The second elephant in the room

[Harry]

Regarding the possibility of using portable hard drives: what are the storage requirements at 1080/24p?

Thanks

Harry

[Ken Hon]

Aloha Jeremiah,

You gave Chris a lot of good information, but I’m not sure the part about tape speeds is exactly corret.

“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”

It is my understanding that the real problem is the DV codec boards, not the tape speed. I believe Panasonic uses the same physical size tape in a bigger cartridge for DVCPro HD and 50. The DV codec is limited by definition to 25 mbps and these boards were ganged together by Panasonic (and JVC) to deliver higher end formats. DVCPro 50 uses 2 codec boards (and 8 heads like you said) and DVCPro 100 uses 4 codec boards and 16 heads. It’s amazing they can get this to write to such thin tape, JVC used full sized cartridges and head assemblies for D9.

Aloha,

Ken

[Toke]

For many years there has been dvcam deck that can read/write with 100Mbps.
Although it has 14 heads, there is no limit in miniDV enclosure for not to do this.

[Ken Hon]

I’ve never heard of that one toke, it’s interesting. What did they make it for?

[Jeremiah Black]

toke,

You wote: “For many years there has been dvcam deck that can read/write with 100Mbps.
Although it has 14 heads, there is no limit in miniDV enclosure for not to do this.”

This statement really doesn’t make any sense since dvcam is 25 mb/sec foramt.

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

[Jeremiah Black]

Ken:

Hello,

Pretty interesting stuff. I’m not too familiar with DVCPRO 50 tapes, but I’ve spoken to Panasonic and they’re the ones who told me that running a mini dv tape at 4 times the speed reliably wasn’t possible based on the flimsiness of those little tapes. Perhaps it isn’t so much the tape, per say, but just the fact that it’s in those little cartriges. But, I’ve used the varicam, and I don’t really think it’s the same tape stock in those oversized cassette enclosures.

Anybody else wanna chime in here?

Hello,

– jeremiah black

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

[Barry Green]

[Harry] “what are the storage requirements at 1080/24p?”

Rounded off, it’s about 1 minute per gigabyte.

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[Harry]

Thanks very much for the info

[Ken Hon]

I’m not too familiar with DVCPRO tapes either, so I don’t know if they have a more robust tape for the big cartridges. Our D9 camera has the same 8 head configuration as the DVCPRO 50 but writes to a big tape cartridge. Anyway, it doesn’t really matter as they aren’t going to stuff a 16 head drum in this little camera anyway. I do hope that the rumors about being able to write directly to a hard drive are true. That would be a good stop gap until some other devices start using hi speed memory cards. Maybe portable HD Movie players could use these instead of a hard drive so you can load movies by swapping cards. They would also work nicely in Palm Pilots etc. We need some app that requires really fast memory cards to drive the price down.

[Toke]

https://www.creativecow.net/forum/read_post.php?postid=111321160685887&forumid=193&highlight=dsr-85