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| Commentary |
| All Things Must
Pass |
The Little Spinning
Silver Disc is not quite done yet! |
by Rod Nattrass
In the past hundred years or so we have seen a number of different music
reproduction media come and go. Wax cylinders, shellac and then vinyl records,
magnetic recording tape…and now the Compact Disc is about to follow
these venerable standards into the history books. Word in the industry
is that the 44.1 KHz, 16 bit music format may soon be a thing of the past.
The first CD’s came to market in late 1982. By the late eighties,
as the price of the players started to drop, CD sales began to exceed the
sales of vinyl records. The general public enthusiastically embraced the
convenience of a disc that could hold up to 74 (later 80) minutes of 20
to 20,000 Hertz audio with a 96 decibel dynamic range, and a noise floor
below the threshold of hearing.
I recall that when CD’s first came out, audiophiles were somewhat
skeptical of the claims that digital sound was better than analog. In some
ways they were right. A lot of the first releases were simply direct transfers
of the original analog master tapes, which would have been mastered for
the format for which they were intended, the LP record. This would mean
that they had a slightly exaggerated top end, something that was done to
overcome the limitations of the playback medium itself. These recordings
were also limited at the bottom frequencies. You could not print too much
bass information on an LP or the cartridge would literally jump out of
the groove and cause skipping during playback.
The unfortunate result was that the first CD’s that were re-issues
of older material were often somewhat thin and sometimes harsh and brittle
sounding. As the medium matured, the record labels realized that they needed
to re-master older tapes specifically for the CD, and the sound quality
was markedly improved.
Another very important development was the ability for artists to record
their music digitally. By the 90’s more and more studios had become
fully digital. The all digital recordings took full advantage of the medium
and really allowed engineers to exploit the dynamic range and low noise
floor, showing off the technology to its fullest extent.
Slowly but surely, digital technology continued to improve. Better and
better analog to digital and digital to analog converters were designed
that drastically improved sound capture and reproduction. The biggest improvements
came with the implementation of oversampling.
Oversampling helped to deal with something called “aliasing” which
could happen to the signal during conversion from a continuous analog wave
to zeros and ones. When signals approach the Nyquist frequency, which in
the case of the Red Book specification is one half of the sampling frequency
of 44,100 Hertz, or 22,050 Hertz, they can fold back on themselves and
produce nasty sounding digital artifacts. To prevent aliasing from occurring
a “brick-wall filter”, which has a very steep cut off slope,
was used to make sure that no frequencies past 20,000 Hertz went through
to the converters. This kind of filter is both difficult and expensive
to manufacture. A sharp filter like this has its own problems as well;
it tends to ring at the cutoff frequency. Oversampling the signal allowed
the removal of this filter by moving the aliasing up into the inaudible
range. I watched and listened as we went from 2 to 4 to 128 times oversampling.
Finally, the converters got to the point where even die-hard analog audiophiles
were happy to accept the digital medium into their enclaves.
As a result the Compact Disc became the number one audio format, but this
is changing…
More and more people are listening to their music on an MP3 player. They
are downloading their music off the internet to be played back off of either
a hard drive or directly from RAM. The files are often 128 kB (or lower)
MP3’s. These people seem to delight in packing as many songs as possible
into these little gadgets. Many of them do not seem to care about the quality
of the sound at all. They will encode the music files at very low bit rates
so that they can have hundreds (if not thousands) of songs available on
demand. More often than not, they are listening to the music on cheap headphones
or ear buds.
This is a sad state of affairs. It goes against everything audiophiles
believe in. I don’t think any of us would be happy with the mangled
sound quality of a 128kB MP3 sound file. Where does that leave us?
Apple’s iTunes store has chosen to use the AAC (Advanced Audio Coding)
process to encode their files. This format is superior to MP3 in many ways,
and definitely sounds better on lower bit rate files. Some of the other
brands of MP3 players will accept this format, check before you buy.
Hopefully, some clever entrepreneur will realize the need for higher quality
sound files and start up a site with an option to download songs at higher
bit rates. I find 256 kB files to be acceptable, and 320 kB to be almost
as good as the original. With today’s high speed internet connections
there is no reason why this cannot be done. Sure, a 256 kB file is twice
the size of a 128 kB file, but we could probably all live with only 400
songs instead of 800 to choose from.
The other important issue that must be addressed is the headphones. Many
of these devices do not come with very high quality headphones. Spend some
money on better ones after you do some intensive listening tests. Oddly
enough just being expensive doesn’t seem to guarantee anything. Let
your ears be the judge.
At the other end of the quality spectrum, audiophiles now have an ever
increasing selection of titles to choose from in both SACD and DVD-A formats.
The little spinning silver disc is not quite done yet! These formats offer
multi-channel, very high quality audio that will satiate your desire for
superior sound.
I’m still on the fence a bit about multi-channel audio. I prefer
it to be used in the more classical sense of allowing an engineer to capture
the ambience of the space in which the recording was made, as opposed to
having instruments flying around all over the place. But the art of multi-channel
mixing is still very much in its infancy, and I’m sure that everything
that can be done will be done. The good news is that most titles also have
a stereo version of the recording, just in case you don’t have a
listening room with a 5.1 speaker set up.
Of course, the CD is not just going to disappear all of a sudden, anymore
than the LP did. Independent artists will still sell CD’s at their
gigs. Independent and College Radio stations still want a band to send
in a CD. They are going to be with us for a while.
The major record labels should be happy to sell their stable’s music
on the internet. Since they would have no package manufacturing costs and
no physical distribution costs, it makes fiscal sense that they would embrace
this concept. It would also allow the return of the single, as there is
no need to release a whole album’s worth of material all at the same
time. Artists could finish a mix of a song and upload it right away for
immediate public consumption.
This technology also opens the door to re-mixes of songs. There is a new
trend for artists to actually post the multi track files of their songs.
This allows aspiring producers to re-mix the song and post it at a designated
website, where the mixes are usually voted on by the other participants.
I recently recorded a song with three other artists, a drummer from Pender
Island, B.C., a guitarist from Victoria, B.C., and a multi-talented fellow
who provided bass, guitar and harmony vocals from Ohio. I would upload
a rough mix of the song and post it to an FTP site. The other artists would
download the song, come up with additional parts, and then send me back
their part(s) as wave files, which I would download and add to the work
in progress. It was truly amazing.
Ages ago, I remember seeing a rather obscure movie from 1976 called “The
Man Who Fell to Earth” that starred David Bowie. It was a science
fiction movie that was set in the future. The movie itself was unremarkable,
but there was a scene in it where the main character places a tiny little
cube into a device that instantly begins to play music. That scene has
stuck in my head all these years. I have been waiting patiently all my
life for technology to catch up to that scene in that movie.
We are there! |
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