LP vs SP Question

safarijoe

safarijoe

Well-known member
I was on a shoot last weekend and the DVX100a was inadvertandly set for LP instead of SP. My question is will the footage recorded at LP be usable. The lighting was good so there wasn't a noise issue but I'm still concerned. At this point it is unclear if the movie will be converted to film, although it seems unlikely. Thanks in advance for any help you can give.
 
No problem, as long as you digitize it successfully.

LP is more prone to dropouts, but visually it's the same data. They just move the tape slower through the camera so the same footage is crammed tighter onto the tape, which makes it a lot more prone to dropouts. So if you get the footage off the tape successfully (and, if you're using the same camera to digitize as you used to shoot) then you should be fine.
 
Barry - I might be splitting hairs here, but I'm curious -

Is LP actually more prone to dropouts (is the frequence actually higher?), or is it that any dropout that occurs on an LP tape is going to be worse due to data being packed tighter (hence more 'lost' data per dropout)?

In the end it's kind of a moot point - but like I said, just curious.
 
Well, the idea is that the data gets spread over more surface area of the tape. So there could be a case made for both ideas: either 1) SP mode is less prone to visible dropouts because any particular dropout is less catastrophic (affects less of the compressed data) and might more successfully be covered up by DV's error correction, or 2) it's equally prone to dropouts (because tape is tape and the physical flecks of tape are going to behave equally regardless of what data you put on it) but the impact of the dropouts will affect more LP-mode frames because the data's crammed into a tighter space.

Same thing, really; the question is whether DV's error correction is affected by the smaller-by-comparison dropout space. I don't know the answer to that.

What we do know is that LP mode is the least robust way to record, and SP mode is better because it moves the tape faster and spreads the data across more tape, and DVCAM mode is better still because it moves the tape even faster and spreads the data across even more surface area. Thus any particular tape defect will affect proportionately less and less of the compressed data, the faster the tape is moving. (and the tradeoff being, of course, that you can't fit as much footage onto that fast-moving tape, hence why the same tape will deliver 40 minutes in DVCAM mode, 60 minutes in DV SP mode, and 90 minutes in DV LP mode).
 
I suppose you're right, in the end it's the same thing really.
The only dropouts that matter are those we see, I suppose.
Thanks for the details.
 
Thanks Barry, that's a load off. I was hired to replace their camera man and it was my responciblity to find issues like that. When it was brought to my attention, I felt terrible that I missed it. Thanks again for your answer.
 
You must log in or register to reply here.
Back
Top