Re: [linux-audio-dev] Recording: What do we need now ?

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Subject: Re: [linux-audio-dev] Recording: What do we need now ?
From: Paul Winkler (slinkp_AT_ulster.net)
Date: ti heinä  27 1999 - 19:42:27 EDT


Much good fodder for discussion...

A note on where I'm coming from:
I'm mostly a user, not a developer. I can hack together csound orcs and
scos, and I can hack enough perl and python to do fun things with
automatically generated csound scores, but that's about it. I can sort
of barely read some C. So I don't have much to offer any projects in the
making. I am pretty good at writing user-level documentation, which I
know some of you guys hate, so maybe that would be of use.

My personal wish list:

First, re. items 6 and 7 from Dave's list:
Hard-disk recording and soundfile editing.

I think these are more than closely related: they are (or should be)
integral. Sure, there's plenty of use for a good 2-channel editor, but
once you go beyond that, there is so much benefit to be had from a real
hard-disk recording system. And a hard-disk recorder without good
editing capabilities gets annoying pretty quickly (e.g. Multitrack.)

Having spent some time this year recording an album on a 24-channel
ProTools system, I must say that doing it _right_ is a pretty daunting
task.

Part of what makes ProTools so great is the extensive, powerful signal
processing. We can't (currently) hope to compete with $30,000 worth of
dedicated DSP's, nor is it realistic to think we can put together a
system of free plugins rivalling a burgeoning industry where plugins
cost > $500 apiece, BUT:

Leaving aside signal processing _entirely_, the ProTools
recording/editing interface alone is miles beyond anything we have.
SLab, MultiTrack, Mix... I don't think any of these could possibly be
rebuilt into something comparable. It would almost certainly have to be
a new project. Imagine Mix's interface, only you have 32 (or is it 64?)
channels instead of 9, there's no arbitrary limits on file length, each
channel has totally non-linear non-destructive editing (so it's like a
32-channel editor with unlimited undo), and zooming in on envelope
curves actually works... you get the idea. Now imagine that this system
also records audio (in 24-bit precision, no less). Then add pro-quality
dsp, plugins, the ability to record mixer fader movement from an
external interface, the ability to sync to external analog or digital
recorders...

Now, that's a tall order. The demands on the hard drive must be _very_
intense. Without those Digidesign DSPs to do all the mixing, the CPU and
memory load would be pretty heavy too. I have no idea how Digidesign
gets ProTools to respond to edits as quickly as it does. I would think
the disk would just be seeking like crazy. At one point we were using 32
channels of audio simultaneously, with editing on about half the
channels, and doing overdubs on that with perfect synchronization and no
dropouts. I don't know how much latency there was but it sure seemed
like you could make an edit, hit "play" and hear it really fast. (This
was on a Mac G3 - 233 MHz I think, 96 MB ram, with one SCSI drive
dedicated to audio. This is not an exotic machine these days by any
means. But then, as the guys at the studio told me, "The Mac doesn't do
much except hold it all together.")

I bring up ProTools because, as long as we're looking at what needs to
be done, I think we may as well aim REALLY high. It's worth considering
how close we can come to meeting such specs.
I would just about die to see a free software recording/editing
application project that could, in principle, accomplish these things,
even at a lesser scale. Hell, as little as 8 channels of ProTools with
only 2 or 4 channels of I/O would be an enormously powerful system for a
home studio. And as the price of CPU and hard drives continues to drop,
it would only get better.

I think the most likely way a project like this could actually get done
is somewhat like the way GIMP seems to work: if a small team of core
developers concentrated on the recording / editing / mixing system and
the interface, and left dsp entirely up to plugin authors. Probably
there wouldn't need to be time wasted on developing a new toolkit since
the GIMP people already did that for us. :) (But let's not argue about
toolkits again... yet.) In a few short years, GIMP has come from nowhere
and is arguably giving Photoshop a very, very good run for its money
(for web graphics, at least; not prepress, sadly).

So it IS possible.

It seems to me that part of the problem with SLab and Multitrack is the
authors wanted to do too much themselves; they wrote lots of dsp code
for a framework that wasn't working very reliably yet. The other problem
is the closed development model. Unless B. Nagels turns up, all the work
he did on Multitrack is useless because nobody but him can fix all the
bugs.

Re. Slab: I haven't checked it out lately; maybe it's better now. I'm
not so inclined to give it another try because I was one of those who
disliked the interface... too complicated and I _still_ couldn't do a
lot of the things I wanted ... an example of inappropriately aping
physical hardware, I think.

At this point, it must be noted that Snd already has a lot of what's
needed for my hypothetical system: it already supports many channels; it
already has a plugin API (or rather several ways of doing it -- IMHO a
very good idea as you can in principle do quick hacks with tools like
sox, or cool things with csound, or whatever.). And Snd already has a
lot of editing capability. But:

--I can't figure out what the license terms of snd are; would it be ok
to modify and redistribute?
--It's not really set up to be a hard-disk recorder: I haven't figured
out how to make it work full duplex, if it even can. Likewise, it's not
really designed for intensive realtime work so I'd be surprised if it
would work well.
--It doesn't really have any way to do non-destructive automated mixing:
the envelope interface is OK, but not really comparable to what ProTools
and similar systems have.

---------------- paul winkler ------------------
slinkP arts: music, sound, illustration, design, etc.

zarmzarm_AT_hotmail.com --or-- slinkp AT ulster DOT net
http://www.ulster.net/~abigoo/
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