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Small External Digital Recorders


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#1 John Sprung

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Posted 30 March 2011 - 02:30 PM

I want to get a comprehensive idea of what's out there, what you've used, how it worked -- things like the AJA KiPro and KiPro Mini, Convergent's NanoFlash and Gemini, Sony's R-1, R-3, R-4, etc. There was another one at Showbiz Expo a couple years ago, but I haven't been able to find it on the web. Have I missed any really good ones?

Also need to know about the availability of the recorders and their media. I know that KiPro Mini's are backordered, and SxS cards are scarce.




Thanks --




-- J.S.
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#2 Phil Rhodes

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Posted 30 March 2011 - 02:49 PM

Cinedeck looked good, but I've never used it. They write to normal SSDs and offer Cineform or uncompressed, although I'm not sure what spec the U/C is.

I used to build them, but I suspect my machinations can no longer compete with the integrated devices with custom ASICs.

P
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#3 Frank Glencairn

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Posted 05 April 2011 - 03:45 PM

There is also a new kid on the block called Cinemartin.
Records lossless on SSD or normal HDD off the shelf.

It´s a kind of super iPad with SDI connectors - a mobile workstation that runs on Windows 7.

I did some writeup: http://frankglencair...essed-recorder/

Frank
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#4 Phil Rhodes

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Posted 05 April 2011 - 04:12 PM

Well, if that's still an OK way to go, perhaps my machinations can compete...
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#5 John Sprung

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Posted 06 April 2011 - 01:14 PM

Thanks for the replies. I just yesterday saw the new Codex at Arri's open house. They have it mounted to the top of the Alexa, and recording Arri Raw. The downside is that it uses a proprietary memory box, and you'll only have two or three with the package. If there's an error in transferring from the box to the backup station, the data will be gone before you find out.






-- J.S.
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#6 Phil Rhodes

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Posted 07 April 2011 - 04:37 AM

Now there's single SSDs of adequate performance to record uncompressed 10-bit 24p RGB, I think that's definitely the way to go.

Potentially-interesting but perhaps slightly offtopic technical analysis follows.

I know from experience that actually formatting video sequences into DPX files is quite a large processing load, if you do it in software, because the byte order on the SDI line is not the same as the byte order in any of DPX's many options - so you end up having to touch every single pixel. This is something that can take a low-power (a few watts) x86 processor uncomfortably close to saturation (where uncomfortably close is more than about 50% utilized in a hard realtime context like video recording). There is therefore a great temptation to treat the disk as a raw block device and dump the contents of the SDI input's frame buffer onto it sequentially, developing your own scheme for storing metadata. This is basically what Codex call a "virtual filesystem", or at least about half of it, where they've also written code to read their proprietary disk layout and dump it out to an external device as a standard format such as DPX or Quicktime.

There are other upsides to the raw-device approach, too - you get access to the absolute speed of the raw device with no overhead for filesystem, you don't consume any CPU time on filesystem or data wrangling stuff, and if done properly you don't have to touch every frame if you want to alter a chunk of metadata after the fact of recording it, which is a problem anyone recording DPX sequences will have. Renumbering a long take, for instance, can be quite time-consuming on an S2 box. On the downside, you have to ensure you've created some sort of reliability scheme to allow for power loss during a take, and some people would also see a proprietary filesystem as a way to lock people into one vendor, especially if they surreptitiously encrypted the data to frustrate reverse-engineering. I take an extremely dim view of this sort of shenanigans; that stuff's for the low end.

The downsides are that the disk is then not readable in any other device without special software (and writing filesystem drivers for windows is a minefield, so this is hard to solve in the general case). A device that does put DPX files onto a standard filesystem avoids this and there is no reason that an SSD "magazine" from such a device should not be readable on any computer with an external SATA port (which can be added to almost all current PCs with an adaptor cable costing a few dollars). This is one of the reasons why I find S2's technical approach unfathomable: they're using proprietary disk packs with a standard format on them, for the worst of both worlds.

The upshot of all this is that in the end, it doesn't matter if Codex's disk packs are proprietary or not - you wouldn't be able to read them on non-Codex gear anyway. You could theoretically read S2 packs on anything capable of reading ext3 disks that had an adequate SATA or SCA interface (depending on which version of the equipment), with a suitably configured adapter cable.

P
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