Review: Prism Sound Verifile

Verifile might be a completely free addition to the latest software and firmware update for all Prism Sound USB interfaces, but it’s an incredibly valuable tool to incorporate into your workflow, writes Alistair McGhee..
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Prism Sound Verifile

Prism Sound Verifile

There are many things we might miss about analogue recording, like editing with razor blades for example, the physicality of tape and working with massive pieces of Swiss mechanical engineering. Studer A80 how we miss you. But what we miss most of all is off tape monitoring. 

By the simple expediency of putting the record head before the replay head in the tape path, you could listen off tape and be pretty, very, almost certainly sure that you had a serviceable recording. Digital has come bearing many gifts but off tape monitoring (with the notable exception of some professional tape based formats) is not one of them. So how can we be sure that the digital file we have written is intact? Well we can rely on the tried and tested method, which is basically assuming that as most of our recordings are ok then this one is probably ok too. 

When you write that out it doesn't seem like such a good idea, which is why Prismsound have come up with Verifile. Verifile is a means of alerting you to errors in your recorded files that has been four years in development and is now available free and gratis with every Prismsound USB interface. So how does it work? Well at the 'how do I drive a car level', it is simplicity itself. 

You open the control panel of your PrsimSound USB device and hit the Verifile button, it turns green and hey presto we have verifile engaged. Now every recording you make over your USB connection to the computer via the analogue inputs to your interface will have Verifile information encoded into the dither of the audio file. The integrity of this invisible, indeed inaudible information is then able to be queried by a Prismsound Verifile app in a matter of seconds. 

So within a minute of finishing your recording you will be able to say with confidence that the performance is 'in the can.' The extra Verifile information is hidden in the random dither applied to the digital output of the interface. But what do we mean by 'in the can'? Well we can now be 99.9999% sure that our recording is bit perfect, in fact much more confident than that but I've run out of my quota of '9's for this month. 

You can check your file in real time during playback and you can check your signal path E to E in and out of the Prismsound converter for Verifile compliance. But how at risk are we? Well we don't know until we have a reliable way of testing our systems. That is actually one of the benefits of Verifile - if your recording workflow is problem free - then you will have visual confirmation of that good news.

Last week I took a Prismsound Titan with Verifile out on a gig - a simple three-piece band with six mics. The job was to record and play back - very straightforward except when we came to playback - we experienced some tweeter shredding noise that signified something seriously wrong. Ironically on the first job I have ever done with Verifile - talk about timing. 

As it turns out a misbehaving DAC was the culprit and the audio files were fine. Back at the ranch I ran some simple recording tests on my office PC and what do you know, on the third file I recorded I saw my very first Verifile error. Now Verifile is not in the business of attributing seriousness to error conditions - though obviously if your file is riddled with errors it is more likely to be audibly damaged than be the single sample problem I experienced in my sixteen-second-test file. 

In fact the error was inaudible and not a problem, however if it was a never to repeated record session - I would have the warning I needed to at least cover that section of the file with a retake. Now, the Verifile signal itself is fragile - any changes you make to the original rushes will destroy the Verifile information. Even a small change in the level of the file, or even re-saving it with a dither option enabled will be enough to ‘deVerifile’ your file. 

Probably all of us have experienced system update misery - a Windows update, a new MAC OS release or just a new driver can reduce our computer-based recorders to junk. In fact we may well have existing problems recording bit perfect audio that we don't even know about. Verifile makes that ignorance a thing of the past, it makes quantifiable the state of our recordings and by extension our recorders. It's a milestone for those who take their recordings and recording systems seriously - it is digital delivering in a significant way on that original promise - 'Perfect Sound forever’. 

RRP: Free 

Key Features:

  • Analyses audio streams for any clicks, pops, drop-outs, errors
  • Doesn't impart anything onto the signal

  •  Can be played back through any normal audio paths and devices

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