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Dropped Frames During Loud Rock Concert

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Torben Suhrke
Dropped Frames During Loud Rock Concert
on Nov 23, 2009 at 12:06:07 pm

Hello,

we put our new KiPro to the test this weekend by recording a Rock Concert. We have the KiPro equipped with the 250GB Harddrive. We recorded using SDI-In via the normal ProRes-Codec in 720p50. After about 1 and a half hour we expierenced Dropped Frames Warnings in the display. The recording stopped and we had to press the record button over and over again. The harddrive was filled to 50% by that point.

I suspect two possible reasons for the failure:

1. Heat-issues. The drive felt pretty hot when I touched it.
2. Vibrations. The concert was very loud. I tried to shock-absorb the unit by placing some rubberfoam beneath it, but it didn't work out. I guess the vibrations due to the loud bass were "all around" so to speak and were not only transmitted via the table the KiPro was standing on.

Has anybody experienced something similar?

Best regards,
Torben Suhrke


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gary adcock
Re: Dropped Frames During Loud Rock Concert
on Nov 23, 2009 at 3:58:39 pm

[Torben Suhrke] "Has anybody experienced something similar? "

I supervised a 10 KiPro capture last week for the MTVu "Woodie Awards" (9 cameras + PRG master) and recorded the show for on all 10 units for over 3 hours at 1080 60i without issue.

The Drive Module would not have failed without some warning from the KiPro before hand.

You do not mention how you were working with the KiPro- was it onstage( my guess) or

"1. Heat-issues. The drive felt pretty hot when I touched it. "
All hard drives heat up when being continuously written to. The drive modules are specifically designed to vent that heat, so they do tend to feel warmer than say a desktop drive which has much greater cooling capacity due to design. Please tell me someone did not use it to lay papers or a script on, as that would decrease the cooling capabilities.

"2. Vibrations. The concert was very loud. I tried to shock-absorb the unit by placing some rubberfoam beneath it, but it didn't work out. I guess the vibrations due to the loud bass were "all around" so to speak and were not only transmitted via the table the KiPro was standing on."

All recording media is susceptible to failures depending on the conditions, and spinnning disks are no exception, If your recorder was on or just in near proximity to the stage the bass or drums could have easily been affected the record head- just like it would on any tape deck or other physical mechanism would have been. Explosions on stage as part of pyro or fireworks would have the same effect. I have even seen it in orchestral performance when the tympani and or gong were struck profoundly.

For the MTV shoot I was on a folding table in the camera truck about 100 ft from the back of the stage.

My rule of thumb is to place the recording device as far BEHIND the stage as possible to help prevent this kind of issue.






gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL


http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Torben Suhrke
Re: Dropped Frames During Loud Rock Concert
on Nov 24, 2009 at 1:55:39 pm

Thanks guys,

upon further inspection the unit showed some recording artefacts even in normal recording conditions. The picture was jumping up and down for about 3 scanlines in total.
I guess I'll have the unit replaced.

Btw the distance to the stage was 10 meters. But it was not possible to place it behind the stage.

Thanks for your advice,
Torben Suhrke


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gary adcock
Re: Dropped Frames During Loud Rock Concert
on Nov 24, 2009 at 2:59:27 pm

[Torben Suhrke] "upon further inspection the unit showed some recording artefacts even in normal recording conditions. The picture was jumping up and down for about 3 scanlines in total.
I guess I'll have the unit replaced. "


I would check it in a Non concert situation before sending it back.
The skipping could have been as a result of the vibration also. See the distance between the R/W head on the drive is measured in microns so the vibration can have minor effects on how the drive was written too.

Let me say that you need to test, test, test with any new device to see if it works in your workflow or in the environment that your are working in. Shooting and testing your setup during sound check often will flag any record or playback issues.

The fact that you thought to put the unit on padding meant You knew or guessed that it was getting too much vibration and that is not ever good for to record to any spinning disk in that type of environment. My guess is that another 20meters of HDSDI cable would have solved most of the issues by allowing you to move the record farther away from the stage, as is common for most concert FOH video production.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL


http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Jeremy Garchow
Re: Dropped Frames During Loud Rock Concert
on Nov 23, 2009 at 7:14:51 pm

This would be the prefect scenario for the SSD hard drives.

Jeremy


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Fred Jodry
Re: Dropped Frames During Loud Rock Concert
on Dec 1, 2009 at 3:15:50 pm

"This would be the perfect scenario for the SSD drives", J Garchow
Unless of course the vibration goes up enough to make them and the other equipment buy the farm. I`ve been thinking about using an outfitting of SSD to increase the speed of my Mac but aside from the rather pressing price of the drives, some manufacturers of SSD drives try to foist high density memory types on the unsuspecting buyer. Trying to find the right boot host cards and utility cards (hopefully the same card) can also get in the way.


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Tim Kolb
Re: Dropped Frames During Loud Rock Concert
on Nov 25, 2009 at 2:23:35 pm

I've seen this with hard drive recorders...as Gary reminded me recently, hard drives and vibrations aren't particularly compatible...

:-)

It has gotten to the point where most camera people have to make sure they've visited the restroom before the show and most anyone in the venue working the show has ear plugs if they don't have double muff headsets.

In a recent show we did, the low frequency vibrations were so bad that my closeup camera couldn't get any closeups because even if the camera person attempted a 'float' or a lock down, the platform was vibrating so bad that the shot was unusable...

It's not a stretch to picture a hard drive malfunctioning at the FOH position in this environment.

Being in a truck sometimes feels isolated...but then there are times when that's a good thing.





TimK,
Director, Consultant
Kolb Productions,


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