Mark Silva
February 28th, 2007, 11:21 AM
I've been ever so faithful to only using the ProHD jvc branded hdv tapes for my hd100, and still to this day, on every shoot i do, it is inevetable that I will see a digital glitch or dropout at least once, on at least one tape.
I've heard so many praising the sony HDV tapes as being the best with no dropouts at all. I'm not yet ready to plunge for a firestore drive, but I want to ask those of you sticking to the sony hdv tapes (the white ones with purple lettering)
Have you had any dropouts with them?
Tim Dashwood
February 28th, 2007, 12:29 PM
If you have been faithfully using ProHD stock since day 1 then I would suggest that you not switch. You are using the tape stock that is optimized for the JVC heads, so it is as good as it gets. One dropout on the odd tape is not a bad error rate at all.
Remember, there is more going on than just lube. The JVC ProHD stock has the proper S/N ratio for the JVC heads, the proper tension and the extra protective layer to prevent flaking.
http://pro.jvc.com/pro/attributes/HDTV/brochure/PROHD02-tape.pdf
The only way you could improve upon your dropout rate is to use a DR-HD100 hard drive recorder.
Chris Barcellos
February 28th, 2007, 12:34 PM
S/N ratio for the JVC heads
Tim:
Is this really an issue with digital recording of 0's and 1's ????
Mark Silva
February 28th, 2007, 12:39 PM
It would be interesting to see if the S/N ratio is less on the sony tapes than the JVC ones.
Tim Dashwood
February 28th, 2007, 12:56 PM
Tim:
Is this really an issue with digital recording of 0's and 1's ????
It is... Especially with digital recordings dependent on GOP structure. Maybe I shouldn't refer to it as S/N ratio, because it is actually called C/N ratio (carrier to noise ratio.)
Think about DTV satellite reception as a storm is brewing nearby. Some bits in the stream are scrambled causing portions of the image to show blockiness and errors. You won't typically freeze for a whole GOP until the storm is directly overhead and you totally lose the signal.
I've seen similar data losses in HDV that may not necessarily be encoded to the tape that way, especially with the standard "pro" stock. (not ProHD) A second capture attempt can usually capture the offending area properly without error. I see much less of this type of "dropout" with the ProHD tapes. It could also be a tape tension issue, but I would guess that C/N ratio plays a part as well.
It would be interesting to see if the S/N ratio is less on the sony tapes than the JVC ones.
I discussed this once with an video engineer friend of mine and he actually had the specs for all the stocks. If I remember correctly there were huge differences between the Sony and Panasonic/JVC stocks for C/N ratio and tension. I think I jotted the numbers down somewhere - I'll see if I can find them.
Mark Silva
February 28th, 2007, 01:00 PM
What I read about the sony tapes:
3dB higher carrier-to-noise ratio vs. Premium DVC tape
Looks like markertek is now selling them for 12 each. Nice!!
Justin Ferar
February 28th, 2007, 01:05 PM
I can report that I have seen some dropouts using the JVC Pro tape BUT- only on playback. If I go back and play the scene again the dropout is not there confirming that it's not recorded on the tape. This is using the BR-HD50 deck.
Not sure if this is a case of the deck needing to be worked in a little, which used to be the case with some JVC cameras, but since it's not mentioned in the manual I doubt it.
Time will tell as the deck only has a few hours on it.
Peace!
Scott Jaco
March 1st, 2007, 12:22 AM
I've been using those cheap Sony $3 dollar Mini DV tapes for a while. I get the 8-pack for $25.
If you are just doing event videography & seminars, these tapes are fine. I would probably use the more expensive tapes for a movie or tv commercial shoot, but that's working with a much bigger budget.
Keep in mind that HDV1 actually records less information to tape than in regular DV mode. Also, the HDV1 codec uses a shorter GOP than 1080i cameras which means means that if you do get an error, it won't look that bad.