Subject: From: Date:

RE: [ECS] More on Audio Data compression (was: [ECS] Help with Log States) Michael David Tue, 27 Oct 1998 23:42:10 -0500

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Hi Dan!

Actually, AC3 really refers to the compression scheme, which is a "lossy"
compression scheme.  Most often you will find 5.1 mixes that are AC3
encoded, which is labled as "Dolby Digital", on DVD's and Lazer Disks.  In
addition to 5.1 channels of audio, the spec also supports 4 channel, stereo,
and mono material.  Although far from transparent, AC3 encoded stereo
material holds up rather well.  Unfortunately, the encoders are still pretty
expensive.

As an aside, one of the services we offer at my facility is DVD authoring.
As you can imagine, our audio department does a fair amount of 5.1 mixing
now, which is all AC3 encoded.  AC3 is not the best compression scheme, but
for surround mixing, it sure beats the heck out of Dolby Surround  encoding.
Although I think I could live with AC3 stereo for my music server, I'd
prefer a "lossless" compressions scheme.  Of course, I doubt I can afford
either.  :)

We are currently working on the worlds first DVD Video/DVD ROM/DVD Audio
hybrid disk for Warner Records.  The neat part about this disk is the DVD
Audio component. The recently ratified DVD audio spec allows for sample
rates of 44.1K to 192K, and resolutions of 16, 20, and 24bit, and employs
Meridian Lossless Packing (MLP), a very impressive compression scheme.  For
you audiophiles out there, the 192/24 stuff I've heard is really stunning.

There's a lot more to the DVD Audio spec, but I won't bore you all with it
here.  Suffice it to say, I can't wait till DVD audio players become
available so I can get one - and control it from ECS (see - I did get it
back on topic!  :)

Cheers!

Michael David
michael@michaeldavid.com


-----Original Message-----
From:	Dan Carrington [mailto:dc_grafx@microworks.net]
Sent:	Tuesday, October 27, 1998 2:03 PM
To:	ecs-list@vancouver.ml.org
Subject:	Re: [ECS] More on Audio Data compression (was: [ECS] Help with Log
States)

Hear Hear on the first part,  I fully agree with you!  A question
though.  Is AC3 a compression scheme?  I only know it as a fully
seperate 5 channel plus sub system.  I have never heard of it as a
compression scheme.

Dan Carrington




Michael David wrote:
>
> Hi Garnet!
>
> As a recovering audio mixer (no matter how hard you try, you never really
> get it out of your blood...), I plead guilty to being an audio purest.  :)
> So, my first inclination is to shy away from a compression scheme that
will
> yeild audible artifacts because they'll drive me nuts.  For the same
reason,
> it has gotten to a point where we don't go out to movies anymore because
all
> the theaters we have tried in our area have one problem or another with
> their playback chain.  And, for $7.50, I expect the theater to sound
totally
> awesome.  As it is, my living room generally sounds better than many of
the
> theaters in our area.  In addition, as an added benefit, I can hit pause,
> and hit the restroom when the beer takes it's toll. :)
>
> Having said all that, there must be some form of compression out there in
> the 250 to 500Kb range that is fairly transparent.  I just haven't found
it
> yet (AC3, maybe?).  And, ultimately, maybe the answer is to go with
> uncompressed .wav files.  With the cost of hard drives as they are now, it
> wouldn't be that awful.
>
> Or, maybe we'll just stick with the changer and run it with that Slink-e
> software.  I don't remember who posted that link, but that pair looks
great,
> and well worth the money.  In addition, their software now supports MP3
> files.  If you guys haven't checked it out, I encourage you to do so.
>
> Cheers!
>
> Michael David
> michael@michaeldavid.com
>
> -----Original Message-----
> From:   gbailey [mailto:gbailey@attcanada.net]
> Sent:   Monday, October 26, 1998 9:02 PM
> To:     ecs-list@vancouver.ml.org
> Subject:        RE: [ECS] Help with Log States
>
> You guys realize that almost every radio station in the country plays
their
> music off a hard drive. They use a commercial compression setup, but it is
> pre mp3. The local rock station here uses 10GB hard drives. What you are
> doing is far higher fidelity than they can do !
>
> --
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