Send and Receive Audio Effects
Geprüft mit Version: 5
In this lesson we'll look at controlling our signal flow using Send and Receive effects. Send effects allow us to route a duplicate of an audio signal to another group or effect in our mixer enabling complex signal flows. We'll look at using sends to route signal to a reverb audio effect.
Send and Receive Audio Effects
- 00:00 - 00:02
In Unity's audio mixer
- 00:02 - 00:04
the send and receive effects
- 00:04 - 00:06
give us a great deal of control
- 00:06 - 00:09
over how our signals are routed
- 00:09 - 00:13
through the mix and particularly to effects.
- 00:13 - 00:16
In this scene we have four game objects,
- 00:16 - 00:19
each with an audio source and an audio clip
- 00:19 - 00:22
loaded that's a loop of a music track.
- 00:23 - 00:29
In our mixer we've setup two effect return tracks.
- 00:29 - 00:32
These are normal groups which have respectively a reverb
- 00:32 - 00:36
on reverb return and an echo effect
- 00:36 - 00:38
on echo return.
- 00:38 - 00:40
Currently they are not receiving
- 00:40 - 00:43
signal from any other the other tracks in the mixer.
- 00:43 - 00:45
But if we want to get a signal to them
- 00:45 - 00:50
we can do that using the send and receive effects.
- 00:50 - 00:53
Let's start with our arpeggio sound,
- 00:53 - 00:55
which sounds like this.
- 01:00 - 01:02
What we're going to do is that we're going to use
- 01:02 - 01:06
a send effect to split the signal so that our
- 01:06 - 01:08
arpeggio will continue to be routed
- 01:08 - 01:10
through the master output but will
- 01:10 - 01:12
also have a duplicate of it's signal
- 01:12 - 01:15
with a controllable volume sent
- 01:15 - 01:17
in this case to the reverb return.
- 01:17 - 01:20
So first we're going to go to our reverb return track
- 01:20 - 01:23
and we're going to setup our destination, our receive.
- 01:23 - 01:25
We're going to choose Add - Receive.
- 01:26 - 01:29
Now it's important to note that the
- 01:29 - 01:32
sequence of these effects in the channel strip
- 01:32 - 01:34
is very important.
- 01:34 - 01:37
In this case the signal from the receive effect is
- 01:37 - 01:40
coming in to the chain after the reverb,
- 01:40 - 01:42
meaning that it's signal will not be processed
- 01:42 - 01:43
by the reverb effect.
- 01:43 - 01:46
What we're going to do is move the reverb down
- 01:46 - 01:49
so it's in the chain after the receive.
- 01:50 - 01:52
Now we're going to go to our arpeggio and we're going to
- 01:52 - 01:54
apply a send effect, we're going to choose
- 01:54 - 01:56
Add - Send.
- 01:56 - 01:58
Now we'll see over in the inspector
- 01:58 - 02:03
that we have a choice for what bus to route the send to.
- 02:03 - 02:06
The term bus comes from the world of
- 02:06 - 02:09
audio mixers in which a bus can be used
- 02:09 - 02:12
to route signal from one channel
- 02:12 - 02:15
to another or two multiple other channels.
- 02:15 - 02:17
In this case the choice is between
- 02:17 - 02:19
routing to a receive effect
- 02:20 - 02:22
or to a duck volume effect.
- 02:22 - 02:25
For more on duck volume effects
- 02:25 - 02:27
check out the information linked below.
- 02:27 - 02:32
We're going to choose our reverb return receive effect.
- 02:33 - 02:37
Now we'll notice that a send level becomes visible.
- 02:37 - 02:40
This is how much duplicated signal
- 02:40 - 02:43
is being routed to the receive effect.
- 02:43 - 02:46
We're going to start playing and turn that up
- 02:46 - 02:48
so we can hear the effect happen.
- 03:09 - 03:11
And you can hear when I stop it we get
- 03:11 - 03:13
that nice reverb tail
- 03:13 - 03:17
tailing off there because now the arpeggio sound
- 03:17 - 03:20
has been routed through the receive effect,
- 03:20 - 03:23
through the SFX reverb plugin
- 03:23 - 03:26
and that's creating that nice cycle acoustic impression
- 03:26 - 03:30
of our sound being played in a large space.
- 03:30 - 03:33
What reverb effects do is they simulate
- 03:33 - 03:36
the reflections of sound
- 03:36 - 03:40
bouncing off of surfaces and returning to the listener
- 03:40 - 03:41
in an acoustic space.
- 03:41 - 03:44
Our synthesiser sound never occurred in an acoustic
- 03:44 - 03:47
space so it has no natural reflection
- 03:47 - 03:50
and we're adding those using the reverb effect.
- 03:50 - 03:52
It's worth noting when we work with
- 03:52 - 03:55
reverb effects via sends and receives
- 03:55 - 03:58
that the dry level should be turned all the way down
- 03:58 - 04:01
so that we don't duplicate the unaffected signal.
