SP vs LP
 

In DV land, what are the true differences between SP and LP recording speeds? In analog land you lose picture quality when you go to the slower speeds. But with MiniDV on my fabulous XL1 camcorder I cannot tell the difference in image/sound quality between the two speeds at all. I assume that the heads are writing the same exact digital data regardless of what speed you are recording in. So the picture and sound should not suffer at all.

So what are the differences?

You are correct. There is no difference in quality. The difference
is in how it is stored. I don't know exactly how it differs, I think
it was the speed at which the tape was written. There was a
thread about it last year. Try searching on it.

There will be absolutely no difference in the quality of the picture or sound. Because the tape is moving slower, each piece of information is written to a smaller area. Because of this, there is a greater risk of dropouts caused by data not being read correctly. The greater risk of dropouts, and greater incompatibility between cameras, is the main reason most people recommend avoiding LP. Otherwise, you can't tell the difference between SP and LP.

the difference is in the correction bits
in SP mode for 9 bit there are 6 (parity) correction bits
in LP mode there is only a bit for 8 bits
so you can write about the same data with lower speed

BY Francesco

Francesco's and Ed's remarks jibe with my knowledge. Sampling rate is the same, tape speed is slower, data is ultimately written to a smaller space on the tape.

If you plan to use LP mode for critical work I would suggest using "pro-grade" tapes with a higher density of magnetic substrate such as Panasonic's "Master" line of tapes. You can find these a a few online resellers such as www.taperesources.com. This would help to minimize drop-outs.

Also, one last comment. On occasion I, an others, have had trouble playing-back LP footage on equipment different from that which recorded it. For example, if I record LP footage on my GL1 I -might- have some trouble capturing the footage on my Panasonic deck. This has only happened to me twice but since I rarely use LP I would imagine that statistics are not in my favor. If you plan to use a cam/deck or cam/cam combos for aquisition/capture you'll want to do some testing before committing to LP for a shoot.

I'm going to add my two cents here. I'm sure you 've heard the old saying "tape is cheap?" In my (hopefully) humble opinion, it's not worth risking the dropouts and/or incompatability issues to ever bother shooting in the LP mode. True, you end up with twice as many tapes at the end of the day, but on the other hand, shorter tapes are easier to work with when you're editing.

Bill S.