Re: [Audacity-devel] Automation [was: Audio I/O rewrite]

[Anthony A. O. <Ant...@ep...>]

On Tue, 04 Feb 2003 21:45:47 -0800, Dominic Mazzoni wrote:

>Let's separate the discussion into two parts:

>1. What's the proper way to handle the application of
>    automation, i.e. when you want to apply all existing
>    controls, including gain, pan, volume envelope, and
>    time track?

>2. What sort of additional automation do we want to add
>    in the future, and how should the interface work?

>My own personal opinion is that the idea of automation is
>very comfortable to people with experience as recording
>engineers.  It has its history in mixing boards with
>mechanical controls that would move the sliders for you.
>(Now they're all electronic, right?)

There's a few types of fader movement. Some use the faders to remote control
actual rack units, which are analog (Euphonics), some are completly digital,
many automatable consoles use motor faders, many are touch sensitive through
capacity circuitry(skin activates it, a pen doesn't), some faders don't move but
allow you to record automation nevertheless.

All those consoles cost a lot of money, so you'll usualy just have professionals
using those.



>While I want Audacity to be useful to people with that
>background, I don't know if the paradigm for automation
>is necessarily the best one.  Specifically, I don't think
>that a user should slide a control around while the project
>plays back, and have that control's movement recorded.
>At least, that shouldn't be the main way to do it.  I think
>that the volume envelope is a lot more intuitive, myself,
>especially for people who have never used a mixing board
>before.

In any case, faders are just one way to enter the data. I wouldn't count on most
users to enter their automation data via faders. I for one almost never use them
during editing. I use the many tools in Protools to generate, manipulate and
delete automation data. 

Automation handling has many very good examples to draw from.

First of all, automation is always non-destructable, meaning it can be changed
at any time and is referenced live during playback. Our envelope is a good
example.

Gain and volume automation are usualy the same thing. I say usualy, because some
applications do make a distinction.

For Protools and Logic Audio, the volume automation(envelope is a bit misleading
btw-that commonly describes instrument parameters) IS the fader and visa-versa.
The fader reflects the automation data.

Vegas has volume automation, and then an additional gain control, which is
processed after the volume automation. You therefore have two gain controls.
This helps in adjusting the overall level of a track(or buss) without too much
fuss.

You would however be surprised how little this second volume control is missed
during regular use. Logic and Protools fave fairly simple ways to select the
automation data of an entire track(and project if you wish). I for one don't
realy enjoy having to go back and listen to all the automation I've created and
see whether it's still ok with that big overall change. I might have to edit
some stuff again.

We already support volume automation in a hard to edit manner, but I'll list the
most basic automation data :

- Volume -
Needs at least 10 bits resolution, meaning 0.1 dB steps from +12dB down to
-30dB. Protools actualy interpolates this data down to the sample level, as well
as Logic, though Logic only uses a 7 bit fader resolution for user input. This
is seen by most people as Logic weakest point for mixing purposes.


- Panning -
Fairly straight forward. You have to decide how to handle stereo panning, as
there are several ways to do this. Personally I prefer to have panning controls
for each channel of a stereo track, like Protools offers it. Let's me have more
interesting mixing options for music and post work.
Resolution is usualy 7 bit, which is enough for many people. 8 Bits wouldn't
hurt.


- FX parameters -(future)
Most VST plugins have 7 bit parameters, save for the pitch wheel. I'm not shure
about that one.

The most important thing is consistency in representation, editing and
manipulation. Protools draws a lot of its enormous power in using the same tools
to cut, copy, past and move automation data, as it does audio or midi data. All
tools work the same way.

Logic has some important features too, that we can capitalize on. It has
exellent selection and moving tools for automation.

Protools for example only lets you select automation like it lets you select
audio. It behaves much like our selection tool. You cannot however select two
automation points and move those around with your mouse in Protools.

If you can, download a demo of Logic Audio 5 or later and take a look at the way
it handles automation. It's an almost exact copy of Protools minus a bit of
intuitive tool use of Protools but plus all those great automation editing
features.

You can select different connection lines between automation points(spline,
linear, smooth) and even change their shape too.

IF you're looking for a reference, take look at that. The editing capabilities
will be fleshed out with discussion I'm shure.

I'd like to point out another important feature of Logic here. You can flip open
an extra track to display the automation data. It isn't overlayed on top of
other data, as Vegas does and which I find very unmanagable. It also doesn't
force you to see and edit only one type of automation data for that track, as
Protools does.
Logic lets you open and close another track display for autmoation parameters.
This way coordinating volume and panning becomes much easier and we're probably
not going to stop at that. Having the autmation of several parameters visible at
once it very helpful.

 Tony