On Wed, 13 Jun 2012 12:29:37 -0700, ckozi...
(in article <firstname.lastname@example.org>):
> I'm an audio-video NUT. I've had several jobs as an AV technician or sound
> man and know a few things about the subject.
> When it comes to MP3s most people simply don't understand exactly what kind
> of compression is going on. This is why I feel "compression" is a bad word
> to describe the data parsing that goes on in MP3 files. There is little to
> no DYNAMIC compression via MP3 files. There is DATA compression and
> psycho-acoustic masking going on, but the only dynamic compression I've heard
> is on a MP3 ripped from a digital "remaster" file or CD.
Yes, This is confusing to many people. How do you explain to a layperson that
when FM signals are compressed, the difference between the loudest and the
softest sounds being broadcast is reduced, but when the same station is
"compressed" for Internet radio, the digital data that represents the radio
station's sound is reduced, throwing away up to 97% of the original signal?
> The only area dynamic range *might* be affected by mp3 is on lower
> bitrate(128kbps or lower) files. A lot of high-freq and some low-freq
> information is thrown away at or below that threshold, so you may reduce the
> dynamics of instruments occupying or reaching into those realms. On 192kbps
> and up, I honestly have not heard any such loss.
Dynamic compression of the program material in MP3 files may or may not be
happening. For instance, some radio stations that also broadcast over the
Internet, might take off the program feed either before the stations signal
processing chain (compression and limiting), or after it. If before it, then
the dynamic range is not compromised before digital compression, if after the
radio station's signal processing, then the dynamic range IS compromised.
Also most popular recordings these days are purposely heavily compressed in
order to sound loud and exciting (but they end up just sounding BAD). Many
over-the-air FM stations, that broadcast popular music tend to highly
compress the dynamic range of their broadcast audio in order to sound louder
than their competition in that broadcast market in order to grab the
attention of "dial-twirlers".