Why does 30 fps look smooth in a video, but choppy in a game?

[adi518]

I started capturing some fsx gameplay lately and I couldn't help but notice this weird phenomena. In-game, if I run @ 30 fps, it looks choppy and slow (no one likes 30 fps in their game, right?). However, when I upload my videos to YT, they become super smooth. Why is that? What is the difference that makes 30 fps videos look smooth, but choppy when playing a computer game?

[KOtech]

<p>Capturing software uses computer power whereas the game may start lag. (Or are you asking something else?)</p>

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[911^NEmeSis]

I think it's more that you feel the choppiness as you move your mouse. I know for a fact that I can't do things like bunny hop and my mouse feels very unsmooth at 30fps compared to a 100 for example.

[adi518]

<p>Capturing software uses computer power whereas the game may start lag. (Or are you asking something else?)</p>

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Nah, say I lock my fps @ 30 (just for 'fun')... it seems "slow". It doesn't give you the smooth feel 60 fps does. Well, question is, why does in a 30 fps youtube video it is!? :D

[bartekxx12]

I'm not exactly sure but I would assume these 2 things play a big part in this - 

A YouTube video or just videos in general, if they are 30FPS then it's constant 30FPS, each frame is shown exactly emm... 0.0333s after each other. In a game the times may be different, where overall you saw 30 frames in a second, but 25 of these could have been in the first half of the second and the other 5 in the second half meaning it's not consistent resulting in choppiness.

 

Another thing is input lag, if you are running a game at 30FPS and move your mouse (assuming no delay for the monitor to display the picture, no other delays at all, just pure FPS) then your input will be shown on the screen 0.0333s later. If you are running at 60FPS then the next frame after your input will be displayed in 0.016667s meaning you have to wait less for whatever you did to be shown on the screen resulting in a smoother experience. 

[Lukiose]

This is because frame latency isn't as perfect as you'd think, it actually fluctuates alot in that one second, and it does affect your experience of visual smoothness. (Pics taken from another thread)

For example, this would feel very smooth whereas

\

This would not feel as stellar, despite the frame latencies being roughly the same.

So on a youtube video, this margin of error is presumably negated, as it is from a digital playback rather than real-time processing, hence the "Youtube 30FPS > Real-time 30PS"

[samuel]

This is because frame latency isn't as perfect as you'd think, it actually fluctuates alot in that one second, and it does affect your experience of visual smoothness. (Pics taken from another thread)

For example, this would feel very smooth whereas

\

This would not feel as stellar, despite the frame latencies being roughly the same.

It's most noticeable in AMD CF builds. See frame times by PCPER.

[Lukiose]

It's most noticeable in AMD CF builds. See frame times by PCPER.

Right... Are you assuming i wouldn't know the issues with xfire? In case you didn't know yet, the 2 graphs are taken from http://linustechtips.com/main/topic/16010-radeon-pro-a-brand-new-software-that-fixes-most-xfire-issues/page-3?hl=%2Bradeon+%2Bpro#entry312349. 

[JordanMac]

its because at 30 fps you move your mouse and it takes 1/30 of a second to load the next frame of you mouse in the new position, at 60 fps it is 1/60 of a second and so on so the higher the fps the less lag between you moving you mouse and seeing the results. however when watching a film you are having to input, therefore this delay is still happening between when the computer sends the frame and the monitor displays it but because you have no input and don't control the frames that are being sent, it seems instant.