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Saturday, June 21, 2014

Is Your Disc Recorder Dropping Frames With Your SSD ?

I've been using my Ninja Blade to record various flavors or ProRes - 1080p30 and ProRes HQ 1080p30 and was experiancing dropped frames. It was using a recommended SanDisk 256gb SSD. It shouldn't be happening but it was. The SSD was a month or two old, the Blade new. I was shooting 30-60 minutes at a time before dumping the drive and formatting it again in the Blade. However I was only getting good long records in 1080p24. In 30, in HQ I was having skipped frames. Now the Blade is cool in that I never lost complete files, but there where 4 sec breaks. This a real pain when shooting a 1hr talking head presentation. 

So I started thinking what's the problem here ? A first I thought it was the Blade but I had a blessed config and the latest firmware. Bad SSD ? Ok, lets test it. I pulled it from the Ninja case and put it into an external eSATA dock. R/W speeds of 500 something mb/sec read and write. Left that test run for a while, still holding.

My next guess was the solution : I realized the SSD had never been filled up. I had been using 25-35% of its capacity on average. What if the drive controller was doing some test of the data it was writing to verify the storage block as good ? Well it turns out something like this was going on.

What I did was fill up the drive by copying folders of img sequences to it in the eSATA dock. I filled it down to a couple free mb. I then formatted it in the Blade.

I'm now recording ProRes HQ 1080p30 without dropping frames. So it looks like at least some SSD's simply need to be filled up with a large file copy so that all the blocks on the drive are sorted out as good or not.  As an alternative to doing a file copy you could leave your recorder in record provided it continues after a drop in frames like the Atomos units. If yours drops out of record and stays that way the file copy option will be easier. Either way, its just one of those odd things you learn as you go.