Flash vs. SxS: what's the difference?
 

These new units are using flash cards as opposed to the SxS cards of the EX1. WHat's the difference between them? Are they both a kind of flash card? I'm in the dark...

They both use flash memory.

Compact Flash is a standard format that is very commonly available.

You should be seeing Expresscard based flash drives. SxS is just that and Expresscard based flash drive.

The SxS are high performance- according to a Sony engineer they need to sustain 200Mbps for the EX1's overcranking modes- which in fact led Sony to spec out 400Mbps as the standard. So... while you may be able to get Flash Expresscards in the EX1 they won't work properly- if at all- unless they meet the SxS performance standards.

The SxS standard is 800Mbs, not 400, see the original press release: http://www.sandisk.com/Corporate/Pre...e.aspx?ID=3770 (End of paragraph below the picture of a card.)

Regarding the overcranking performance, talk of higher than 35Mbs bitrates would make sense if the camera is running at 60fps speed, but laying it down at a 60/24 times the standard HD-XDCAM rate, in a way that normal playback would see a standard 24fps 35Mbs peak stream. (Very clever if true.)

But that means a peak bitrate of 87.5Mbs, which is well within the capability of fairly standard CF like Extreme III (160Mbs.) let alone the higher grades such as Red requires (Sandisk Ducati is rated at 360Mbs).

I believe the reason the EX uses SxS, not CF, is less to do with technical matters than to make it compatible with future SxS products and developments. If future ExpessCards suitable for the EX come out with the price/performance of Extreme III that will be very good news indeed. They may not download as quickly, but on a budget that may be a small price to pay, and the option for high cost/performance remains.

That option of choosing your own price/performance would give it a substantial advantage here over P2, which forces a user into the high end with no choice.

seems the CF recorder comimg with the Z7 will be compatible with the Z1.

I originally wrote this post over in the "EX1 shortages" thread where its a bit off topic.

http://dvinfo.net/conf/showthread.php?t=107959

Here is the original post:
http://www.dvinfo.net/conf/showpost....3&postcount=24

*******
Before I even go on, take this post with a grain of salt.

I haven't used these cameras in serious production, only at a trade show- and we all know what that can be like.

I am repeating what I was told by two Sony SSE's on separate occasions.

I didn't get to test or verify this stuff.

800Mbps is the spec for reading. SxS must read at that speed. I can't say for certain if that is a peak or sustained specification. My talk didn't get that specific. I think its a sustained read speed though.

Why do I think that?

The sustained write speed is around 330Mbps. I'll be back to this.

Well, its Sony, and we know their format track record. This thing is too good.

So how could they complicate this?

I suppose the could allow "tiers" of certification. The notion being that the tiers correspond to the various grades of tape.

So we may see SxS that can only be used for recording SP mode. Maybe any expresscard 34 flash drive would be allowed to work at this level.

We may see SxS that can record HQ mode.

We may see "Master Grade" SxS that can support overcranking.

For the record, I don't think we are going to any inanity of that sort.

I think there will be certified SxS that will support all the camera features- and that's it officially.

I'm coming back to this.

Take a look at the specs for Sony's SR Motion system. One SSE specifically mentioned SR Motion for comparison. Of course that is a very high end product.

I think that the XDCAM EX series is offering a low end version of those capabilities.

If I am recording 60p for 1 second I get 60 frames in 35Mbits of data.

By comparison, if I am overcranking to 60p for 24p playback for 1 second I'll get 60 frames in 83Mbits of data. Exactly as if I'd recorded 24p for 2.5 seconds.

See the difference?

So, why specify over 300Mbps to manage 83Mbps?

FAT32 fragmentation.

With an "XDCAM" & "Cinealta" badged product Sony wants to assure the ability to record so long as there is space. Even on a highly fragmented SxS volume they need to sustain 83Mbps

So, their systems engineers estimated that they needed 160Mbps sustained write to get the job done on fragmented volumes. They doubled that for the specification to provide assurance that the media could meet the requirements.

So.. this would be an absolutely amazing feature if its true. Almost too good to be true.

Why do I lend it credence? Two SSE's told me the same story with lots of details that match up. Could they have been having me on? Sure. Could they have been misinformed by some third party? Sure.

I am going to believe it tentatively. I am trusting like that.

I am eager for someone to check this out specifically.

So back to non certified Expresscard flash drives. (I expect that only drives certified to work with XDCAM EX will be badged SxS)

There may be some ability to work with uncertified Expresscard 34 flash drives. Sony may throw us a bone on this because they want SxS to succeed wildly. They don't want to beat P2, they want to crush it so shamefully its mom will disown it.

It may not be supported, but lets face it- if we wipe our cards every time we take them out of the camera, fragmentation won't be an issue.

In that case even a fairly low spec card should work well enough for almost every camera function. The theory is that a card that can sustain a mere 200Mbps with no fragmentation should work perfectly.

