jerky playback

KIPAX

KIPAX

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KIPAX Lancashire UK
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Is jerky playback because my computer isnt powerfull enough maybe?

i took some 50fps and it plays jerky .... i took some 120 fps lovley smooth slow motion.. but if i x4 playback.. same jerky..

ps very new to this.. no idea what i am tlaking about :)
 
It's been a while since I did much with video, but I do know that the undersampling rate had a significant influence on playback jerkiness - particularly when altering the playback speed.
 
Alastair said:
It's been a while since I did much with video, but I do know that the undersampling rate had a significant influence on playback jerkiness - particularly when altering the playback speed.
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Thanks but :) No idea what "undersampling rate" means
 
What sort of shutter speed did you use to shoot the footage??
If you keep your shutter speed too fast, that can make the footage seem 'jerky' ...

So I see you've decided to tip your toes in the video ;-)
 
GooGaBu said:
What sort of shutter speed did you use to shoot the footage??
If you keep your shutter speed too fast, that can make the footage seem 'jerky' ...

So I see you've decided to tip your toes in the video ;-)
Click to expand...


haha yeagh I have a project in mind... Tried my first video in at the deep end... kids football so hard to track... in the pouring rain and at night under poor school 3g floodlights... just about everything as bad as can be..

from looking into it I shot Tv mode at 160 shutter.. shot everything in slow motion 120 fps witht he intention of paying back x4 and selecting any slow to keep as is..

video seems to play back smooth then jerks when shot at 50fps... but in slow mo it plays perfectly.. make it x4 and that jerks as well
 
KIPAX said:
Thanks but :) No idea what "undersampling rate" means
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Neither have I, I just found I'd added it to the captions on one of my sample videos to remind me what I did to smooth it out on changing the frame rate :)
 
Alastair said:
Neither have I, I just found I'd added it to the captions on one of my sample videos to remind me what I did to smooth it out on changing the frame rate :)
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hehe that made me smile :)
 
Unconventional shutter angles will affect playback, ie. shutter speed relative to frame rate. At 120fps you'd normally shoot at 1/240.
 
1/240 thank you

but the 50fps judders and that was 1/160 .... smooth in parts judders in others..
 
I don't fully understand it, particularly when shooting one FPS to playback at another but I think the key will be the shutter angle. A shutter angle less than 180 degrees (at 50 FPS that's 1/100) can have a pronounced effect on movement and action - it's famously a feature of the opening scene of Saving Private Ryan.
 
KIPAX said:
1/240 thank you

but the 50fps judders and that was 1/160 .... smooth in parts judders in others..
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All technical with shutter angles and stuff... never considered those when filming... (now back to reading about all of this)
Guess what I tend to do is just before going to video something.. just Google something like "What is the ideal shutter speed for XXfps video" ...
And then pick it up from there... but maybe if you shot both 50fps and 120fps with the same shutter speed.. that's where the issue might come from??

https://www.reddit.com/r/cinematogr...at_is_the_ideal_shutter_speed_and_frame_rate/

(guessing you are enjoying the 1DX mkII???)
 
I find a set up that works quite well for me is to have my video shutter speed setting (Usually 1/50 with a frame rate of 25) set up on Manual, and my stills settings on Aperture Priority, that way I'm not fiddling around too much and forgetting to change settings for video, so if I'm going to shoot a bit of video I just whack it on M and then balance the exposure with the ISO, take some stills, put it on Av and my settings are still there from the last photo.
Works well for me.

Are you editing the footage or are you saying its jerky when you play it straight off the camera?
 
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Just checking, do you mean an intermittent frame drop (computer speed) or strobing, jerky motion throughout (camera setting).

It sounds like the latter. The judder depends on the amount of motion in the scene.

For shooting 50 fps for display at 50 fps, use approx. 1/100 shutter.

For 120fps, if you're going to display at 120, then a 50% shutter is good. But if you then speed it up by playing back at 4x, it's effectively 12.5% and will be jerky.

You may also spot a lighting issue shooting at 120 - you get a different amount of a 50Hz light output in each frame.
 
Does it matter if I use MORE shutter speed.. does the shudder appear if too little and may as well just use more or can too much have an adverse effect ?
 
Going to experiment later this aft but am guessing the problem is me moving the camers left/right and need to compensate for that somehow?
 
KIPAX said:
Does it matter if I use MORE shutter speed.. does the shudder appear if too little and may as well just use more or can too much have an adverse effect ?
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The judder disappears but the motion blur gets worse.

The other thing you can do is blend frames rather than drop. If you shoot 120fps at 1/120 then blend 2, drop 2, blend 2 drop 2. You get 30fps with a 50% shutter.
 
st599 said:
The other thing you can do is blend frames rather than drop. If you shoot 120fps at 1/120 then blend 2, drop 2, blend 2 drop 2. You get 30fps with a 50% shutter.
Click to expand...

