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The WDN Symbian DevZone... Richard Looks at The Beatnik Audio Engine
by Richard Bloor, July 22, 2002
Delivering rich audio content to wireless devices challenges the available
bandwidth with standard compressed files. The Beatnik Audio Engine addresses
this problem with a software synthesizer, which runs using far more compact
files. More significantly it offers games and content developers opportunities for
delivering rich dynamic sound.
Beatnik was formed in 1996 by Thomas Dolby Robertson who had a string of hits
in the early '80s including "She Blinded Me with Science" and as one reviewer
described it 'the charmingly unhinged "Hyperactive!"'. Thomas recognized that
existing audio technologies had significant limitations and his experience in the
music industry led him to believe there was a better way to delivery a rich sound
experience to computer users.
Most audio solutions for delivering sound to PC applications, within web pages or
for any number of software applications rely on either compressing, to some
degree or another, a copy of the sound as it would have been heard when played
or using simple tone generators. These audio solutions have a number of
limitations. To maintain a reasonable sound quality in compressed linear sound
relatively large files are needed. Linear sound also offers the developer only
limited control, often little more than the ability to start and stop the sound
playing. With tone generators only one tone can be created at a time making any
sound rather flat, somewhat like a child’s early attempts to play an instrument.
Thomas Dolby Robertson’s solution was to apply the technology of the MIDI
synthesizer to PC sound creation. Synthesizers had for some time been interfaced
to computers through a standard interface called MIDI (Musical Instrument
Digital Interface). Music (or rather a sequence of timed "notes") is defined on the
PC and instruments played by sending structured commands across the MIDI
interface. The obvious advantage of this technology, when compared to recorded
sound, is that data required to instruct an instrument to play is significantly
smaller than data required to record the resulting sound created. So using a
structured description of sound reduces the data needed to create music. By
itself MIDI, and a number of other structured music description standards such
as XMF or RMF only solve part of the problem. A MIDI interface also offers the
developer the ability to dynamically create music by creating the structured audio
data on the fly or modify the playing of a predefined audio file in real time.
So the Beatnik Audio Engine (BAE) was created, essentially a software
synthesizer whose capabilities were succinctly described by Jeremy Copp, Senior
Vice President, Sales & Marketing as being able to "play any note on any
instrument at any time where an instrument can also be a sound effect or linear
sample, so vocals or sample of a gunshot for example". This ability to play
multiple notes at once is known as polyphony (many sounds).
While Thomas had initially envisaged BAE being used in web pages, it found its
first application in PC games.
The original BAE was designed for use on the desktop. As demands changed
Beatnik modified the original engine to create miniBAE for the mobile phone
market. As this market has burgeoned Beatnik completely redeveloped BAE to
create mobileBAE to more specifically target the wireless market and embrace a
wider range of open standard file formats. In November 2001 it was announced
that BAE had been ported to Symbian OS and implemented as a plug-in to the
Media Server framework.
While BAE’s approach reduces the data required to define the sound it does
require more complex processing. With linear sound any player has to only
decompress and convert the resulting data from Digital to Analog. The Beatnik
solution has to read the structured audio data, sequence the notes and match
them to instruments (which could be custom samples of sounds or voice, not just
built in instruments), in a process known as rendering. The rendered sound is
then mixed to a single audio channel or dual for stereo. In the original target
environment for Beatnik, web audio and gaming, availability of computing
resource to achieve this was not a problem but for the emerging handheld and
wireless devices memory and processor capacity are an issue. Both miniBAE and
mobileBAE address these issues with their ground up development for this type
of environment but also by allowing the device implementation to be tailored in
terms of the number of voices (individual notes) which can be played
simultaneously and the sample rate for the underlying source notes. This allows
the implementation in a device to be tailored closely to the memory and
processing capacity available.
So what can BAE do for the developer. Thomas Dolby Robertson himself noted,
when the relationship with Symbian was announced that "It'll give you a slew of
new ways to annoy the heck out of your friends and colleagues!". While this
flippancy is probably the prerogative of a company founder BAE can do much
more.
Clearly one of the principal applications is in games but equally standard
business applications and consumer applications like messaging can also benefit
from this enhanced audio capability.
In dealing with what is essentially a musical instrument you may wonder whether
using the BAE technology requires a high level of musical ability. Jeremy Copp
commented that "with MIDI it’s pretty easy to string together a piece of content
using one of the many MIDI sequencer packages available. Where this can not be
done the advantage of using standards based file formats means you can go out
on the web and find literally hundreds of thousands of MIDI tunes which will give
any developer a head start”
Beatnik's commitment to standardization is strong. They have been assisting in
defining standards such as Scalable Polyphony MIDI (SPMIDI), XMF and RMF.
SPMIDI has recently been adopted for 3GPP release 5 as the standard structured
audio format for EMS, MMS and streaming media. They are also involved in
development standards as well. Beatnik have been involved the Java Expert
Group defining the Java multi-media framework for the next generation MIDP.
While BAE is an optional component Jeremy commented that the mandatory
components are "not going to meet all of the needs of today’s mobile phones,
providing little more than a simple tone generator, so we expect a lot
manufactures will be implementing the API over BAE"
So applications using BAE can be developed using APIs for Java, C or Symbian
C++.
For Symbian development BAE will be delivered as part of the SDK for individual
devices which will allow developers to create and test applications using the BAE
APIs. While this will be possible within any IDE supporting Symbian
development, in June 2002 Beatnik and Metrowerks teamed up to more deeply
incorporate BAE into the CodeWarrior tool for Symbian to provide improved code
editing and debugging.
It is also possible that in the future other tools will provide further support for
BAE. When I asked Jeremy about Borland or AppForge the response was that
"we understand those environments and what it would take to add the BAE APIs
into them and we will be monitoring the demand."
At the time of writing there were no formal announcements of BAE's inclusion in
any Symbian OS based device. Several sources suggest that it is incorporated
into the Nokia 7650 and the SonyEricsson P800 does have a polyphonic ring tone
capability (and includes a ring tone composer) but none of the literature mentions
Beatnik. When I spoke to Jeremy Copp he would not confirm this speculation
but did comment that “pretty much any new phone is going to have to have
polyphonic ring tone capability, its the next step up in functionality. The
Symbian OS does not, as standard, have a polyphonic engine and BAE plugs into
the Symbian OS audio framework. We are confident that amongst the early
devices there will be a good selection that developers can target."
You can find out more about the Beatnik Audio Engine on Beatnik’s web site (www.beatnik.com).
Thomas Dolby Robertson is also hosting series of workshops (www.headspace.com/seminar2002.htm)organized by
Headspace in London and Helsinki focusing on special composing techniques for
polyphonic tones and mobile game sounds during August. Spaces are limited to
25 people per seminar.
About the "WDN Symbian Guy" Richard Bloor:
Richard Bloor has 16 years experience in the IT industry. His earlier
work was largely in design and development of commercial and
manufacturing systems but more recently has focused on
development and test management of government systems.
Richard Bloor is the Mobile Applications champion at System
Architecture consultancy Equinox of Wellington, New Zealand.
Richard can be reached at rbloor@wirelessdevnet.com.
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