The second grouping of criteria from D jaffe's 1995 paper evaluating synthesis from the perspective of purpose, situation and aims for the user, rather than listing synthesis methods individually. Examples have been given to demonstrate each criteria. Part II focuses on the implementation and efficiencies that need to be considered for the processing environment, platform and system architecture, the limitations, constraints, power and memory.
IN A FIXED AMOUNT OF TIME TO COMPLETE A PIECE AN EXTREMLY LONG
FEWER ITERATIONS == LESS-REFINED RESULTSTURN AROUND TIME =
QUOTE: "determining the
efficiency of an algorithm
is more complicated than
it might at first appear. It
is not merely a matter of
comparing processing
benchmarks. Numerous
aspects of a technique
and its implementation
come into play,"
The aspects of the GS techniques and their
implementation that come into play can be divided
into 3 categories:- a memory, b processing requirements c control stream heaviness
IaMEMORY REQUIREMENTS
SINE E.G.Amem -
WAVETABLE SYNTH
Mathews '69
VARIABLE MEM REQ. Changes
with the parameter values
Vm1 Karplus-Strong
(plucked str)
(waveguidebased
MODELLING):
MORE MEM LO
Pitch LESS MEM
HI Pitch
Ib PROCESSING DETAILS
SINE.G.Bproc -
ANALYTICAL
COMPUTATION
Alt. techniques for sinewave generation
EGB1proc
marginally stable 2-POLE FILTERS
EGB2proc
EVAL. of COMPLEX PHASOR
Gordon,
Smith
'85
EGB3proc
WAVEGUIDES
Smith,
Cook 92
II (b) PROCESSING POWER
1. quite
COMPLEX"
2. depends on the
PROCESSOR ARCHITECTURE
poor
EXPENSIVE:
EGIIB
Finite Element
Modelling
(numerical
INTEGRATION of
DIFFERENCE
EQUATIONS that
Descrb. Masses &
Springs
BUT wellsuited to: ARRAY -
PARALLEL PROCESSORS
good EFFICIENT
1. active code fits within
the CACHE of a RISC
CHIP RUNS FASTER
than an active code set
that OVERFLOWS THE
CACHE
AFreed, Rodet
and Depalle 93
2. With MINIMUM
CHANGES in PROGRAM
FLOW
well
supported
by:
a. DSP
processors
& other b. HEAVILY
PIPELINED ARCHITECTURE
PURPOSE BUILT
HARDWARE
INCREASES
ENORMOULSY
THE EFFICIENCY
OF A
TECHNIQUE
GOOD
B Some techniques
have a PROCESSING
REQUIRMENT that
CHANGES with the
PARAMETER VALUES
Time domain
implementation of
CHANT
more EXPENSIVE as FREQ RISES
MORE PITCH PERIOD/SEC.
MORE ADDONS and more TABLE
LOOKUPS PER OUTPUT SAMPLE
with MORE MEM/MORE PROC
= NARROWER PEAK with 32
Harmonics than with 8 -
changes behaviour of the
technique
Formant Wave
Function FOF
synth. by
adding
overlapping
vocal tract
IResp.
c CONTROL STREAM ATTRIBUTES
density/heaviness of control stream
Problem esp. for RT impl.
may need 2 processors - then expensive
processing to get data from control
processor to the sound procesor
even wth
just 1
processor -
is their
enough DISK
SPACE/BW
for the cntrl
stream data
ie is control
stream
density >
RAM
Dispersion pattern:
sys. FAIL wth sporadic,
CLUMPED, LARGE DENSE
BURSTS of parameter
update mess,
e.g. ENTIRE AMP ENV chngs with
note data, at be of each note
more easily manageable:
REL STEADY STREAM OF
WELL-SPACED FAIRLY
DENSE CNTRL MESS.
More EFF. feed ENV DATA BY BREAK
POINT THRU THE NOTE 1 POINT AT A TIME
TRADE OFF
well known axiom
A single period of a waveform
stored in memory
EGA1mem
use a non-interpolating
'drop-sample' oscillator
stored in memory
in a HUGE TABLE
Greater
Memory
less
processing
EGA2mem
stored in memory in
a SMALLER TABLE
a more expensive OSC that
interpolates between
samples in the table
Optimised
Mem - but
MEM < EG1
PROC> EG1
EGA3mem
Precomputed
resultant. WAV:
ƒ WAVE * A ENV
MAX
MEM
MIN RT
PROC
how SPARSE /
DENSE is the
CONTROL STREAM
what CLASS of SOUND can be represented
what is SMALLEST
possibel LATENCY
do ANALYSIS TOOLS exist
1 to 5 relate to parameter behaviour, physical, intuitive, wellbehaved, perceptible
changes, sound ID robust e.g. sounds good on more than 1 pitch/resonance of the instr.