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Canon VIXIA Series AVCHD and HDV Camcorders
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Old July 17th, 2007, 02:23 AM   #1
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Call On All Hv20 Owners - To Test For Dropouts

CALL ON ALL HV20 OWNERS - TO TEST FOR DROPOUTS

there have been quite a few reports that the HV20 randomly drops out every now and then.

I myself have replaced my HV20 twice because of this issue. i tested with several different tape brands in both HD and standard versions... i used head cleaners and one HV20 actually started chewing tapes after 4 hours of use and two head cleanings....

what is a drop out?

it's when the video cuts out for a second or two.
usually this is because the heads on the camera need cleaning and a simple head cleaning tape will fix it.... but this seems to be an issue with the HV20 it's self.


i think this issue mightn't have been noticed on a large scale for a couple of reasons... the dropouts are so sporadic that people who use the camera only a little bit might never come across it... some people mightn't be aware what dropouts are or that it's a problem with the camera... people using the camera for short takes ( 2 min, 3 min, 30 sec) might have just been lucky and not come across it yet.


how do i test?

the easiest way i've found is - put your camera in front of your TV and record a full hour of tape - the constant movement and sound of television make a dropout easy to detect.

then import your footage onto your computer - make sure you've got 'create new clip on start/stop' selected - after you've imported your footage, if there is more that one file, then you've had a dropout.

you can got to the same time in the time code on your tape to check it really was a drop out and not something else...

report back with what brand tape you were using and how many drop outs, if any, occurred in an hour.


i've found -

JVC PRO HD - 7 or more an hour
SONY HD - at least 1 an hour
SONY Exc - at least 1 an hour
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Old July 17th, 2007, 03:47 AM   #2
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Hi Patrick...........

I'm not entirely sure there was actually a question remaining at the end of your post...........

However - It would seem that whatever brand of tape you are using when shooting HDV, the incidence of "dropouts" increases exponentialy the longer you shoot. It is an inherant problem with the "GOP" thing to make HDV work with tapes (never a stable medium).

If I get by with only 3 dropouts on a 60 minute tape on my XH - A1, I consider myself lucky - and I use a cleaning tape before replacing any used tape in the machine.

The same rate is happening with my HV20.

The Panasonic tapes you'll see mentioned everywhere on this site seem to have the best user feedback, but at the end of the day, you ARE going to get dropouts using tape, and at HDV levels, they are VERY noticeable.

What more can I say? It's an extremely poor medium to capture such brittle data streams, and as soon as someone comes up with a cost effective way of doing it better, you'd better believe the entire industry will stampede in that direction.

CS
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Old July 17th, 2007, 04:47 AM   #3
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My HV10... I recorded and imported 30 tapes, only noticed 1 dropout in all the footage...
My HDR-FX7, imported 12 tapes and noticed 3-4 dropouts, but that was a tape I dropped in the dirt... so I don't really count that.
My old Canon Elura 2... I never saw a dropout.. ever... in 30-40 tapes+

I mixed tapes on the HV10 and Elura2, even re-using some

The FX7 has gotten Sony Premium and Sony HDV Master Tapes... that's it...

I record my tapes to the end or very close to the end (52-58 minutes)
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Old July 17th, 2007, 05:38 AM   #4
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chris... 3 dropouts an hour is normal?!!?!
i never had a drop out with SD DV stuff. i am new to HDV though...

i have a friend with the sony A1P HDV camera. he's never had a drop out ever.... that's why i though the 3 HV20's i've owned and the other ones i've been told about and maybe all HV20's were faulty.

the people at the camera store i get my stuff from said it shouldn't be happening.. and they know there stuff. they were the ones that told me other people are having the same problems with the HV20.

are you sure your HV20 and A1 aren't faulty?
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Old July 17th, 2007, 07:07 AM   #5
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hmmm

The only drop-outs I've noticed are when there's a shock to the camera:

I shot a band (continuous for about an hour, 2 other cams also shooting) and I was crawling around on the floor getting funky angles and jarred the camera pretty good once and it dropped maybe 4 frames.

This past weekend I was shooting a short and got too close to an actor who spun around and walked right into the camera. I was really disappointed about that drop-off, because it was damn funny.

Jason
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Old July 17th, 2007, 09:57 AM   #6
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The day Canon releases an HV20 like camera that records to flash card can't come soon enough.
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Old July 17th, 2007, 10:00 AM   #7
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You will always get dropouts with HDV because tape, no matter how expensive, will always have imperfections that disrupt recording. HDV uses MPEG2 compression with a 15 frame GOP (Group of Pictures) which means that the slightest glitch in the tape coating loses you 15 frames.Whereas in DV you might see a flash frame or a brief flurry of coloured pixels, in HDV you lose at least half a second of recording. This is one of the reasons why keen HDV users like to record direct-to-disk or have a backup recorder or second camera for important events, just in case.

I've noticed with my two Sony HDV cameras that you will see a few dropouts on the first couple of tapes you use, and thereafter you will rarely see them.