- 04:02 - 04:05
It's also worth noting that the order
- 04:05 - 04:10
of the attenuation and the send in our group is important.
- 04:11 - 04:14
Currently the attenuation effect is before the send,
- 04:14 - 04:17
meaning if we turn down volume
- 04:17 - 04:20
using the attenuation effect the signal will stop
- 04:20 - 04:22
passing to the send, let's give that a try.
- 04:25 - 04:28
We can hear the trail trails off
- 04:29 - 04:31
and the sound ends.
- 04:31 - 04:34
If we reorder these effects we'll get a different effect.
- 04:34 - 04:36
We're going to place the attenuation after the end
- 04:37 - 04:39
and what you'll hear is that by
- 04:39 - 04:43
placing the send before the attenuation effect
- 04:43 - 04:47
the send is not going to have it's volume turned down,
- 04:47 - 04:50
it will still receive volume
- 04:50 - 04:53
before the attenuation turns the signal down.
- 04:53 - 04:56
The result is that the send is going to continue sending
- 04:56 - 05:00
signal out even though the main channel is turned off.
- 05:11 - 05:13
What we can hear in this case is that whether or not
- 05:13 - 05:16
the volume is turned down the send is still
- 05:16 - 05:19
getting it's volume out to the reverb return
- 05:19 - 05:21
and not what we're hearing is only
- 05:21 - 05:24
the wet signal of the reverb
- 05:24 - 05:27
coming back in to the main mix via the reverb return.
- 05:27 - 05:29
This can be interesting for some non-traditional effects
- 05:29 - 05:32
but typically you're going to prefer
- 05:33 - 05:35
attenuation followed by your send.
- 05:35 - 05:38
It's also worth noting as I mentioned earlier
- 05:38 - 05:41
that if the receive effect is after,
- 05:41 - 05:43
for example the reverb in this case,
- 05:53 - 05:56
we're going to receive no effect, so it's important for any effects
- 05:56 - 05:58
that you want to process your signal to be
- 05:58 - 06:01
placed in the chain after the receive effect.
- 06:01 - 06:04
Now one of the other major uses of sends
- 06:04 - 06:06
is that we can use it to process
- 06:06 - 06:09
multiple channels with the same effect.
- 06:09 - 06:11
So in this track we also have
- 06:11 - 06:14
a percussion element.
- 06:14 - 06:17
And what we can do, by adding a send
- 06:17 - 06:20
to that and routing that also to the reverb,
- 06:20 - 06:24
we can add reverb, the same reverb
- 06:24 - 06:25
to both of our tracks.
- 06:37 - 06:40
So we can hear this gives us a very
- 06:40 - 06:42
consistent psycho-acoustic impression,
- 06:42 - 06:46
which is especially important if we're aiming for realism.
- 06:46 - 06:48
To have things passing in to the same reverbs
- 06:48 - 06:51
so that they feel like they're emanating in the same environment.
- 06:52 - 06:54
It's also possible to use send and receive effects
- 06:54 - 06:58
to route one signal to multiple effects.
- 06:58 - 07:00
What we're going to do is we're going to send our
- 07:00 - 07:05
arpeggio additionally to our
- 07:05 - 07:07
echo effect on our echo return group.
- 07:08 - 07:10
We're going to add a receive effect
- 07:10 - 07:12
to the echo return and move it up in the
- 07:12 - 07:15
chain so that it's signal will pass through the echo.
- 07:16 - 07:18
Then on the arpeggio we're going to add a send
- 07:19 - 07:22
and assign it's output to
- 07:22 - 07:24
the echo return receive.
- 07:24 - 07:27
once that's assigned we can test.
- 07:47 - 07:50
And you can hear with that nice tail
- 07:50 - 07:54
that our arpeggio is now being passed to both
- 07:54 - 07:57
the reverb return and the echo return
- 07:57 - 08:01
groups that we've created here via the two receive effects.
- 08:01 - 08:03
What's great about this setup is that we can
- 08:03 - 08:07
control the levels individually using the send volumes
- 08:07 - 08:09
and we can really achieve a lot of flexibility
- 08:09 - 08:11
in our mix this way.
- 08:11 - 08:14
It's also worth noting that this is a common
- 08:14 - 08:18
audio industry best practice because
- 08:18 - 08:22
processing audio signals, especially with reverb can
- 08:22 - 08:24
be very processor intense.
- 08:24 - 08:27
Having a reverb on each of these tracks
- 08:27 - 08:33
could have a serious CPU resource cost at run time.
- 08:33 - 08:35
So minimising our use of effects
- 08:35 - 08:38
by sending multiple effects to the same
- 08:38 - 08:40
reverb on a return track
- 08:40 - 08:42
is going to save us some CPU
- 08:42 - 08:45
resources that we'll probably need elsewhere in our game.