bigfoot Networks, Inc.
http://www.bigfootnetworks.com
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Member
Group: Administrators
Last Login: 7/22/2008 10:01 AM
Posts: 11,
Visits: 11
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Tytus (2/15/2008)
The exception to this might be a Peer-to-Peer Game (if it existed)... where FPS/System performance might impact the global game 'tic' across peers.
Fortunately (unfortunately) this type of game doesn't exist.
i wonder if war rock works like that, its a peer to peer FPS game made in korea (where tons of the games they produce in that country are wierd variations of peer to peer)
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