Three dropouts in 60 minutes is either very bad luck or evidence of some other problem - possibly the wrong brand of tape or excessive use of head cleaners. I use Sony Premium tapes in my 2 year old Sony FX1 and I have not yet needed to use a head cleaner.
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Old July 17th, 2007, 10:30 AM   #8
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Quote:
Originally Posted by Joe Busch View Post
My HV10... I recorded and imported 30 tapes, only noticed 1 dropout in all the footage...
My HDR-FX7, imported 12 tapes and noticed 3-4 dropouts, but that was a tape I dropped in the dirt... so I don't really count that.
My old Canon Elura 2... I never saw a dropout.. ever... in 30-40 tapes+

I mixed tapes on the HV10 and Elura2, even re-using some

The FX7 has gotten Sony Premium and Sony HDV Master Tapes... that's it...

I record my tapes to the end or very close to the end (52-58 minutes)
One thing I think your missing in the equation is the length you shoot non-stop. The dropouts become prevelent when shooting 40 to 60 minutes non stop. There are probably very few peope who do this. I do because most of my video is shooting music sets and I never pause or stop the camera.
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Old July 17th, 2007, 10:50 AM   #9
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so far i'm getting drop outs when using panasonic master series tapes ( out of 2 tapes - more then several drop outs per tape ) .. when i use the cheap panasonic's ( $3 ea) out of 3 tapes i've had 2 drop outs
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Old July 17th, 2007, 11:21 AM   #10
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What tapes? I had an awful time with Fuji tapes in my Sony. No dropouts since switching to Sony "HD" tapes.
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Old July 17th, 2007, 11:54 PM   #11
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Patrick (and others)............

No, I don't think three drop outs an hour is "normal", it's just what I'm getting (sometimes). Occasionally I'll get a clean run end to end, sometimes one, sometimes more.

I'm still working my way through a batch of Panny DVM63MQ tapes before I upgrade to the newer version, there must be a reason Panny upgraded this tape stock. I'm hoping that will improve the situation.

As for other factors - both my cameras take a bit of a battering, and we share the house with 8 cats - a sort of giant fur ball with a house around it. Either of these could be taking their toll.

Before I went HDV I had only 4 dropouts in 7 years on my XL1s, and that took more of a battering than my current cameras.

As for using a cleaning tape "too much" well, I'm trying it to see if that improves the situation, so far it hasn't (but I'm only about 6 tapes into this trial).

I guess the bottom line for me is that, untill someone comes out with a guaranteed perfect tape from end to end OR a diffent recording mechanism altogether (I am SERIOUSLY thinking of going over to a Firestore unit) then this is what I'm going to have to put up with on HDV.

As I said, tape will never be perfect and long GOP data streams require it to be just that - ergo, it must fail occasionally, it's just a question of how occasionally that is.

One test you might like to perform will give you an idea of what is going on - go back to your shooting the telly test, but shoot it in SD. If the whole thing is perfect do the same test with the same tape and shoot it in HD. If you get dropouts in HD and not SD it's ...............interesting.

CS
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Old July 18th, 2007, 12:21 AM   #12
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Originally Posted by John Hotze View Post
One thing I think your missing in the equation is the length you shoot non-stop. The dropouts become prevelent when shooting 40 to 60 minutes non stop. There are probably very few peope who do this. I do because most of my video is shooting music sets and I never pause or stop the camera.
I go between 7-10 min at a time, sometimes 20+ min straight... still no dropouts that I've noticed...
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Old July 18th, 2007, 01:46 AM   #13
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Using my HV20 with JVC HD tape, I've noticed the dustier the outdoor environment the more dropouts occur.

Indoors over 4x60min tapes, 2 dropouts. Shooting 2x60min tapes outdoors in a slight breeze in the Arizona desert, 2 or 3 dropouts per tape. During playback one at the 50min spot on the last tape, goes blue screen for 3 secs.

I believe very fine dust getting into a cam, can get onto the tape path and dropouts result.
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Old July 18th, 2007, 09:14 AM   #14
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dropouts in HD versus SD

I've read a few posts that talk like the tape will be more sensitve to dropouts in HD versus SD. Why would this be since the data rate is the same. The same number of bits per inch are being recorded in both modes. Does the "GOP" thing only come into play in HD mode and this might be why we're seeing more dropouts with the HV20. Obviously most people are shooting in HV since they bought an HD camera and even if downsizeing to SD the quality is so much better than shooting with an SD camera.
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Old July 18th, 2007, 09:43 AM   #15
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John ...

Yes, the data rate is the same for both DVand HDV, but an HD frame is about 1.5 MegaPixels while an SD frame is about half a MegaPixel - roughly 3 times as much information is being squished on to the same bit of tape for HDV by the use of MPEG2 compression.

I'm not an expert on MPEG2 codecs, but it works something like this :

Instead of recording every pixel in every HD frame, only one complete frame is recorded (called the I-frame) in a group of 15 frames (the GOP), followed only by the pixels that have changed in the following frames . On playback, all of the frames in the GOP are reconstructed from the I-frame and the differences, but if the I-frame is wiped out by a tape dropout then the group of frames cannot be reconstructed, leaving a big hole in your playback.

So you'll notice many more tape dropouts in HDV than you will for DV.

Tony
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