If theory proves not to jive with reality and it doesn't work, or if it doesn't work well, well Sony warned you.

No, it won't be. Its a special item that hooks directly to the Z7 and S270 with a proprietary interface.

Here are some pictures I took at GV Expo.

But the Sony brochure for the camera and CF card unit says:

"The Memory Recording Unit can be used as an external recording
unit, just like the HVR-DR60, by attaching the supplied cradle that
has an i.LINK connector, battery attachment and DC power
input. "

It would seem to me that you might be able to connect it to the i-link IO of any DV or HDV camcorder. Just a guess on my part.

Cheers
David

My first question would be if the CF option has the same amout of lag between Camera and VTR mode, like the EX-1 has. That's a real concern for me. If it takes over 10 seconds for the SxS chip to load in VTR mode, I wonder if this camera's CF option will be faster or slower in comparison.

That's not correct Alexander, the CF recorder will work with other Sony HDV devices that have a firewire port, just like the HVRDR60 does.

The CF unit comes with a cradle you can dock it into that gives you a firewire connection and a slot to power it using an 'L' series battery. I think the cradle even has a cold shoe on the bottom so that you can attach it to the back of a camcorder.

To me the question isn't so much whether the camera uses SxS or Compact Flash, but whether or not the memory choice is open or not.

The Z7 will use any Compact flash that has a minimum speed of 133x. The EX1 will only use Sony branded SxS cards which are EXTREMELY expensive.

In order to use the EX1 on the kind of shoots I typically do, I would need enough storage for somewhere between three and four hours. With the Z7 that amounts to several hundred dollars worth of cards. With the EX1, it amounts to several thousand dollars worth of cards. There are some SxS cards that are quite inexpensive and would likely work just fine if they were allowed. This has nothing to do with anything other than control and greed.

http://www.ecost.com/Detail.aspx?edp=38347202
http://www.ecost.com/Detail.aspx?edp=38347211
http://www.ecost.com/Detail.aspx?edp=38347211

Yes the EX1 will probably gradually loosen these restrictions, but that will do little to help me over the next year and a half to two years.

I don't know what part you were objecting to, but I really did take those pictures at GV Expo! :)

Seriously, I was only reporting IN NOVEMBER what Sony SSE's told me. It was early pre-release information. In fact I think that was the first day or two they showed the camera in public at all. So please- don't shoot the messenger!

I specifically asked about this, and even lamented that it was "too bad." A cradle is a good idea.

At that time there was no evidence of a cradle- it had to be attached directly to the camera at the time. I was also told that the only way to get one of these units was to purchase a camera that included one. Something else I lamented.

As far as the state of affairs now, I don't know.

Actually Sandisk will be making SxS cards. It is supposed to be an "open" standard. In fact- there isn't really anything that separates SxS from any well engineered Expresscard flash disk.

I expect the camera to work with any Expresscard that is fast enough- its just that only SxS cards are fast enough right now. By a long shot.

One reason is that Expresscard slots offer two interfaces. There is a 1x PCI Express interface, and a separate USB 2.0 interface.

A lot of third party Expresscard flash disks are using the USB interfaces because its easy and cheap. It also assures that they can't begin to sustain write speeds sufficient for the EX1.

I expect that to change.

Oh this timeline may be pessimistic- but I certainly concede your point.

Oh and by the way while 133x cards should work in these cameras, I advise you to purchase and use 300x media. (Which is still far cheaper than SxS currently.)

The reasoning I use is the same Sony engineers used when setting SxS performance at a sustained 400Mbps write.

The throughput of a 133x card should theoretically be about five times faster than the mpeg2 stream from an HDV should require. Real world tests show that these cards will have a much lower real world transfer rate, yet should still be fast enough by a comfortable margin, even if it's less than 2x the speed of the HDV stream.

I plan on using 133x cards to see if they work OK (which I expect they will), but reformatting them each time that I use them since a little fragmentation could very likely slow a 133x card down to the point where you could possibly have problems.

Over time, I expect that faster cards will become quite common.

The following link is about a year old and was written when 133x was as fast a compact flash as was available.

Notice how little extra there is for an HDV data stream on some of the cards. This would worry me more if I wasn't already used to dealing with media that had no extra headroom (tape).

http://www.dpreview.com/news/0601/06...r133xcards.asp

Headroom on tape is meaningless. You shouldn't think of tape in those terms.

Tape moves at it rated speed and that's it. Anything different- both faster and slower- is just broken. You can't use such a "variable speed" tape.

The same thing that headroom accomplishes in bandwidth applications is accomplished on tape with error correction and redundant coding. (Well for digital tape.)

On the other hand- I think you can record to CF and tape simultaneously on the Z7 and S270.

That should alleviate any risks while testing any given media for performance.