Replay Camera Video Jelly/Waterfall Effect and Poor Audio

lancer360 · August 20th, 2012, 7:35 PM

I'm using the ReplayXD camera mounted directly to the top of the roll bar using the aluminum billet mount and getting some distortion which I think is coming from the rolling shutter effect. I have put a few layers of rubber electrical tape between the clamp and the roll bar which helped a little but the picture is still not that great. Anyone else have any ideas or know what frequency range the camera is susceptible too? I have talked with Replay and they have more or less given up.

I also purchased the external microphone kit from Replay and while the audio is lightyears better than the onboard mic, it is still very "tinny". I currently have the microphone clipped to the aluminum plate that is my dash. Could that be transferring unwanted or excessive frequencies to the mic? Should I mount the mic differently, or is there a much better microphone to use?

http://www.youtube.com/watch?v=a6TPUJaH0is

**Keith Carter** · August 20th, 2012, 8:08 PM

I think our next attempt to eliminate what you're talking about is to mount it to loose bodywork so that the vibrations aren't transmitted to the camera.

Fred Michael · August 21st, 2012, 5:05 PM

Replay mounts cameras all over the cars in Star Mazda and we don't see video with that sort of problem. Not sure what the problem is but it may not be vibration related.

lancer360 · August 21st, 2012, 6:07 PM

I'm 99% sure it is vibration related to the engine. A previous video I have at Daytona before I added a little bit of rubber between the clamp and the roll bar clearly shows it. The jelly effect goes away for 1 or 2 secs right after a shift and then as the engine climb from 10,000 rpm up to the shift point around 14K rpm the jelly returns and gets significantly worse as the RPM's increase. Different chassis/engine combo's are going to create and transmit the culprit vibration frequencies different. Just because on type of car doesn't have an issue doesn't mean another one won't. Only way to avoid it altogether is to use a CCD camera instead of CMOS, but that increases the price.

Mike Williams · August 21st, 2012, 7:31 PM

[FONT=Monaco]The reason is: The Star Mazda Cars are rotary engines, they are smooth, rotors just spin,

pistons have to stop twice in each revolution we have used the chase cam in the PFM for years I bought a replay xd for our swift 016 it broke in one lap. replay replaced it and we haven't tried it again [/FONT]

Fred Michael · August 21st, 2012, 7:55 PM

No problems on our F2000 cars with the MZR motors with a solid camera mount.
I am not saying that it is not vibration related just that it could be something else as well.

Will Velkoff · August 21st, 2012, 8:23 PM

I run a ReplayXD 1080 on my FF. Have a layer of rubber between the billet mount and roll bar, and the clear plastic over the internal mic and it sounds much better and the video is much better with no shutter. Are you shooting in 720/60 mode?

*ajpastore* · August 21st, 2012, 8:27 PM

I recently found this article. Their explanation and solutions to this problem seem good.

http://www.dogcamsport.co.uk/dogblog...wobble-vision/

-Andy
FV
NER

lancer360 · August 21st, 2012, 8:38 PM

I talked with my friend who is familiar with vibration and ways to dampen it. He said I am most likely dealing with a natural frequency resonance of the combined roll hoop and camera mount system. They are being excited at the right frequency by the forces the engine is emitting which is increasing the amplitude of the the roll bar/camera mount vibrations to the point where it is distorting the camera picture. To fix it he said I have a few choices.

1. Remove, reduce the amplitude of the forces, or change the frequency of the forces being transmitted by the engine. None of this is easy to do in a F600.
2. Change the mass/stiffness of the rollbar/camera mount system to shift its natural frequency to a point that it no longer interferes with the camera. If I was under minimum weight I could look at adding an additional brace or adding some metal, but I can't afford adding more weight.
3. Use some type of isolating mechanism to dampen out the unwanted frequency.

Item 3 is probably the easiest to do, but it will be trial and error to find the right material and density isolator. I'm going to do some searching on Google and Mcmaster Carr and see what I can turn up.

lancer360 · August 21st, 2012, 9:03 PM

I am shooting in 720 at 60 fps.

*TimW* · August 21st, 2012, 9:38 PM

I'm not using this anymore and could be persuaded to sell it. It wold be reasonably easy to adapt to mounting a replay (it used to hold a lipstick analog camera.

fvracer27 · August 22nd, 2012, 7:50 AM

Quote:

Originally Posted by lancer360

I am shooting in 720 at 60 fps.

I would record in 720 at 30 fps and take the tape out between the mount and bar. Is there a reason you put the tape there? Does the mount fit exactly on a round tube or is it more of a oval tube? This seems to happen when mounts are not completely solid and with FF,FC and FA once they reach a certian RPM. I sell Replay and have had absolutly no problems on FV and SRF mounted with the Billet mounts solid to the bar. I have not tried other cars myself yet but I have one going on a FE in a few weeks and will let you know results.

Mark