FORUMS: list search recent posts

rolling shutter effect or compression issue?

COW Forums : Compression Techniques

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Vic Noseworthy
rolling shutter effect or compression issue?
on Feb 7, 2010 at 10:51:12 am

Hi,
I'm seeing an effect in my uploaded video and I'm not sure if it's due to the fact that I have a CMOS camera (Canon HF 10) with a rolling shutter, or if it's because I'm not compressing my video properly. If you think you can tell, would you be kind enough to take a look at it and give me your thoughts? The link is below.
Thanks very much!
You should see the effect I'm talking about right at the beginning, in the first panning shot. You'll notice the video kind of breaks up along the horizontal... kinda jittery.
Here's the link (scroll down a little and you'll see the video):
http://www.dreamhousevideos.com/infopage.html
Vic
(Or am I being too picky?)


Return to posts index

Craig Seeman
Re: rolling shutter effect or compression issue?
on Feb 7, 2010 at 3:58:56 pm

I'm not seeing anything that looks like a rolling shutter issue and your camera movement is nice and slow. The opening pan has a slightly "staccato" look but there are a few reasons that could happen.

Although I shoot with Sony EX most of the time, we often use a Vixia HF10 and HF200 as b cameras. What mode are you shooting in? I'd recommend 1080p30 over 24 (might help the pans) and shooting progressive avoids having to deinterlace.

Exactly what are your compression settings? Include everything (every single detail helps). It could be as simple as too high a data rate such that some viewers might have playback issues.



Return to posts index

Vic Noseworthy
Re: rolling shutter effect or compression issue?
on Feb 7, 2010 at 6:43:55 pm

Hi Craig.
Thanks for your response. I've been sizing up my original footage, and I'm pretty sure the problem is originating there. I do see the same 'staccato' effect in my pans. That's why I was thinking the problem is with the type of camera (CMOS). I'm wondering would a higher end CMOS camera lessen or eliminate the problem. At the same time, I do see similar 'artifacts' in much of the online footage I see. That's why I wonder if I'm just expecting too much?
As for my compression settings, I went with a preset with Sorenson Squeeze, and the settings are as follows (it's been awhile since I posted that video, so I hope I'm correct here):
Data Rate: 480 Kbps for video; 64 Kbps for audio (sample size 16, 22050; stereo seems to be the only choice)
Framerate is 1:1 (and my original was shot in 1080i60)
I compressed for Flash 8 using On2VP6Pro (2-pass VBR)
Keyframe every 60
I hope this helps. Though, as I've said, I'm thinking it must be in the way the original footage was captured. I will try 1080p30 and see how it looks.
You mentioned that a number of things could cause the staccato effect. Can you be more specific?
Thanks very much for your help.
Vic


Return to posts index


Craig Seeman
Re: rolling shutter effect or compression issue?
on Feb 7, 2010 at 7:42:02 pm

The "staccato" effect can have several causes. One is panning too fast for the frame rate. It's a common issue when people pan too fast when shooting 24p and they're not familiar with the cinematographic rules of panning. It can happen at 30p. It's not likely to happen at 720p60 or 1080i60 though. Since you shot at 1080i60 then that probably isn't the cause. BTW this is a general issue not specific to CMOS or low vs high end cameras.

Another common cause is too high a shutter speed. Some call it the "Saving Private Ryan" effect since it was prominently used in that film but it's not an uncommon effect in action or horror films. It can create a "nervous" feeling and tension in fast action scenes. It basically is about "motion blur." If the shutter is open longer the motion is blurry/softer/less jarring. One might shoot at 1/60 for i60 on the other hand if one shot at 1/1000 one might have the staccato effect. I noticed the contrast range was more than the camera could handle on some shots. Whites were blown out (the sky or the side of the house on exteriors for example). If your camera was on auto shutter it may move to a higher shutter speed to compensate as doing that darkens the image a bit. If you see the issue pre compression this may be one of the causes.

One of the keys to shooting with many of the Vixia cameras is to go into the menus and lock everything in in manual mode to avoid it making the wrong decisions.

On Deinterlace, I don't have Squeeze 6 but in 5 it has variations on Blend and Discard Field. In your case blending might help in cases of motion.

A key thing you don't mention is your targeted frame size and what kind of deinterlacing (there are many) that you used. Can you post the frame size and the deinterlace setting in the preset? I'll have more to say once you post that info.

In Squeeze, for Flash I would choose MainConcept H.264 f4v or mp4 and multipass over On2VP6. Either f4v or mp4 will work in Flash but mp4 might allow for greater repurposing (client wants to view the file itself on their desktop for example).

I'd also consider upping the sample rate to 32khz or 44.1khz. Even if you need to target a low data rate I'd say 32khz mono would be OK. 22.050khz is really for voice only or very low fidelity music. Many people have good "gaming" speakers hooked up to their computer so they might hear the difference.



Return to posts index

Vic Noseworthy
Re: rolling shutter effect or compression issue?
on Feb 8, 2010 at 1:33:44 am

Hi again, Craig.
And, thanks again for the info. I'm about to do some test shooting using a slower shutter speed to see if that helps. I'll continue to keep the frame rate as high as I can (as you mentioned, I've been shooting at i60, so that's not likely causing my problem).
You mentioned it's a good idea to all use manual settings on the Vixia. I will set the camera to 'shutter priority', and use 1/30 sec. The camera then sets the aperture. (Though, there is still some control over the "exposure", but I don't know if the adjustment is for the gain or the aperture...? The manual isn't clear on this. In any case, I'll use 1/30 sec.)
You were wondering about my 'target frame size' and the kind of de-interlacing I used. The de-interlacing was done right in Final Cut Express, so whatever that program uses is what was used. I don't believe it gave me various options. As for target frame size, I'm not quite sure what you mean. I mentioned previously that my settings of output into Flash included a resolution of 640x360. Is this what you mean?
I will play around with some of the compression settings once I've done some testing with my camera settings. In the meantime, thank you again for your kind assistance.
Vic


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]