There are an infinite number of processes that can affect the human perception of sound. For example, the live sound of an orchestra is dependent upon the venue, the audience and the local ambience.
So what is the aim of a restoration engineer? The archival viewpoint suggests that such an engineer should present the listener with the most authentic reproduction of the original sound that can be obtained. But what about the creative influence of the recording engineer?
With modern recordings, the ensemble sound often exists only on the recording medium, and many parts of it have probably never been through a microphone. Therefore the commercially minded engineer may, in contrast, attempt to generate a new recording more appropriate to its intended use. This use could be, for example, to please the public palate, or to represent accurately the sound of an era. Every restoration has its own criteria.
The algorithm designer is responsible for creating the facilities by which the restoration engineer generates new recordings from old. He or she does this by developing and implementing algorithms which remove unwanted sounds and/or effects present on the old recording.
CEDAR AUDIO & iZotope RX advanced software provides a powerful set of restoration tools flexible enough to be used as the restoration engineer sees fit. However, it is always my policy that the human ear should always be the final arbiter of sound quality; judgements based upon signal processing techniques are secondary considerations.
There are times when audio requires more than just simply enhancing ...
An old analogue reel of tape, for example, or an LP album of which only a few vinyl copies exist; vintage material from 78's or even earlier formats.
Shaw Sounds are superbly equipped to deal with such projects - we have sophisticated restoration software available including Cedar, iZotope and Steinberg Technology" with de-crackle, de-hiss, de-click and de-buzz algorithms.
We also have a full complement of vintage equipment for playback through 24-bit A to D converters for best transfer quality - this has made us a respected and successful facility.
We deal with all kinds of music projects from Classical to Popular, Choral to Jazz including spoken word and delicate historical archive material.
We believe restoration requires great sensitivity on the part of the engineer - just because we can remove the hiss in a recording it doesn't mean we should , the recording could loose "life" or "air" as a result.
Many restoration software programmes today can provide radical processing of the source signal like hiss, de-clicking & de-crackling - we at Shaw Sounds are careful not to damage the original material by over use.
An intimate knowledge of our equipment and it's capabilities allows us to avoid the pitfalls of the process. An experienced engineer develops his own strategies and methods - tricks of the trade, if you like - along with an understanding of the needs of the material, help us achieve the best possible result.
These are usually the most common requests
Removing clicks, pops and groove noise from records ( LPs, 45s, & 78s ).
Reducing broadband hiss from records, old reel-to-reel tapes and cassettes.
Re-pitching and correcting tone inconsistencies.
Making audio programmes louder, or balancing varied volumes levels.
Converting mono recordings to stereo with spatial enhancement technology.
Remastering records to CD.
Isolating particular unwanted sounds from live recordings.
Editing and space adjustment between programme material.
Compiling and restoring different source tracks to produce a final master CD.
Conversion of analog and digital material to different file formats.
The CEDAR (Computer-enhanced Digital Audio Restoration) system is a commercial system for restoration of degraded recordings of all types. The system allows for real-time click, crackle, hiss, buzz and distortion removal in mono and stereo. The authors were both founding members of the company and are involved in strategic research and consultancy for the company. It should be emphasised that the algorithms and methods employed by CEDAR are not detailed for reasons of commercial secrecy.