View Full Version : Cheap flash memory.


Bruce Quayle
December 6th, 2005, 03:44 PM
How come flash memory is available relatively cheaply when connected to a USB port yet the P2 is so hugely expensive? Here is an interesting site:
http://www.911usb.net/products_new.php?osCsid=af420b6843eb9bad674090112df2252f
4 Gigs is costing only $298!
I know this doesn't fit the P2 slot, but what about someone out there making an adapter?
Bruce

Barry Green
December 6th, 2005, 05:50 PM
How come flash memory is available relatively cheaply when connected to a USB port yet the P2 is so hugely expensive? Here is an interesting site:
http://www.911usb.net/products_new.php?osCsid=af420b6843eb9bad674090112df2252f
4 Gigs is costing only $298!
I know this doesn't fit the P2 slot, but what about someone out there making an adapter?
Bruce
Cheap flash memory has nowhere near the speed necessary. Only the Sandisk Extreme III is fast enough to store a 100-megabit DVCPRO-HD stream, and it's about the same price, per gig, as a P2 card is (retail MSRP to retail MSRP). And as far as "hugely expensive", keep in mind that "real" p2 pricing hasn't been released yet. We'll probably find out what the REAL prices are tomorrow at the DV Expo press conference.

Cheap memory is cheaper, but it's of no use because it's not fast enough. Even "high speed" cards aren't fast enough; they max out at 9 or 10 megabytes per second, and DVCPRO-HD needs around 13 megabytes per second.

Then you have to factor in that a P2 card is six times faster than realtime when transferring files. It's capable of 640 megabits per second (around 80 megabytes per second), so transferring files in the edit suite will be dramatically faster off a P2 card than it would be off of even the fastest fastest fastest compactflash or SD card.

Jeff Kilgroe
December 7th, 2005, 10:02 AM
Cheap flash memory has nowhere near the speed necessary. Only the Sandisk Extreme III is fast enough to store a 100-megabit DVCPRO-HD stream, and it's about the same price, per gig, as a P2 card is (retail MSRP to retail MSRP). And as far as "hugely expensive", keep in mind that "real" p2 pricing hasn't been released yet. We'll probably find out what the REAL prices are tomorrow at the DV Expo press conference.

Barry, I know you're "the source" here, but I have to call you on this one. The current crop of 4GB P2 cards from Panny contain 133X SD chips. 1GB @ 133X chips are available everywhere (literally) as it is the industry standard speed for mid to upper quality SD in that capacity. 133X chips are capable of a max throughput of 14.9 MB/sec, with most real-world benchmarks showing about 12MB/sec. Using an interleaved memory controller and accessing these chips in a quad-channel arrangement should yield about 44 to 48 MB/sec throughput for the P2 device that contains them. 44MB/sec is 352 Megabits/sec or 3.5X the speed needed to record DVCPROHD.

Even lower speed 120X SD chips should still provide more than enough bandwidth for DVCPROHD. Each SD chip in a P2 card must be able to sustain a write speed of 3.125MB/sec (12.5Mbps) in order to accommodate DVCPROHD. The P2 implementation uses 4 separate SD chips on a 32bit, interleaved, quad-channel controller. Thus it's the combined bandwidth of all the SD memory in the card and none of the individual chips need to be capable of the full bandwidth needed.

Then you have to factor in that a P2 card is six times faster than realtime when transferring files. It's capable of 640 megabits per second (around 80 megabytes per second), so transferring files in the edit suite will be dramatically faster off a P2 card than it would be off of even the fastest fastest fastest compactflash or SD card.

Actually P2 is faster than that! The P2 interface is capable of about 1056Megabits/sec. It is a 32bit Cardbus PCMCIA II standard card at 33MHz, which yields a maximum rate of 132MBytes/sec (see pcmcia.org for complete info). It would require 180X SD memory, which *IS* available in 2GB chip yields to create a P2 card with the 640Mbps ability they have claimed. Most likely Panny claimed the 640Mbps rate because it coincided with the fastest commonly available SD chip speed at the time of their announcement and at the time of their first prototype runs of 8GB P2 cards. I don't know if they actually used any memory at that speed or not, but I'm guessing the 640Mbps speed is something the marketing guys plucked out of a technical brief or whitepaper that outlined potential SD tech to be used for upcoming P2 card models.

Barry Green
December 7th, 2005, 09:29 PM
Last time I looked at SD cards, Sandisk's Ultra II was advertised at a sustained write speed of 9 or 10 megabytes per second, and only the Extreme III was listed with a higher speed, that being a sustained 20 megabytes per second. If there are other, faster options out there, that's excellent!

P2 card pricing has fallen quite a bit, too. Whereas the last time a price was quoted for a 4gb card it was $1750, the new pricing is $650. And that's retail; "street" price still remains to be seen. But seeing as a Sandisk Extreme III 4gb CompactFlash card carries a retail price of $599, and a 4gb P2 card is 4x as fast and costs $50 more, I'd say the pricing looks reasonable for what it is, right?

