60 and 90 minute mode on DV tapes - differences?

[geek rock]

folks..

just wondering if anybody has a link or description or something of the differences between an SP and LP mode of recording on a miniDV camera? i know the audio is 48khz and 32khz, but are there video differences as well?

i'm going to be doing some filming of a band, hopefully, and i dont really fancy changing tapes mid-set.. i'd prefer to not worry about it (the shows are usually 60-70 minutes so would fit nicely on a 90 min tape).

is there any noticable audio and video quality lost in 90 minute mode? would you bother to encode this mode as a DVD mpeg?

apologies if it sounds like a dumb question..

thanks!

-Mark

[tag]

Here's my take on this:

Digital is digital and there's virtually no difference in video quality between SP and LP.

The problem with LP, however, is that it pushes the DV envelope, so to speak. The result could be that the tape won't play in other camcorders immediately after recording (if it plays at all, there could be a significant amount of noise) and/or won't play in the camcorder in which it was recorded sometime later. IOW, LP is not the mode to use for archival purposes.

I've heard others recommend that stuff recorded in LP mode be dumped off to a computer or dubbed onto two tapes recorded in SP mode as soon as practicable.

[geek rock]

well i don't plan on doing any sort of editing at all with the footage once i've made my DVD, so a hard copy of the DV tape won't really be necessary. thanks for the advice. anybody else have suggestions?

[Curt]

LP mode will have more video dropouts and poorer quality audio than SP mode. It only takes a few seconds to change a tape. You could squeeze it in between two songs and it would be a lot less noticeable than a poor quality video. If you know the band, they might even add an extra 15 second break between two pre-planned songs in the set just so you could change the tape. Tape is cheap, and high quality is good.

Curt

[mikesbytes]

On the digital tapes, there is no difference between the video quality on the SP vs LP mode. The video specification is identical.

The differences are that the extra features have been removed, for example there is no longer 4 sound tracks vs 2 sound tracks. The removal of these features has made up the room required for the 50% extra videol

There is also suppose to be a problem with playback of the tapes in other camcorders, but I have not had the chance to test that.

[MpegEncoder]

LP mode will have more video dropouts and poorer quality audio than SP mode.

Perhaps you would like to support this conjecture with some facts. From what I've read, LP simply packs the data tighter on the tape. What makes you think there will be "dropouts" and "poorer quality audio"? Also, what do you mean by "dropouts"?

[adam]

The quality of the video in SP and LP is identical. I have heard of drop outs in DV before (tape head gets stuck for fraction of a second) but I don't see how this could occur more often in one recording mode than in another.

As mikesbytes said, the main difference between SP and LP is the extra features like those that allow you to dub additional audio tracks. If you are transferring your DV to DVD or another recordable format, these options aren't even necessary.

As far as compatibility, LP footage won't play in DVCAM or DVCPRO VTRs other than the DSR-2000, and SP footage will play in any of the VTR's. Unless you have this professional level equipment and need universal tapes, then compatibility is a moot issue as well.

[daamon]

Hi geek rock,

I've captured footage for a friend's wedding and 7 different holidays over the last 4 years - all in LP mode on my DV cam and have never had any problems.

Thanks to this (excellent) site, I'm now in the process of (finally) freeing up my DV tapes by transferring the footage to PC to ultimately end up on DVD. So far, I've been extremely happy with the results (i.e. quality) that I've achieved with my DVDs.

Good luck.

[sitlet]

everybody on here is right. technically LP and SP mode are the same quality. but with LP mode, you are running the risk of getting dropped frames and blips in the audio. it doesnt happen a lot, but ive seen it happen. and in LP mode, the compatibility of that tape in other players is less. i have some LP tapes that play like crap in my standalone JVC minidv deck.

personally, i most always use LP mode. unless its something very important to me, then i will use SP mode if i can. 95% of my recordings in LP mode are perfect. but i do have a few Sony tapes that are about 2 years old, and LP mode doesnt work good with them. for every 30 mins of footage, i probably get about 10 dropped frames or so.

[x21x]

I would try to go with the 60 min tapes if possible, but if you feel that you might not have the chance to change tapes then do go with the 90. I use 90 minute mode all the time, the only problems i have ever had are just some very small artifacts on the screen( probably because i have reused the tape like 5 times). Hope this helps.

[monstermash]

As already posted there is no difference other than the fact that the information is packed more tightly onto the tape (tape speed about 66%).

Your best bet is to get hold of some 80 min tapes or get hold of some DV cam tapes (90min on standard play) as these are designed for DV cam cameras which run at 150% compared to a standard mini DV cam camera.

DV60 tapes 61-62mins SP / 92-93min LP

DV80 tapes 81-83mins SP / 122-125min LP

DV Cam 60 60min dv cam / 90min SP / 120min LP

IMHO LP isnt worth the hassle as I know people who master in this format and if a standard glitch (usually 5-8 frames in SP) occurs then in LP it can last for upto 10 seconds, dont ask me how but this is what Ive seen.

If you need any other convincing look at a sp/lp vhs recording (same principle).

Also why would Sony produce a camera that runs the tape 50% faster and incorporate it in their PRO range (DV CAM), if it wasnt for stability.

[geek rock]

thanks for the advice, people. looks like i'll give LP a try. as i say, i'm not planning on doing any sort of editing later on, i'll purely just dump the original tape to my computer and burn a DVD from there.

-Mark

[BSR]

Excerpt from DV.com. I remember seeing a more technical explanation for it but couldn't find it.

Actually the same amount of digital information is written to tape, only on a thinner track. This gives you more recording time per tape but the quality of playback is exactly the same unless you have trouble reading back the recording because of the thinness of the track. The actual speed of the recording head is practically the same because the video drum still spins at 9000 rpm. The track width drops from 10 to 6.7 micron because the tape goes past at a slower speed. (I think the video head itself is actually 12 micron)
If you record and playback on the same well adjusted camcorder you should see absolutely no difference in quality between LP and SP speed.

Recording in LP mode increases your chances of dropouts due to tape quality and tracking problems.
Unlike analogue systems the DV cams can correct small dropouts because there is redundant information recorded on tape. But larger dropouts will become visible - which is when the playback quality suffers.
Tracking problems will be more likely to occur if you try to play the LP tapes in another camcorder as the alignment is more critical.
Also as your camcorder gets older and the tape alignment changes slightly due to wearing on the drum and tape guides you may find you have problems playing back old LP recordings.

[turk690]

As tapes are more or less cheap, and because of possible problems with playback compatibility on other machines, SP should be the way to go. On an older Panasonic NVDS28EN camcorder still in use this is how I do it. But on a newer Canon it is just so much hassle dismounting the camcorder from the tripod in midshoot just to eject and change tapes from the camcorder bottom one just has to use LP to get 120mins from an 80min tape. Is this design deliberate?

[mikesbytes]

Quality identical between SP and LP

SP
Pros: Less risk of dropout, greater compatiblity between camcorders, tapes are cheap so who cares
Cons: Max continious 80min

LP
Pros: Max continious 120min
Cons: slightly greater risk of dropout, lower compatiblity between camcorders

I've never had a dropout in either SP or LP mode, but wouldn't like to risk it in the middle of capturing a friends wedding