I must have been in junior
high school when I bullied my father into buying me a transistor radio.
He was a pioneer in the early days of radio and stomped around the house
muttering that unless you knew how to build a radio yourself out of a coil
of wire and an oatmeal box you had no business listening to one. For him
it was all about the technology. For me it was about the music.
Itís still about the music but the technology is rearing its ugly head
again. All I had to do to listen to my transistor was slap in a 9-volt
battery and tune into my favorite station. After more than 30 years of
progress, Iím having to learn how to build the radio. Itís a digital radio,
made of bits and bytes, but itís a whole lot more complicated than turning
that analog dial.
To get the gist of digital sound it helps appreciate what came
before ó analog sound. Physicists can probably give you a concise
definition, but for non-scientists who took their last physics classes
when dinosaurs ruled the earth, hereís how I see it. Analog is physical.
In the analog world, something really happens. The gears turn and your
analog watch ticks over another minute. The needle bumps up and down on
the grooves of a vinyl disk and sound waves reverberate. Digital is made
up of digits, ones and zeros, which represent on and off. Since there are
two options, they are called binary digits, or bits. A group of 8 bits
is a byte. A megabyte (MB) is 1,048,576 bytes.
On my ancient transistor radio my only choices were between AM and FM,
between WIP and WMMR. Now itís more complicated. Digital audio files come
in a variety of formats. Within those formats they may be available at
different quality levels to accommodate fast and slow Internet download
speeds. Depending on the type of file I select I may need to decide to
use a particular media player that recognizes that file format. I can download
the audio files for later listening, or ďstreamĒ them, listening to them
on the fly. My old transistor came in a brown leather case. Now, I can
even download ďskinsĒ on my software media players, changing the way they
look with the click of a mouse.
By far, the most popular format for listening to music is MP3. Young
people know all about this. Oldies like me had to learn it.
MPEG (pronounced EM-peg)
stands for Moving
Group. MPEG contains
both video and audio data. DVD movies use MPEG for their video compression.The
audio is encoded in . . .
. . .MP3
which stands for MPEG-1 Audio Layer-3. MP3 is a compression algorhythm.
An algorhythm is a procedure or a formula for solving a problem. (The word
has nothing to do with rhythm, so get that out of your head. The term comes
from the name of a mathematician, Mohammed ibn-Musa Al-Khowarizmi, who
lived in Baghdad in the 9th Century or thereabouts.)
Back to MP3. The compression algorhythm works by discarding high and
low frequency sounds that only cockroaches can hear. There are different
levels of MP3 compression. 128 bit and above compression gets almost CD-like
quality. MP3 compression reduces the file size to about 10% of the original
or even smaller.
Most MP3 files are made from audio CDs, sometimes in violation
of copyright laws. Audio files are extracted from a CD and put
on a computerís hard drive using software called a Ripper and then
converted to MP3 format using another piece of software called an Encoder.
Ripping is also called DAE (Digital
A Ripper will convert a music CDís files, which are in a .CDA format into
a .WAV file. Dale Swafford offers a six hour course on making music CDs,
so donít expect me to go into detail. Just toss around the terms ripper
and encoder and youíll look like you know what youíre talking about.
People share MP3 files over the Internet. This is the main reason why
the copyright controversy has arisen. P2P (Peer-to-Peer)
Networking, is the technology used by Napster, Grokster, KaZaA and
file sharing sites. In a nutshell, their software enables users to search
the hard drives other people around the world who use the same program.
Users can designate which files are open to the outside and allow people
to download them. Although music sharing P2P operates over the Internet,
P2P is different than the client-server model used by the Internet.
There are also MP3 files that you can purchase for a small sum, or download
for free. Most free MP3 are delivered
at 24kbps ó not CD quality, but they sound pretty good to me when played
on my computerís sound system. Legal free MP3s are usually played by obscure
artists. Try out mp3.com to
get a feel for whatís available. Iím streaming (playing right off the Internet,
not downloading) a collection of Celtic songs from MP3.com as Iím writing
So how do you play the darn things?
Obviously, you can play them on your PC. If you have a computer with Windows 98 or above, you probably have the Windows
Media Player already installed, or you can download something like
the RealPlayer Some of
these players are called jukeboxes, which typically means that they
can handle several different file formats and organize audio files into
playlists, or user-constructed sequences of songs. Nobody Ė but nobody
Ė plays an entire ďalbumĒ any more. The new best thing is individually
crafted compilations. One well-known jukebox is MusicMatch.
There are also portable MP3 listening devices, ranging in price from
about $100 to a whopping $500+ for the Creative Labs Nomad Jukebox with
40GB of memory. You can either download music, or rip and encode your own
audio CDs. No more carrying around your originals, worrying about them
getting scratched, misplaced or stolen. MP3 players are rugged and virtually
skip-proof. Depending on the memory size, they can play hundreds of hours
If you download your MP3s from the Internet, you can also burn them
onto CDs and play them on your regular stereo system or boom box.
MP3 has been around for a while and it has competition. Microsoft has
come up with a competing file format, WMA (Windows
which claims to produce a higher quality file at half the size of MP3.
Ogg Vorbis is a patent-free compression technology, comparable to WMA and
is media that comes to you in chunks, called packets, rather than making
you wait until an entire file downloads. It is mainly used over the Internet.
A little bit of the file downloads, is put in a buffer, or holding area,
then starts playing. While youíre listening (or watching; this works for
video as well) the next packet is already downloading and poising itself
in the buffer. With streaming media you can start listening to a large
file right way without waiting for the whole thing to download. Real
Networks was in the forefront with this; their files have an extension
of .RA WMA files can also stream. Many radio programs are streamed ó I
often listen to shows I missed on NPR at <www.npr.org >. They stream
in Real Audio, Windows Media Audio and Apple QuickTime.
Some of the older formats are still alive and well.
was designed to record and play back music on digital synthesizers,
such as an electronic keyboard. The sounds in a MIDI file are actually
embedded in the sound card, so the quality of a MIDI file depends totally
on the quality of the sound card. 32 different instruments, actual sound
samples, can be replicated by the wavetables on soundcards and can be combined
and shuffled to sound like 128 instruments ó an entire orchestra in a chip!
MIDI files are considered old-fashioned: they sound synthesized, rely
on the quality of the soundcard and canít replicate human vocals. Youíll
find them used as backgrounds to Web sites, in karaoke files (the .kar
format is a variation of a MIDI) and, of course, in piano bars too cheap
to spring for a baby grand. MIDI files do have the advantage of being small
files because they are just sending instructions to the sound card.
audio file format was created by Microsoft. Wave files ó identified
by a file extension of .WAV, are used for everything from computer system
sounds (ďYouíve Got MailĒ is a Wave file) to the sounds on computer games
and CD-quality audio.
Most WAV files use PCM (Pulse
a generic digital way of transmitting analog information. PCM is also used
in audio CDs and DAT (Digital
PCM files can be compressed using DPCM, or Differential Pulse Code Modulation.
Rather than recording all the 1 and 0s, DPCM just records differences between
consecutive samples. APCM (Adaptive
analyzes a succession of samples and predicting the value of the next sample.
DPCM and APCM are LOSSY formats, which means that they compress data by
removing some of it, usually redundant information. You probably wonít
notice the missing data, but the file canít be returned to its exact former
state after undergoing lossy compression.
My father is probably chuckling from the grave. After all these years,
Iím learning how to build the radio.