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Re: Slightly OT- reel-stream for HVX-200?

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Peter DeCrescenzo
Re: Slightly OT- reel-stream for HVX-200?
on May 8, 2005 at 8:25:56 pm

That's right: A proper implementation of USB-2 or Firewire 400 can handle uncompressed SD video, which is what the ReelStream folks are apparently doing with their project for the DVX100.

Their modification for the DVX100 enables them to acquire uncompressed SD video data (actually a few pixels higher res than SD) directly off the cam's CCDs and stream it out to a fast portable USB-2 hard drive or computer. Once the data is on the computer, their software app can uprez it to HD or convert it to a variety of SD formats.

Doing something similar with the HVX200 would require a _much_ faster hardware interface between the modified cam and the external storage/computer. I believe uncompressed 10-bit 720p 24 fps video is around 150 megabytes/sec (that's megaBYTES/sec); and 10-bit 1080 resolution requires closer to 200 megabytes/sec, and 1080 4:4:4 is more than that. Needless to say, USB-2, FW-400 and FW-800 interfaces can't handle these rates.

I believe an interfaces such as gigabit Ethernet and HD-SDI can handle 10-bit 4:2:2 HD, but 10-bit 4:4:4 HD requires dual-HD-SDI.

Further, to the best of knowledge AJA & BlackMagic/Decklink specify that a computer intended to handle any form of uncompressed HD video must have PCI-X as the minimum system bus. So laptops and many desktops are out of the question for uncompressed HD aquisition, capture and so forth.

There's a good reason why acquisition codecs like DCVPRO-HD and HDCAM were invented: They do a surprisingly good job, and can run on relatively portable, inexpensive, battery-operable hardware.

Once an "inexpensive" version of an all-solidstate recording device like the CineRAM becomes available, then things may start to get interesting indeed. But I suspect it'll be awhile -- until prices come w-a-y down -- before most shooters will consider owning such a device for recording uncompressed HD.

All the best,

- Peter

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