There are now many locations where we store our digital music files. Their original format - CD's and DVD's, our portable music players, computers at home and perhaps at work, portable hard drives and now Network Attached Storage (NAS) devices are becoming more common in the home.  NAS devices for home users provide storage space and other services without needing a full-fledged PC. This is made possible through an operating system that is integrated in the NAS device. In turn, processing, power and memory requirements are minimal.  NAS devices also come with integrated software that allows you to play your music on other network attached devices - the future of music storage.

File Format

An audio file format is a container format for storing audio data on an electronic device.

There are three major groups of audio file formats:

• Uncompressed audio formats, such as WAV, AIFF and AU;
• formats with lossless compression, such as FLAC, Monkey's Audio (APE), Apple Lossless and lossless Windows Media Audio (WMA).

• formats with lossy compression, such as MP3, Vorbis, Musepack, ATRAC, lossy Windows Media Audio (WMA) and AAC.

Uncompressed audio format

There is one major uncompressed audio format, PCM, which is usually stored as a .wav on Windows or as .aiff on Mac OS. WAV is a flexible file format designed to store more or less any combination of sampling rates or bit-rates. This makes it an adequate file format for storing and archiving an original recording. A lossless compressed format would require more processing for the same time recorded, but would be more efficient in terms of space used. WAV, like any other uncompressed format, encodes all sounds, whether they are complex sounds or absolute silence, with the same number of bits per unit of time. As an example, a file containing a minute of playing by a symphonic orchestra would be the same size as a minute of absolute silence if they were both stored in WAV. If the files were encoded with a lossless compressed audio format, the first file would be marginally smaller, and the second file taking up almost no space at all. However, to encode the files to a lossless format would take significantly more time than encoding the files to the WAV format.

Lossless audio formats

Lossless audio formats (such as the most widespread FLAC, WavPack, Monkey's Audio) provide a compression ratio of about 2:1.

Lossy Compression

A lossy compression method is one where compressing data and then decompressing it retrieves data that may well be different from the original, but is close enough to be useful in some way.  The advantage of lossy methods over lossless methods is that in some cases a lossy method can produce a much smaller compressed file than any known lossless method, while still meeting the requirements of the application.

What do we recommend

Everyone has their own favourite format, but our choice is not based on a favourite listening format.  Audiophiles will select a lossless audio format for maximum quality retention while my daughter chooses MP3 to fit as many songs as possible on her small MP3 player.  Ipod users may well use Apple's proprietary format.

We recommend FLAC.

Our decision is based on the time it takes to rip your music files.  We believe the Flac format provides the best compression of the lossless formats.  We recommend that you use the highest quality encoding you can.  The biggest expense in moving a music collection from your CD's to a portable digital format is your time.  You only want to do this once, so think about it the first time and only do it once.  There are numerous software programs out there that can take lossless files and convert them on the fly to lossy formats when you need to put them on your MP3 player or USB stick.

Storge Requirements by file Format

The table below provides estimates for the amount of disk space required to store 100 typical audio CDs using various formats and bit-rates.  From this you can now estimate the amount of storage space you would require for your music collection.  Don't forget to allow for future growth of your collection.

Redundancy / Backups

This is a term regularly used in the computer field.  It relates to data safety.  You spend all that time creating your music collection, getting the tags correct and the album images that go with it.  This has taken a lot of your time.  You don't want to have to do this again.  That means you need to have your data backed up.

Modern Network Attached Storage (NAS) devices are available that have two or more disk drives in them.  The two drive units can be configured so that the disk drives mirror one another.  That is that what is written to one drive is also written to the other.  In this way you always have an exact copy of you files.  If one disc drive fails you have not lost your data.  We would recommend that this is the minimum configuration you use.  More advanced NAS devices can have more drives fitted and they have the ability to to retain your data in the event of one drive failing.  This gives you greater flexibility in the amount of storage you have to use.

I have to be really honest here, but in the data world they say that you should always have an additional backup of your data stored away from your normal storage location.  This is for the eventuality of some catestrophic failure.  Something like your house burning down or someone stealing your data.  At a minimum the first level of security is a must.  We will leave the second up to you, but the use of hard drives connected via USB ports to back your data up is an option you might consider.