Re: Prepping for new iPod

>Am I corret that VBR is preferable because the software somehow
>automagically knows when to reduce the BR when it won't matter, thus
>resulting in a smaller file with roughly the same sound quality?

VBR: not magic, just clever coding.  But, yes, that is exactly what it does.

>I read the FAQ at http://www.mp3-faq.org/faq3.html#3.16 but I'm still not
<entirely clear on the benefit of "jstereo"


Joint stereo: this is "mid-side" encoding...fewer bits stored while
preserving (for the most part) the stereo image.  Mid-side works like this
(I think.)  Take  left and right channels.  Figure out what audio info is
common to both, and store that to the "mid" channel.  Sum the dis-similar
audio info from L & R into a "side" channel.  Storage (for most acoustically
recorded music) ends up being quite a bit smaller than storing independent L
& R.  To reconstruct the stereo image on playback: feed the "mid" channel
equally to L & R.  Mix in the "side" channel to L and mix in a phase
reversed "side" R.  Violá, you get (automagically) a stereo image.

A little mod-side history from the pre-computing era:

Mid-side recording was a favored recording technique from long before the
days of audio compression.  Back in the early days of FM radio, when many FM
radios were mono (esp. car radios) and it's still with us with stereo TV
broadcasts, due to the number of mono TVs still out there, mid-side
recording was favored because of it's "mono-stereo compatibility," i.e. you
still get an acceptable mono sound when you sum L+R on mono playback
equipment.  (The "side" info cancels out.)

I used to record concerts for radio broadcast this way 20 years ago.  I had
a great old AKG tube stereo mic.  Once capsule of the mic was oriented right
at the performers and set to a cardioid pattern.  This capsule captured the
"mid" signal got recorded to one channel.  The other capsule was oriented 90
degrees away (pointing to the side walls) and set to a figure-8 pattern.
This captured the "side" info and was recorded to another channel (on analog
tape usually, but I continued using this technique right up through the
PCM-Betamax era and into the DAT era.)  You could then "decode" the mid-side
on playback (or mix-down) with either a mid-side decoder (expensive little
devices) or "organically" decode the mid-side right in your mixer: feed the
"mid" track into a stereo channel panned to the center.  Split the "side"
track into two with a "Y" cable, with one of the "Y"s phase reversed.  Feed
the two "side" signals into two stereo channels panned hard right and left.
Set the level of the center-panned "mid" channel at a comfortable level.
Slowly fade up the right and left panned "side" channels and you will
gradually hear a beautiful stereo image "blossom" into existence.  It's kind
of spine-tingling, actually.

I know of one radio producer who still regularly uses mid-side recording:
Jack Loeffler (among other things, famous for being Edward Abbey's best
friend.)  Jack still hangs a single stereo mic and records mid-side to DAT,
even when he records classical music in the concert hall.





-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Timothy Luoma
Sent: Tuesday, May 13, 2003 9:56 AM
To: [email protected]; [email protected]
Subject: [ephpod] Re: Prepping for new iPod



On Tue, 13 May 2003 09:38:42 -0600, Gordon Harris
<[email protected]> wrote:

> One thing to watch out for:  if you encode using VBR, the vbr header in
> the mp3 file may become "invalid" after tagging with some tagging
> software.

Am I corret that VBR is preferable because the software somehow
automagically knows when to reduce the BR when it won't matter, thus
resulting in a smaller file with roughly the same sound quality?

> As to which encoding switches to use, I'm sure there are folks out there
> with more informed opinions than me.  I tend to use the extremes myself,
> in terms of vbr quality settings.  For music (in my case, classical) I
> use the highest quality VBR with true stereo settings.

I read the FAQ at http://www.mp3-faq.org/faq3.html#3.16 but I'm still not
entirely clear on the benefit of "jstereo"


> Borders is now selling some unabridged audio books that have appealed to
> me.  The longest so far has been 17 cds.
> With those low quality vbr mono settings, an entire cd still ends up
> being smaller than 30 megabytes...which is more easily "digestible" by
> the iPod with it's 32megs of NVRAM.

Interesting.

Thanks.

TjL




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