What is granular synthesis?
Wikipedia has this to say on the subject of Granular
Granular synthesis is a basic sound synthesis method
that operates on the microsound time scale. It is often based on
the same principles as sampling but often includes analog technology.
The samples are not used directly however, they are split in small
pieces of around 1 to 50 ms (milliseconds) in length, or the synthesized
sounds are very short. These small pieces are called grains. Multiple
grains may be layered on top of each other all playing at different
speed, phase and volume.
The result is no single tone, but a soundscape, often a cloud, that
is subject to manipulation in a way unlike any natural sound and
also unlike the sounds produced by most other synthesis techniques.
By varying the waveform, envelope, duration, spatial position, and
density of the grains many different sounds can be produced.
The result is usable as music, sound effects or as raw material
for further processing by other synthesis or DSP effects. The range
of effects that can be produced include amplitude modulation, time
stretching, stereo or multichannel scattering, random reordering,
disintegration and morphing.
Okay, what is a grain cloud, then?
Again, from Wikipedia:
In music a cloud is a sound mass consisting of statistical
clouds of microsounds and characterized first by the set of elements
used in the texture, secondly density, including rhythmic and pitch
density (Roads 2001, p.15). Clouds may include ambiguity of rhythmic
foreground and background or rhythmic hierarchy.
Why would I want a grain cloud?
Grain clouds produce wonerfully interesting textures
from the most mundane of source material. Take any recording you
have laying around, plug it into Atomic Cloud, and you'll be amazed
at what you get back. If you're interested in synthesis or sound
design, it's hard to ignore the sonic possibilities of grain clouds.
What does Atomic Cloud sound like? Can I
hear a little bit before downloading?
Sure, here are some demos:
Guitar: original source
file | grain cloud 1 | grain
source file | grain cloud
Chimes: original source
file | grain cloud
Is Atomic Cloud a standalone application,
or a plugin (VST, RTAS, AU, DX)?
Atomic Cloud is a standalone application, and does
not require anything additional in order to run. You use it just
like you would use any other application, usually by double-clicking
on the application icon. Once you've generated a grain cloud that
you like, you can render it to disk using Atomic Cloud, and then
bring your grain clouds from Atomic Cloud into a host application,
such as Cubase, Logic, or Pro Tools, but Atomic Cloud does not presantly
run as a plugin of any sort.
Why doesn't Atomic Cloud run as a VST plugin?
Getting a really smooth cloud can take quite a lot
of CPU power. Basically, the more overlapping grains you have at
any given time, the more CPU cycles Atomic Cloud will use. Losing
the overhead of the VST host and any other VST plugins means you
can get a much denser grain cloud on the same system, so I decided
to make Atomic Cloud a standalone program.
What operating systems does Atomic Cloud
At the moment, Atomic Cloud is Windows-only.
How do I use Atomic Cloud?
Atomic Cloud is easy to use. After starting the
application, click the "Browse" button, and select an audio
file to use as the source material for the grain cloud. Atomic
Cloud will load most uncompressed audio file formats. The demo version
of Atomic Cloud is limited to using 10 second or shorter source files,
but the full version can load audio files of any length to use as
source material. Playback will start automatically, and can be stopped
and started with--surprisingly enough--the stop and start buttons.
Before looking in depth at the parameters, it is important to understand
that Atomic Cloud employs a playback head, just like a regular audio
editor. The Scan
Rate controlls the speed of this playback
head. At a neutral Scan Rate of 50, the playback head will scan through
the audio file at real-time. Grains are generated from the source
material found at the playback head. However, the Jitter parameter
introduces randomness into the equation. As you increase the Jitter
from 0, grains are generated at random distances farther and farther
away from the playback head. What this basically means is that at
a Scan Rate of 50, and a Jitter of 0, with a grain rate and grain
size set high enough that you don't hear any space in between grains,
you will essentially hear the file as if it were being played back
in a normal audio editor. This effect can be heard by choosing the Normal
Playback preset, and I suppose, could be considered
the most neutral of settings. Start adjusting the controls away from
this in order to get more interesting effects.
Parameters on the GUI are as follows:
- Start and End Location: You can
load an audio file of any length, but you might only want the grain
cloud to be generated by a small portion of the file. Use the Start
and End Location to constrain the playback head by setting limits
on what portions of the audio file can be used to generate the
- Grain Rate and Grain Size: The
Grain Rate controls how quickly grains
are generated. Low settings
produce very few grains per second, whereas high settings produce
many grains per second. The Grain Size controls
how long each grain is. High grain rates and long grain sizes are
capable of generating remarkably smooth textures, but also tend
to take quite a bit of CPU power. You will likely not be able to
turn both the Grain Rate and Grain
Size up all the way without
running out of CPU cycles.
- Buffer Rate: The rate at which
each grain is played back. This essentially has the effect of altering
the pitch of each grain.
- Scan Rate: How quickly the playback
head moves through the audio file. With low levels of Jitter, grains
are generated near the playback head.
- Jitter: How closely the generated
grains are constrained to the playback head. A very low jitter
setting, with a very high grain rate has the effect of playing
the file back pretty much as it would sound regularly. High jitter
settings randomize the sound greatly.
Amp Level: Since any number
of grains can be generated at a time--depending mostly on your
grain rate and grain size choices--it's quite easy to get digital
clipping. The built-in limiter controls this, but generally speaking,
higher grain rates and grain sizes should often be accompanied
by lower amp levels, so as to avoid clipping or excessive limiting.
- Clip Indicator: Unsurprisingly,
the clip indicator indicates when digital clipping has been detected.
Click it to clear the indicator. Clipping should really only occurr
if you've turned off the built-in Limiter.
In this case, you should turn down the Amp Level in
order to avoid clipping, or turn the Limiter back
- Limiter: Atomic Cloud is equipped
with a built-in Limiter. This comes in
handy, because long grains are likely to overlap, so it is very
easy to generate a grain cloud that starts clipping if you don't
watch the gain. The best solution for this is to turn the gain
down until you don't have any clipping, but the built-in Limiter will
watch the gain for you, and turn things down when necessary.
- 16/24 bit Playback/Recording: Playback
and recording can occur at either 16 or 24 bit, regardless of the
bit rate of the source file. 24-bit output is not available in
the demo version of Atomic Cloud.
- Automatic Sample Rate Sensing: The
output sample rate is set to whatever the source file's sample
- Buffer Size: The Buffer
Size parameter mainly controls how smooth
the amplitude envelope of each grain is and how much latency there
is between when you move a control and when it affects the audio.
As with all audio applications, a smaller buffer takes more CPU,
but generally results in a better sound. In this instance, shorter
grain sizes should generally be accompanied by smaller buffer sizes,
since the effect of a large buffer will be most noticeable on short
grains. However, larger grain sizes can be accompanied by
larger buffer sizes in order to reduce CPU load without affecting
the sound too terribly much.
- Recording: Atomic Cloud can render
the grain cloud to disk as you listen to it (note:
recording is disabled in the demo version). This is the best
way to record audio from Atomic Cloud, as the audio data is written
straight to disk while you listen without any sort of DAC or ADC
conversion. Audio files can be recorded in either 16 bit or 24
bit formats, and the rendered sample rate (i.e. 44.1kHz, 48kHz,
96kHz) will be the same as the source file. So, if you load in
a 96kHz file, you'll get a 96kHz grain cloud.
- Presets: Presets of your favorite
parameters can be saved and called back at the bottom of the application.
Saving and deleting of presets is disabled in the demo version.
Still need help?
Ask a question on the Sound
Borb / Atomic Cloud Forum.