You remember this bit yes?

KIPAX said:
ps very new to this.. no idea what i am tlaking about :)
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Sorry mate no idea what your reffering to.. i am using microsofts movie maker for splitting and changing playback speed..

Have read up as much as I can. unfortunatly i only get a couple of hrs on a friday to play with it all :(
 
180*/50% shutter means that the frame rate is 1/2 the SS... this is the norm and it also applies to playback (i.e. if 120fps is going to be played back at 30fps then you need the 30fps SS which is 1/60th).
But you don't have to apply the 180* rule...

View: https://vimeo.com/138261651
 
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been testing and learning... took a load of video and nothing jerky at 320 shutter and 50fps and 120 fps

so my main question is.. because i am not worried about using up shutter speed for the exposure (its the 1dx2) then is it OK to go over.. is there any adverse effects.. pretty sure I get what you mean but presume these are minimums?

All I am doing is sport so am looking for fastest.. so 5f0ps but maybe shoot mostly in 120fps so i can choose slow or normal playback

given that.. would an approach of 320 shutter and 50fps or 320 shutter 120 fps be ok or do i need to rethink?

will go view the video you posted now .. thnak you :)
 
Right watched the video.. Brilliant thanks :)

edit... yeagh I got it now... rewatched the video and another i found on photogrpahing skateboarding which also helped :)
View: https://youtu.be/2VZMbngPFF8
 
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haha so camera AND video can lie :)
 
done some expermient video.. my arms are hurting from all the wavey about.... going to put all in practice on monday night at local boxing gym... some training and sparring videos put together for one vid... just to see how i get on.. sports person or club promo video is where i am heading A LONG WAY DOWN THE RD :) Going to do everything on tripod with little or no moving of camera or zooming... accept with feet and reposition...... short clips in normal and slow mo... thats for s starting about before i learn anymore.
 
First off let me say I've never used a DSLR for video.
Now that's out of the way, for slow motion to work well it's easiest to shoot at a fps which is a multiple of your final edited fps.
For instance, if your final project is going to be encoded at 30fps then shoot at 60 or 120 fps to get smooth slow motion. Playing the 120fps footage at 25% speed will produce smooth quarter speed slow motion in a 30fps project as each frame in the final piece will be filled with actual footage rather than duplicated/blended frames, if that makes sense.
 
No that's not 100% correct.

If you do a recording with the wrong shutter speed for playback, you increase the strobing (jerkiness).
 
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Yes, I thought the DSLR shutter speed may have an influence too hence the disclaimer :)
Best to decide on the fps of the project then set the shutter speed to suit I'd guess?
 
So not a good idea to do it ALL in slow motion at 120 and 320 shutter then choose which clips to play full speed because then the shutter will be too fast.. I really need to learn to switch shutter speed when switching from 120fps to 60fps...

I did a test video and kept shooting at wrong shutter speed when switching fps.. was put on the spot and didnt have much time so got a bit flustered :( not the only thing that went wrong either... my main aim was to shoot everything on tripod because it was sooooo important to have steady footage... this was in a boxing club and as it was first floor... the floor was shaking as everyone trained so ended up shooting hand held... not brilliant :( i was getting depressed with the whole thing and didnt do any of the setup shots i had intended..

Upshot being i need to be able to take steady pics without tripod and moving about... Suggestions?
 
Ramalama said:
You're looking at a gimbal like a DJI Ronin, not cheap at a grand. There are some cheaper gimbals which are held in one hand like the Zhiyun Crane, but I'm not sure if they can take the weight of a 1DX, they're more for lighter mirrorless cameras like the Panasonic GH5.
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Cheers for that :) But erk :( I do have expensive equipment and dont mind paying out IF I can see it's going to make money for me as indeed all my equipment has... But video.. can't see me spending a grand to make steady video without making money.. might knock this on the head for a bit then... cheers for the input though :)
 
You'd be able to do some nice shots with it though, moving round the boxers etc., all depends how much you're going to get for the videos though as to whether it will be worthwhile.
I did a kids cup final last season with proceeds of the DVDs going to charity, it made £300 from one game, there were five games on that day, if you set up with enough memory cards and batteries you could make quite a bit.
 
Are you playing back the video straight from the source rather than via an NLE. If so try putting it into a video timeline and see if you still get the jerky playback when output .. It may be that you need to render the video into a normal video format that takes into account the increased frame rate. Also what software are you using to handle the video footage. I use FCPX and if you use the Proxy option for playback you can get stuttered playback and frame drop. The only advantage of Proxy is you can edit faster, but at the expense of quality but this is for editing only
 
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