Recording and Production in the News

Audio Clicks, Errors And Dropouts Are No Longer A Problem With Prism Sound’s Verifile

This exciting new technology, launched at NAMM 2018, is now incorporated as standard in Prism Sound’s USB range of audio interfaces.

Anaheim, California, USA: January 23rd 2018: UK manufacturer Prism Sound is using the NAMM 2018 platform (North Hall, Booth 16109) to launch Verifile, a radical new technology that allows computer audio streams and recorded files to be quickly checked for a wide range of errors and dropouts, without any compromise in the audio content or any additional metadata.

This exciting innovation is now available on Prism Sound’s range of USB audio interfaces including Lyra, Titan and Atlas. For existing users of these products Verifile will be available, free of charge, in the latest software and firmware download package from the downloads section of the Prism Sound website.

Prism Sound Lyra, Titan and Atlas will run the Verifile technology

The development of Verifile was driven by customer demand for a solution to the issues of reliability that have plagued critical recording projects ever since the adoption of computer recording of audio. Typically, general purpose computers whether MAC PC or other OS, are designed to perform a wide range of simultaneous tasks of which audio recording is but one. Even if the user would like audio recording to be given top priority, the computer's operating system is not designed that way, and (even if optimally configured, which they seldom are) it will, now and again, interrupt audio recording to do something else. This is especially true when dealing with many channels of high resolution audio, perhaps with low latency, which needs a continuous high data throughput. The result is usually a recorded 'dropout' of some kind: anyone who has recorded audio on a computer is familiar with repeated or missed samples or entire sections, random clicks, pops - even channel swapping.

Prism Sound rose to the challenge and spent several years developing this new technology. The Verifile process was invented by Prism Sound in 2014, and has been confidentially testing by many of the world’s leading broadcast, recording, mastering and archival organisations, including Cornell University Library’s Audio-Visual Preservation Lab.

Karl E. Fitzke, project collaborator and Engineer at Cornell University Library’s Audio-Visual Preservation Lab, commented: “Loving Verifile here! It has reliably identified dropped, added and altered samples that I forced into wave files using a hex editor. And as part of our digitization workflow for many months now, it has identified very rare but substantial errors that have ultimately demanded recapture of a tape side. But most of the time an error caught by Verifile has been a single sample impulse that we are often able to confidently pencil out with our audio editor, interpolating from its surrounding samples. If we ever have any doubts, we listen to how the result sounds in comparison with the original tape recording.”

Verifile is a ‘fragile steganographic’ process which embeds derivative data within the dither of the ADC, containing a rolling hash code which allows the audio data to be thoroughly and continuously checked. Recovery of this data from the audio stream or file enables verification that the stream or file contains exactly the audio data that was produced by the ADC at the time of recording. Any incorrect samples, missing or repeated audio segments or any other audio errors in the resulting files can be reliably detected, providing complete confidence that the recorded file is error-free.

Processing of any kind of a Verifile recording such as EQ, level changes, additional re-dithering, sample-rate conversion etc will result in a failure to decode the rolling hash code in the dither and hence indicate that the recording is not an original.

As well as verifying computer ingestion during audio production, Verifile can also be used to guarantee uncorrupted delivery of audio content over any bit-transparent delivery media such as networks or dedicated digital communication links. Verifile can also embed limited additional metadata into the audio stream, such as source and copyright details, timestamps etc.

Audio Clicks And Dropouts Are No Longer A Problem With Prism Sound’s Verifile

Graham Boswell, Prism Sound’s Sales and Marketing Director, says: “As the Verifile process relies only on a modified dither component, it is entirely non-intrusive and invisible to the user and has no impact on audio performance. Verifile recordings can be played through any normal audio paths and devices, or mixed or processed within DAW software just like any other recording.”

Once the original audio has been ingested, the integrity of the recorded files can be checked by an off-line software app that runs much faster than real time or can be monitored in real time by Prism Sound interface controller apps (available for Mac or Windows), or in the SADiE software during playback.

Verifile is suitable for any linear PCM audio at sample rates from 44.1kHz to 192kHz, and word-lengths from 16 to 32 bits. Since the metadata is included within the audio stream that it verifies, files may contain any number of audio channels.

“This new technology is very easy to use – it is now built in to the A/D input channels of your Prism Sound interface.” Graham Boswell adds. “This allows you to check the integrity of recorded files later if you want to. If you do, the app will produce a report for each file that confirms the complete integrity of the file, or else indicates the times and channels of any errors. Whether you check them or not, you can use the recorded files as normal. It is possible to turn it off, but there’s really no need, as the process only modifies the dither that is normally present.”

At NAMM 2018, Prism Sound will also be promoting ASIO Direct Monitoring (ADM), which has now been incorporated into its Titan, Atlas and Lyra audio interfaces and its SADiE workstation software. Designed to significantly improve the end user experience for Prism Sound customers, ADM allows mixers in the interface device to be controlled automatically from Digital Audio Workstation (DAW) software. As a result, producers and musicians recording to a computer workstation with performer foldback can now achieve near zero latency by simply enabling ADM in the software.

Prism Sound’s full range of award-winning audio interfaces and converters will be on show at NAMM, including its flagship ADA-8XR, a multi-channel AD/DA converter that can be configured in numerous ways using plug-in modules to suit a wide variety of applications. Renowned for their exceptional audio quality, Prism Sound products are now the converters and interfaces of choice for many of the world’s top artists, producers, composers, mixing and mastering engineers. They are also the mainstay of many internationally acclaimed audio facilities including Abbey Road, Metropolis Studios, Sony, the BBC, ESPN, the Library of Congress and many others.