Magic Lantern Forum

General Discussion => General Chat => Topic started by: nomel on May 08, 2014, 10:41:58 PM

Title: Kickstarter Idea: SD Card array, higher speeds with slower cards for raw video
Post by: nomel on May 08, 2014, 10:41:58 PM
I'm a hardware guy and have been messing around with raw video. I'm thinking it wouldn't be all that or expensive to stick a small FPGA between the SD port and an SD card bank (maybe 4 cards) to allow some redundant and/or parallel speeds for recording with slower cards.

So, basically, the fpga would be connected to a dummy SD card. It would split the data between the sd card ports (depending on the number of cards inserted), reducing the required bandwidth for each card. The split data would be rejoined into files on your computer.

The FPGA alone would be around $30, buffer memory quite a bit less, so I'm thinking no more than $100 for the final product (most likely molded epoxy case).

This wouldn't benefit sd controller limited cameras like the 600D, but it might be useful for other cameras, and allow you to use cheaper high density cards.

This will be for an incredibly niche market, but does this interest anyone?
Title: Re: Kickstarter Idea: SD Card array, higher speeds with slower cards for raw video
Post by: kitor on May 08, 2014, 10:47:23 PM
Still, it's nonsense as all Canon cameras has 20 or 40MB/s hardware limit on SD cards.
What would make sense it raid0 (mirror) array of few MicroSD cards, or in case of redundancy raid10, pluggable into CF socket. In CF card size, 3 MicroSD slots will fit without problems, and two slots on height (giving six total).
Title: Re: Kickstarter Idea: SD Card array, higher speeds with slower cards for raw video
Post by: PressureFM on May 08, 2014, 11:00:09 PM
Do it with CompactFlash ;)
Title: Re: Kickstarter Idea: SD Card array, higher speeds with slower cards for raw video
Post by: g3gg0 on May 09, 2014, 11:33:04 AM
please really consider extending the CF port to do that with CF cards.
usually the CF cards are a bottleneck in these cameras, especially those with higher quality and lifetime.
the camera can achieve a bit higher write rate than the cards can keep up with.

so i think you would have to not only add a FPGA, but also some SDRAM for buffering as the latency could cause trouble.

where are you located at? U.S. i guess?
Title: Re: Kickstarter Idea: SD Card array, higher speeds with slower cards for raw video
Post by: ItsMeLenny on May 09, 2014, 12:12:41 PM
>___< I'm resetting the counter:
0 days since the word "kickstarter" has been mentioned.
Title: Re: Kickstarter Idea: SD Card array, higher speeds with slower cards for raw video
Post by: nomel on May 10, 2014, 12:56:54 AM
Still, it's nonsense as all Canon cameras has 20 or 40MB/s hardware limit on SD cards.
What would make sense it raid0 (mirror striped) array of few MicroSD cards

My crummy SD cards have trouble, especially when I'm out for a while and end up with fragmented cards from deleting...so I could use an SD only implementation. :) But yes, I suppose compact flash does make more sense.


so i think you would have to not only add a FPGA, but also some SDRAM for buffering as the latency could cause trouble.

where are you located at? U.S. i guess?

Yes, of course! I mentioned buffer memory after the FPGA price. Yes, I'm in the US.

I'll see what I can throw together in the next few weeks. I suppose the time to make something like this would be now rather than later, as card prices drop. :)