Re: So close, but no cigar (audio quality is poor)
- From: cwdjrxyz <spamtrap2@xxxxxxxxxx>
- Date: Fri, 24 Aug 2007 18:34:32 -0700
On Aug 24, 6:18 pm, JethroUK© <re...@xxxxxxxxx> wrote:
"alex specht" <alexspe...@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:909D6B17-96AF-4E15-8816-4138F67F7B6F@xxxxxxxxxxxxxxxx
So, in conclusion, forget compressed audio. The industry should strive to
present consumer electronics that play back flash memory, in the exact
manner
of a CD (PCM)
A/ Isn't that one for the purists only (e.g. appeal only to 0.000001% of the
populous)?
B/ Is CD quality that good? e.g. the only reason it's not compressed is
because they didn't know how to do it & it's only sampled at around 192k
anyway
CD's became common in the mid 1980's. The standards are 44.1 KHz at 16
bits, which comes out to about 700 kbps per channel, which is about
1400 kbps for the usual stereo CD. This is about the minimum required
to capture the full range of frequencies the human ear can hear with a
little leeway. Another consideration is the noise floor, which
decreases with bit rate and frequency. The CD standards are pushed by
a little classical music, such as the Berlioz Requem, which has a
dynamic range from a whisper in a quiet hall to a perhaps 100+ piece
orchestra, 4 brass bands in the corners of the hall, several solo
singers, and a very large chorus singing and playing as loud as they
can for brief passages. Most rock is much less demanding. One has to
design for the most extreme case. To play back a CD to capture the
full potential requires very fancy filters and D/A converters required
for the bandwidth limits of CD. This made top quality CD players very
expensive at first, but mass production of IC D/A converters and
filter chips has reduced the price of a CD player to a very low cost
except for high end equipment. SACD and DVD-Audio allow a much higher
frequency and bit rate. Often 96 Khz and 24bits are used. Also one can
record 6 independent surround tracks. I record in DVD-Audio, as this
format also will record at CD standards which allows you to put about
6-7 CDs on one DVD-Audio disc. It is especially good for collections.
People knew how to compress sound over 100 years ago. At first a
singer would walk toward and away from the acoustic recording horn to
prevent very low volume levels from being lost in surface noise and
prevent the recording needle from cutting into the next groove. With
electrical analog recording, equalizers were used to reduce the volume
in the bass range and increase it in the high frequency range to
overcome the problems mentioned above. Then the phono preamplifer had
expansion of the bass and compression of the high frequencies to
restore the desired sound fairly well. Also limiting circuits were
used, especially on radio, to keep one radio station from causing
problems with another close by. Compression for CDs would have been
quite possible, but it was not desired. Compression can be done in
many different ways. You may reduce the dynamic range, you may reduce
the frequency range, etc, and you can combine several compression
methods at one time and vary the mix with the current volume of the
music, etc. Thus different compression methods can sound quite
different on some carefully selected material, especially on highly
compressed material. Sounds that tend to bring out the worst in
compression are falling water and applause.
For the web, great compression was needed at first because of the very
limited bandwidth and cost of bandwidth. However the main reason for
using compressed audio on the web today is if you wish for those with
dialup and very low broadband to hear the music without excessive
buffering time or complete download. I can easily play official PCM CD
audio, because I have a DSL download of about 5 Mbps, much greater
than the 1.4 Mbps needed. Bandwidth is now dirt cheap. I have about
500 GB of bandwidth per month on the server of my host that caters to
small business. I never come even close to using this, even though I
have a lot of audio and much more demanding video on my site. In the
US over about 70% of computer users now have broadband of some sort.
Full chip memory likely will replace CDs, DVDs, and HD memory in the
future. I do not know when that will be common. The main problem here
is one of cost. I would expect it to happen for audio before video
because of the much greater bandwidth of video.
.
- References:
- Re: So close, but no cigar (audio quality is poor)
- From: JethroUK©
- Re: So close, but no cigar (audio quality is poor)
- Prev by Date: Re: Media 11 not squashing enough onto disk
- Next by Date: Re: Media Player Stopped Working
- Previous by thread: Re: So close, but no cigar (audio quality is poor)
- Next by thread: Re: So close, but no cigar (audio quality is poor)
- Index(es):
Relevant Pages
|
