The second elephant in the room

[Jeremiah Black]

Chris,

I think you’re confused on some points. Obviously the tape transport can only record DV signals since DV tape is a 25 mb/sec medium. This isn’t so much “an elephant in the room” that panasonic forgot to “nail down” as it is a completely obvious and self-evident fact regarding the limitations of DV tape. This is why the camera has options- record a 25mb/sec DV signal to tape, or, if you’d like to shoot HD, then record it to P2 cards, since mini dv tape can’t handle that kind of data rate. Or shoot to a hard drive, if you like. Obviously shooting to P2 cards is the safest and most flexible and rugged was to shoot (no power supply needed, no moving parts, greatly reduced possibility of damage, etc.), but P2 cards are not cheap, so if you’re on a budget and can do it, maybe drives are the best solution ot get you through a no budget project.

The data rate is indeed 100 mb/sec- a data rate the ALL portable drives can handle (1/4 the capabilities of simple firewire 400). An ipod can handle that.

jeremiah black
dual 2 gig G5
2.5 gigs of RAM
Decklink Extreme capture card

[Blub06]

Honestly, I had no idea that this new cameras tape function was DV only. I don

[Kevin Dooley]

Hey Chris,

I think you’re confusion comes from the fact that DVCPRO HD is 100 mbs, which is 100 mega BITS per second… 8 bits to a byte and you’re looking at only 12.5 mega BYTES per second (MBs), which is well within the range of very nearly all HDD’s on the market these days. And that’s only for the full rez/frame rate of 720p/60 or 1080i/60.

Also, as for the tape drive, Jan (from Panasonic) and many others have commented both here and at DVINFO.net, that the tape materials and heads required to read/record DVCPRO 50 and HD are both too expensive and too large to write to Mini DV tape in a cam this size. In fact, I think I’ve seen it that the 16 pairs of heads required to write DVCPRO HD to tape are around $6K cost for Panasonic…

Kevin Dooley
Director of Video Services
Imago Dei Media Group, Inc.

[Deleted User]

Hi Chris: Jan C., the Panasonic product manager has said repeatedly here & elsewhere the new cam won’t include a DVCPRO-50 or DVCPRO-100-HD capable tape transport. Do you need something more definitive than that?

As Jan has said and others have confirmed, DVCPRO-50 & -100 tape transports are _big_ and _expensive_. The new cam is neither. So, the tape transport in the new cam is for 25 megabits/sec DV only. Period.

As for your questions concerning harddrives playing/recording the above compressed video formats: Yes, most modern 3.5″ and smaller harddrives can easily handle the maximum 100 megabits/sec (plus overhead) datarate required. Note: “Megabits”, not “megabytes.” Big difference, yes?

As for the iPod reports, I believe it was BlackMagic Decklink who did a technology demo using an iPod for compressed HD playback, and in general the BM Decklink folks are pretty reliable. They’ve forgotten more about HD than most people know, so I think you can trust them when they say this sort of thing is generally possible — even if it was partly a geek/publicity stunt.

For most production work there will likely be a variety of rugged portable HDDs available for use with the new cam once it ships later this year.

All the best,

– Peter

Just a friendly reminder to all: Please consider filling-in your COW user profile information so we have a better idea who you are, where you’re from, and so forth. It’s the friendly thing to do. Thanks!

[Jeremiah Black]

Chris,

Yeah, Kevin just posted a great response, but that’s where I think the confusion is arising from. 100 mega bytes (mb/sec – small b) as opposed to 100 mega bytes (mB/sec – capital B).

As far as 25 mb/sec being the “limit” on mini dv tapes- it’s a function of mini dv tapes. You could run the tape at twice the speed to get a DVCPRO50 signal, or at 4 times the speed to get a DVCPRO HD signal, but dv tape is too flimsy to run at four times speed and be reliable.

And, yes, I had posted earlier that it cost $800 per pair of HD record tape heads (Panasonic’s cost to build- not even the selling price), and there’s 8 pairs ($6400). So, a tape transport that can record HD would be really expensive, and could only take HD tape. There’s a camera that already has this, and it’s called the Varicam. And it’s pretty expensive comapred to the P2 camera. Even with the cost of P2 cards.

One thing, however, that’s interesting to think about is that the mini-DV that the P2 camera does record to tape does originate off an HD chip, so it may look better than most mini-dv out there. If it’s a downconveted HD signal, I mean.

jeremiah black
dual 2 gig G5
2.5 gigs of RAM
Decklink Extreme capture card

[Blub06]

Thanks to all of you for cleared it all up for me. My world is a megabytes world not a megabits world, I don

[Toke]

There is one tweak that is possible, if these rumours about slo-mo capture to tape are real.
You could rec half an hour of 480p60/576p50 to miniDV tape and speed it up in the edit.

[Jeremiah Black]

The slow motion will only be available for the 720p mode, I believe, and thus will only go to P2 cards, not to tape. NTSC mini dv tape must have 29.97 frames on it.

jeremiah black
dual 2 gig G5
2.5 gigs of RAM
Decklink Extreme capture card

[Toke]

You record 29.97fps to tape from 720p59.94 material in p2 card.
Copying & downconverting & slowing is done “realtime” by the speed of tape.
So making this half an hour of “480p59.94” material will take a whole hour.
If its possible anyway.
Get it?

[Jeremiah Black]

Interesting idea. But, I believe, when the signal is “downconverted” it’s not downconverted in a traditional sense from one codec to another. It’s merely squeezing an HD image off the chips down to an SD size. Frame rate, which is a function of a specific codec, hasn’t entered into yet.
Get it?

jeremiah black
dual 2 gig G5
2.5 gigs of RAM
Decklink Extreme capture card