5. Computers for audio As well as considering the equipment required to play back your source recordings, you need to consider the equipment to convert your analogue sources into digital audio files on computer. In general this will mean deciding what kind of computer hardware and software you'll need for your particular project. If all your sources are on one medium, it may be feasible to simply transfer them from the playback machine directly to your computer with no other equipment. However, if your source recordings reside on several different media requiring several types of playback equipment (some of which may be highly specialised), it might be more efficient to make an interim stage where the source materials are gathered together in a single format. This way any acoustic sound capture requiring specialist resources can be done in one go (such as a single recording studio session), whilst transfer of the sound to computer can be done in a less resource intensive way. For instance, if some of your sources are gramophone records requiring the use of a recording studio whilst the rest are on vinyl LPs, it makes sense to use one studio session to do all the gramophone capture but to do the LP digitisation elsewhere. 5.1 DAT Any such interim stage may involve transfer of sources to DAT, digital audio tape (or to some other removable digital medium, such as ADAT). DAT uses magnetic tape to record digital information as outlined in section 3.5.1. The tape is housed inside a cassette, which though convenient is actually very delicate; one of the disadvantages of DAT is that it is not particularly rugged and can be susceptible to mechanical failure. The main advantage of DAT is that once sound is recorded, it is digitised: transfer to computer can be done via a digital link. See sections 7.3 and 7.4 for more information on digital transfers. If you do use DAT in this way, it is advisable to keep at least one backup version of the tape in case of failure. DAT machines are fairly straightforward to use, though the user manual should always be read before using. 5.2 Apple Macintosh Apple Macintosh (abbreviated to 'Mac') computers are very widely used in the digital audio world as they have built-in audio hardware and an internal architecture which is efficient at handling audio information. This built-in audio hardware is probably sufficient for many basic digitisation tasks, though it does not allow for direct digital transfers, such as from DAT. The G4 and iMac models can digitise audio at 16-bit resolution, 44.1kHz, and in stereo. However, for professional quality digitisation, it is best to invest in extra audio hardware which can be added to the computer. Such hardware would not be made by Apple but by specialist audio companies, and would be connected to the computer via either a PCI or a USB port. Some professional level hardware comes bundled with software in the form of a sound editor, mixer and processor programme. One of the most widely used programmes is ProTools, made by Digidesign, which comes bundled with Digidesign audio hardware in various configurations. Some audio hardware may only support digital transfers, rather than digitisation from analogue sources. It is important to check manufacturers' specifications carefully before buying. See also section 5.6 on soundcards below. 5.3. PC: Microsoft Windows Microsoft Windows is an operating system widely used on IBM-compatible PC computers. PCs are made by many different companies and their technical specification can vary a great deal. The situation with regard to audio on PCs is somewhat complex as a result. PCs are usually purchased with some built-in audio support provided by a soundcard. Usually these soundcards are designed for game-playing or 'multimedia' (i.e. basic listening capability), and as such are generally unsuitable for professional audio work. There are various options here: either a PC can be bought 'off the shelf', and the low-quality soundcard replaced by one purchased from a specialist dealer, or a PC can be ordered from certain manufacturers to one's own specification. It is important to note, though, that general PC manufacturers will not usually supply professional audio hardware. In this case it is probably best to order a PC with no sound capability, and then to purchase and fit the soundcard yourself. This will take a certain amount of technical expertise. Some relatively low-cost soundcards may be suitable for digitisation purposes. See section 5.6 below. In terms of other hardware specifications for a PC for digitising audio, the main considerations are the amount of RAM (computer memory: at least 128 megabytes is best); the amount of hard-disk storage space (stereo, full bandwidth, or full resolution, digital audio takes up about 10 megabytes per minute, so for an hour's worth of sound that's 600 megabytes; you'll also need much more space than this for any post-digitisation work); the speed of the hard disk drive (if there is lots of audio, a fast disk with a speed of 7200 or 10000rpm will help); and the speed and efficiency of the processor/motherboard combination (a processor running at a minimum of 300MHz is recommended, and different types of processor will give different audio performance). On the operating system side it is important to note that Windows exists in several versions: Windows 95 and Windows 98 have better support for audio hardware than Windows NT and Windows 2000. Audio under Windows NT can be difficult to get working, even if a particular soundcard purports to be 'compatible' with it. The situation regarding the level of audio support under Windows 2000 is not clear at time of writing. There is a selection of software suitable for digitising audio under Windows, and programmes such as Syntrillium's CoolEditPro or Sonic Foundry's SoundForge offer a wide selection of post-digitisation processing. Note that the ProTools system is also available for PC, although it requires a very tightly specified hardware configuration. 5.4 PC: Linux Microsoft Windows is not the only operating system for PCs. Linux is a version of the Unix operating system that runs on PC. It has an advantage over other operating systems in that it is free, as is most of the software available for it. However, audio support under Linux can be confusing, and is not comprehensive. There are two systems of audio support, called OSS (open sound system) and ALSA (Advanced Linux Sound Architecture). An increasing number of soundcards is being supported by both, but support for high-end hardware is patchy at present. There is also no single piece of software for Linux offering ease of use, flexibility and robustness comparable to those for the Mac or Windows systems.
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