BOOT CAMP 194 (27/09/01)
AUDIO RECORDING ON YOUR PC. Part
Thanks to your enquiring and inquisitive minds there is no
shortage of topics for Boot Camp to cover and the next couple of week's we are
responding to a succession of reader's letters and emails asking how to use a PC
as a sound recording device. This week we'll be looking at the rudiments of
audio recording on a PC, next week, putting it to practical use.
Sound came quite late to the PC; they all beep when booting
up and when something goes wrong but up until the late 1980s that was about as
far as it went, sound cards and speakers didn't become standard features until
the early 90's and then they were usually more trouble than they were worth.
Anyone involved with PCs back then will doubtless remember the agonies of
setting up sound in DOS and early versions of Windows; these days we take it all
pretty much for granted. In fact most users rarely give the sound systems on
their computers a second thought, which is a pity because even the humblest PC
can be turned into a sophisticated hi-fi system and a powerful sound recording
and editing studio.
However, most of the queries we've received lately concern a
much more down to earth application and that's to use the PC as a means of
transferring cherished recordings on vinyl records (and even 78s) and tape (open
reel and cassette) to audio Compact Disc. CD has taken over from vinyl and
cassette tape is on the way out and a lot of people want to preserve their
collections or make compilations of favourite tracks on CD. PCs and low-cost CD
writers have made this possible and currently you can pick up perfectly capable
CD writer drives for less than £60; blank CD-R (record once) discs can be bought
in quantity for as little as 15 pence each.
Incidentally, fitting a CD-writer to your PC is quite
straightforward and it's something we looked at in detail in Boot Camp 158
Most CD writers come with software that lets you copy CDs or
make track compilations from several discs but the instructions rarely – if ever
– explain how to make custom audio CDs from records, tapes and other 'analogue'
audio sources. It's not difficult so we'll try and fill in the gaps. The process
breaks down into four stages:
1 – connecting the sound source (i.e. record player or tape
deck) to the PC
2 – recording the sound onto the PC's hard disc drive
3 – organising and converting the tracks
4 – recording or 'burning ' the finished CD
The first stage is easy. Connecting a record player or tape
recorder to a PC is usually just a question of getting hold of the right cable.
Most PCs have two audio inputs, one for a 'high-impedance' source, such as a
microphone (or the 'phono' output from a record player), and one 'low-impedance'
or 'line-level' input, which is compatible with the audio outputs on devices
like tape recorders, CD players etc. In theory you can connect the output from a
record player to the microphone input on a PC, and sometimes it works okay but
in my experience the results are often disappointing. Where possible it is
better to leave the record player connected to the amplifier (or pre-amplifier)
and connect its audio output (but not the speaker output!) to the PC.
On most PCs the audio input sockets are usually 3.5mm stereo
'minijacks' whereas the audio outputs on audio and hi-fi devices are generally
push-fit phono sockets, so you will need a stereo minijack to phono adaptor
cable; these are readily available from most audio and video dealers, usually
for less than £5. When connecting audio equipment to your PC make sure you use
the right socket, they're not usually very well labelled and almost always in an
inaccessible location on the back, behind a jungle of cables. If in doubt
consult your instruction manual and use a torch. By the way, don't be tempted to
connect the headphone sockets on audio equipment to a PC, the output level can
be quite high and it can cause all sorts of problems.
At this point it's worth saying a few words about audio
recording formats. The vast majority of CD decks in home hi-fis and in-car
players can only replay discs recorded in the standard CD-Audio (CD-A) format (a
few recent models can also play discs recorded with MP3 format tracks). Most PC
recorders record sound in the .wav (wave) format; the quality can be very good
indeed but .wav files can only be played on a PC and in order to hear them on a
CD player they have to be converted to CD-A files. One other point to bear in
mind, .wav files can take up a lot of space – reckon on at least 10Mb per minute
– so you will need a fair amount of free disc space on your disc drive if you
are going to fill a 74 or 80 minute audio CD with music.
Single programs that can both record and convert files from
one format to another are available but in my view they are either highly
specialist and therefore difficult to use, not sufficiently flexible or they are
expensive, therefore I suggest using two programs, one to make the recording the
other to prepare the files for recording to disc.
Windows comes with an audio recording utility called Sound
Recorder (Start > Programs > Accessories > Entertainment/Multimedia)
but it is far too basic for our purposes. There are numerous shareware and
freeware audio recorders for Windows available for download from the Internet
and we'll be looking at a couple of them next week. Some of the more advanced
programs have facilities for removing scratches, hiss and pops from vinyl
recordings and it's very easy to get drawn into the technicalities of bit-rates,
sampling, mixing and editing but at this stage I suggest you stick with simple
recording software until you've mastered the basic techniques.
There is also plenty of 'high-end' file conversion, track
compilation and CD 'burning' software to choose from but several programs
combine all three functions and for beginners this can be very convenient.
Next week – Audio recording on a PC, part 2
The process of recording a CD-R or CD-RW disc in a CD writer
Measurement of resistance in relation to an alternating
Motion Picture Experts Group audio layer 3 -- digital audio
compression system commonly used to send files containing audio and music over
Whilst we're on the subject of sound, here's a nifty freeware
program that turns sounds on your PC into visual displays. Although the Sound
Frequency Analyser download is only 31k this powerful little utility shows both
the amplitude of sounds passing through your PC as a constantly changing
waveform, and as a colourful Fourier Transform, which represents the spectrum of
the frequencies contained in the sound. Even if you're not interested in the
science and mathematics of sound analysis it's fascinating to watch the patterns
on your PC screen. Sound Frequency Analyser is a zip file and it can be
downloaded from: http://www.relisoft.com/freq.zip