Jeff Kilgroe
December 7th, 2005, 11:59 PM
Last time I looked at SD cards, Sandisk's Ultra II was advertised at a sustained write speed of 9 or 10 megabytes per second, and only the Extreme III was listed with a higher speed, that being a sustained 20 megabytes per second. If there are other, faster options out there, that's excellent!

Yeah, the Extreme III is insanely fast. It's using the new Samsung SD product and they should be able to cut that price by 60% or more within the next 4 months or so and Samsung is also claiming SD chip capacities will reach 8GB by the middle of 2006. So we should se 32GB (and maybe larger) P2 cards late next year.

My whole point with the previous post was that even with this super fast SD memory out now, it's not necessary for P2 to work and accommodate DVCPRO100. A single Sandisk Extreme III is more than capable of the full speed required (20MBytes = 160Mbps). But like I said, P2 doesn't work that way... It's 4 individual SD chips in a quad-channel array, much like a RAID0 stripe set of hard drives. Each SD card only needs to sustain a 3.125MByte/sec write speed to accommodate DVCPRO at 100Mbps. Most of the generic SD chips you can buy for less than $40 per 1GB will meet that criteria -- although, zero-defect is a whole other matter and that will cause the price to go up a bit once again.

P2 card pricing has fallen quite a bit, too. Whereas the last time a price was quoted for a 4gb card it was $1750, the new pricing is $650. And that's retail; "street" price still remains to be seen. But seeing as a Sandisk Extreme III 4gb CompactFlash card carries a retail price of $599, and a 4gb P2 card is 4x as fast and costs $50 more, I'd say the pricing looks reasonable for what it is, right?

As you have probably noticed, I've been a critic of P2 pricing here in the past. But these new prices are very encouraging. A high quality, 1GB SD chip with a zero-defect rating at 6MB/sec goes for about $125 on the street these days. I've seen them cheaper, but from most brick and mortar vendors that don't price gouge, that's about what to expect. Retail is closer to $200. So figuring 4 of those chips in a P2 package from a vendor like Panasonic, $650 retail doesn't seem too bad at all. Street price will probably be somewhere in the $575 range once the market settles a bit and prices will plummet once other memory suppliers ship P2 products.

Kaspar Stromme
December 8th, 2005, 12:01 PM
One thought: I can see the need for P2 when recording DVCPROHD at 100Mbps, but what about DVCPRO50 and 25? Why do they need P2-type speed?

And taking that further, why not have a DVCPRO-HD 50Mbps standard? Still twice the data of HDV, at 720p it would be pretty darn good. And also not need as fast card..

(sorry if this has been suggested before)

Jeff Kilgroe
December 8th, 2005, 04:12 PM
One thought: I can see the need for P2 when recording DVCPROHD at 100Mbps, but what about DVCPRO50 and 25? Why do they need P2-type speed?

P2 is simply a storage format that they chose that more than meets the requirements and if it is well accepted, should provide compatibility into the future, far beyond the current DVCPRO standards. Currently, there are very few solid state memory devices that can provide the necessary 100Mbps sustained bandwidth needed for DVCPRO, but using these commonplace components (which are too slow on their own) in tandem, the ability to far surpass the minimum is there. They don't *need* P2 speed, but it sure is easy to produce and a logical progression of the tech that's available today.

A better way to put it is that a single SD chip on it's own can't cope with DVCPRO100 and would probably struggle with 50Mbps in most cases. But interleave 4 of them together, you get 4X the capacity and nearly 4X the speed with a nearly linear progression in price.

And taking that further, why not have a DVCPRO-HD 50Mbps standard? Still twice the data of HDV, at 720p it would be pretty darn good. And also not need as fast card..

Your wish is granted... Sort-of.

720p @ 24fps only requires a 40Mbps data stream and does not use the full 100Mbps bandwidth. 720p @ 30fps requires 50Mbps. Recording to P2 allows only active frames to be stored, so your frame rate in 720p will have some degree of effect on the data rate of what you're recording. You can recorde about 13.5 minutes of 720p24 on a 4GB P2 card. If you record 720p @ the 60fps max, it will require the full 100Mbps of the DVCPROHD format. 1080 line mode in DVCPROHD is *always* recorded at 1080i60 @ 100Mbps. It supports 24p, 24pA and 30p the same way the DVX100 does by internally handling a true 24p stream, but encoding it to fit within the 1080i format standard. This is a limitation of the DVCPROHD standard, not the camera as Panasonic didn't want to break compatibility with existing DVCPROHD systems. Besides, as we have all seen with the DVX100, this method of delivering 24 or 30 progressive frames/sec over an interlaced standard works beautifully.