Subject: Re: [linux-audio-dev] a new application underway
From: Paul Barton-Davis (pbd_AT_Op.Net)
Date: ma loka 11 1999 - 13:41:29 EDT
>I've made it easy to add more channels, but I don't think I need to
>do this anytime soon. A lot of people talk about surround and
>multichannel sound, but when I look around my home studio, all my
>equipment is designed to work with stereo signals (mixers, effect
>processors, synths, drum machines, etc).
actually, in my studio, i don't have this perspective. my mixer, for
example, can clearly handle mono signals quite well, and i use it for
quite a few: the mono inputs sources: mic, prophet-5, matrix-6
synth.
because i had a breakout card built for my soundcards, i don't even
think of them as stereo devices anymore, but as each having two mono
input channels - i have 1/4" jacks on a 1U panel in the front of the
rack that allow me to plug something into, say, channel "1" (right) of
my Trident soundcard, and something else into channel "0"
(left). their outputs go back to separate mixer strips as well.
i spent some time talking with people who use mixers a lot, and asked
them how helpful it was to be able to use a stereo input signal on a
single strip. the verdict: as long as you can group (sync) the faders
for two strips, they didn't care, even when i pointed out that it
consumed an entire extra strip this way. ah, diehards :)
i think it depends in part on what your inputs are. if they really are
stereo signals (stereo soundfiles, devices etc.), then having audio
default to stereo is a good choice. if they are mostly mono (mono
soundfiles, devices, mics, etc), which is often true in live
recording, then it can be a bad choice, computationally.
i noticed that neundo allows both. i'm still thinking about this.
>Hmm, it looks like our designs are actually quite similar. Ecasound's
>inputs do much the same as your input_device-source-strip abstraction
>and ecasound's chains are just like your buses (hmm, where do you put
>additional effect processing... buses or strips?).
like an expensive hardware mixer: both.
this allows you to do semi-global FX and EQ on several different
inputs at the same time (e.g. add the same delay to 4 different
strips). doing this at the bus level is much more computationally
efficient than doing it 4 times (once per strip). on the other hand,
sometimes, you want an effect to just be applied to a single input,
and then you'd do it on the strip:
+--> BUS2 -> FX3 -> FX4 -> OUT1
|
IN1 -> STRIP1 -> FX1 -> PAN -+
|
|
+-->
BUS2 -> FX5 -> FX6 -> OUT2
+-->
|
|
IN2 -> STRIP2 -> FX2 -> PAN -+
|
+--> BUS3 -> FX7 -> FX8 -> OUT3
i'm still working on optimizing the amount of data copying that goes
on in a net like the one above, but it all works just fine for
now. MIDI controllable control elements too :)
--p
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