Digital audio recording has many advantages over old analog cassette equipment. However the downside to digital recording is that there are no simple solutions for preserving your audio files. Every choice you make will force other decisions down the road, especially if you are interested in preserving your recordings over the long term.
The Vermont Folklife Center believes that the value of digital recording, which to us has much to do with the simplicity of editing digital audio files so that multi-media projects can be more easily produced from them, and the lower initial expense to acquire hardware and software to assist in the transcription of digital audio files, outweighs the complications of providing access to and securely storing them.
This document provides a very brief introduction to the equipment we recommend using and methods you can use that will help to preserve your digital recordings over the long term.
Currently we recommend using the following audio recorder:
Although the Marantz PMD661 has limitations, for most interview recording applications it is the best available option in its price range. We recommend that anyone considering purchasing the unit search out quality product reviews to be sure the PMD661 is a good match for your application. A useful review can be found at the following location:
The Marantz PMD661 is a less expensive professional unit that meets most of our requirements. Most importantly the Marantz PMD661 can be used to create standard, uncompressed audio files in the WAV file format.
WAV files are large, uncompressed, high-quality, standard digital audio files. Since WAV files are uncompressed they have better audio fidelity than recordings made using many compressed formats. In addition, since the WAV format is a digital audio standard, any audio editing or playback program should be able to open them. This is an important consideration to be aware of when you want to preserve your recordings over the long term.
The Marantz PMD661 has no moving parts. When you record, it creates and stores the digital audio recording on a removable Secure Digital (SD) memory card identical to the kind used in many digital cameras. SD cards can be reused over and over again, so in the long run they can prove quite economical.
The quality of digital audio recordings is affected by a number of factors. Two factors that have the greatest impact on the quality of a digital audio recording are the bit depth and sampling rate of the digital audio file. In the interest of space, I will not go into a longer explanation of exactly what these terms mean. However, for the sake of creating recordings that balance quality with file size, we recommend creating files that are 16 bit, with a sampling rate of 44.1kHz in mono. Using a 1 gigabyte Secure Digital (SD) card in the Marantz PMD661 will allow you to record approximately 3 hours of digital audio at these quality settings before you will need to upload your audio and erase the card.
Storing Your Recordings
Since the Marantz PMD661 creates and stores audio files on a reusable medium, in order to begin the process of saving and editing your recordings you need to transfer the audio files from the machine to a computer. Storing digital audio files for preservation purposes is a somewhat complex matter, and there are no simple solutions.
The preservation of digital information (which is what your digital recordings are) hinges on three factors
- Interoperability - creating digital files in standard, non-proprietary formats that will be supported over time.
- Redundancy – storing files in more than one place and creating multiple back ups on secure media.
- Migration – shifting files to new media before the old media degrade and/or become obsolete, and shifting files to new standard file formats before the old formats are no longer supported.
- Documentation – generating, storing and tracking metadata: information about the nature, structure and content of your digital files.
Since your recording will be created and saved as WAV files, you are already part of the way there. Unfortunately, this first step in the digital preservation formula is the easy part.
We recommend taking a multi-layered approach to the storage of digital audio files. Since most of us probably do not have a RAID-enabled, data tape backed up, file storage server in our living rooms (and probably wouldn't know to how run it even if we did!), below are some reasonable, lower-cost, approaches to digital file storage and preservation.
- Save your audio files on multiple external hard disc drives. If you happen to have access to a professionally managed file storage server through your school or work, ask the IT department if they will allow you to have space on their machines as well.
- Create multiple backups of your audio files on optical media, either CD-ROM or DVD-ROM discs. Use high-quality discs such as those produced by Taiyo Yuden or MAM-A.
- Keep your storage materials in more than one physical location. Store CD-R or DVD-R discs in a cool, dry place away from direct sunlight.
- Check your files and media regularly. Transfer your files to new media if you suspect any problems.
- When the time comes: Migrate, Migrate, Migrate.
CD-DA vs CD-ROM
Audio files can be saved on standard blank CD-Rs in two ways: So that the audio file stored on the CD disc can be played back in an audio CD player—the CD-DA format—or simply as an audio file in the same way you might store digital images or document files to a CD—the CD-ROM format. CD-ROM discs cannot be played back in audio CD players like the ones in cars or home stereo systems. To access the audio files on them you will need to use a CD-ROM dive on a PC and the audio editing and playback software on your computer. However audio files on CD-ROM discs are somewhat more secure and much easier to directly access than those on CD-DA discs.
This is not to say that CD-DA discs are bad. CD-DA discs are great for access copies and sharing the edited material created by you. For more information on creating CD-DA discs for access, please see :: here
A Short Note on Recommended Brands of Blank Optical Media.
There is no such thing as an “archival” CD-R. There are, however, brands of CD and DVD discs that archivists prefer. CDs and DVDs manufactured by the Mitsui company and sold under the MAM-A brand and those manufactured by Taiyo Yuden tend to be most favored by archivists.
If at all possible, we recommend saving at least one copy of each interview recording on two different brands of media, for example on both a MAM-A Standard Gold or Archival Gold CD-R and a Taiyo Yuden silver CD-R. Since MAM-A and Taiyo Yuden discs are difficult to find in stores, the best way to locate them and compare prices is by searching the web for retailers that sell MAM-A and Taiyo Yuden.
© 2005-2010 The Vermont Folklife Center