Re: podcasts?

On 7/12/05 2:47 PM, "Curt Fischer" typed:

>
> Have you ever tried a side-by-side comparison? The difference is
> noticeable, although perhaps not with a 196 kbps mp3, which is what the
> guy was talking before my top quoted response above.
>
> My understanding of the mp3 encoding process is not detailed, but I
> thought that more or less, Fourier transforms of the source are taken as
> functions of time (which involves inevitable frequency cutoff due to the
> finite time domain over which the FT is taken). Next, peaks in the
> frequency domain for a given time point are "sharpened" by removing
> lower-intensity frequencies present around the peak frequency. This
> works because of some sort of masking phenomenon with human hearing that
> says that if you have a say 50 dB sound at 440 Hz then no one can hear a
> 30dB sound at 441 Hz. This sharpening provides most of the
> compression, right, but is obviously a lossy process, right?

Of course I agree that it is "lossy." It's just not a simple frequency
filter or other straight-ahead waveform alteration. It's based on some
high-falutin' psychoacoustic stuff having to do with eliminating irrelevant
information.
There's a good explanation in Sound on Sound:
http://www.soundonsound.com/sos/may00/articles/mp3.htm

At any rate, for spoken word even a bit rate of 128 should be plenty fine
for even the most discerning ear. Better than the radio in your car, for one
thing.

.

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