Advanced Audio Processing Flashcards
Procedural Programming takes what approach?
Structural
Arduino has this form of programming.
Procedural.
Procedural Programming is a series…
of functions, one leading to the next.
Is Procedural Programming flexible?
No.
Is Procedural Programming more or less abstraction?
Less. We dont know how it works
Which analogy can be referred to when considering Procedural Programming Abstraction?
TV Remote.
What is the second form of programming?
Object Oriented Programming.
In Object Oriented Programming, programs are…
divided into smaller sections called objects.
Object Oriented Programming is…
reusable.
Is Object Oriented Programming more or less abstraction?
More. We can understand what happens better.
Is Object Oriented Programming more or less flexible?
More.
What are a key part of Object Oriented Programming?
Classes.
What are classes?
Blueprint for something.
What software similarly uses classes?
Unreal.
What do classes do?
Encapsulatescomplex data.
Classes allow you to define…
custom data types.
Classes can do what with other classes?
Inherit.
What do classes contain? (4)
Data members of different types
Function members
Constructor
Destructor
What are classes in relation to objects?
Blueprints.
What is unique about a classes name?
Normally starts with capital letter.
What files are classes made into?
.cpp and header
What is an object?
Instance of class.
What are the three access modifiers?
Public
Private
Protected
What is the default access modifier?
Private.
What does the protected access modifier do?
Only allows code with class to inherit from it.
Objects have… (2)
States and behaviours.
Where are object states stored?
in member variables.
How does object expose behaviour?
Through member function.
What do member functions work on?
objects internal state.
What is encapulation?
hiding the internal state of object.
What are the key features of classes? (4)
Ease of debugging
Maintenance
Encapsulation
Reusability
What two things can be inherited?
States and Behaviours
What is the largest umbrella class called?
Parent class.
Typical buffer range?
32 - 1024 samples
Smaller buffer = ___ latency
Lower latency
smaller buffer, ____ computational cost
Higher CPU cost.
What is the buffer tradeoff?
Dropout.
What is dropout?
Buffers empties faster than it refills
Buffer uses…
FIFO.
What are the two terms used for buffer input and output?
push and pop.
What is audio callback?
Periodic function that processes audio.
What is AudioBuffer?
A class.
AudioBuffer contains…
a reference variable.
AudioBuffer uses…
call by reference.
AudioBuffer must be larger than…
the max amount of either input or output channels.
What are the two types of reference parameters?
Call by Value
Call by Reference
What does Call by Value do?
Copy OG data sent to function
Doesnt affect OG data
What does Call by Reference do?
Has direct access to OG data
Will overwrite OG data
What classes uses Call by Reference?
AudioBuffer.
What is the difference between pure virtual and virtual?
Pure Virtual need defined.
Subjects are…
Broadcasters.
Observers are…
Listeners.
Subjects send…
Updates to Observers when event occurs
Functions should be…
small and do one thing.
two examples of static delays
comb filter
slapback
two examples of variable delays
flanger
vibrato
max delay calc
buffer / SR * 1000
min delay calc
1 / SR * 1000000
what is max delay measured in?
milliseconds
what is min delay measured in?
microseconds
what type of data type causes artefacts in delay line?
int / whole numbers
what is fractional delay?
allows precise float point number divisions on buffer samples
what is interpolation?
technique to approximate values that lie between samples in buffer.
How does linear interpolation work?
it draws a line between two points and takes approximationof half way point.
Two pros of linear interpolation
improves sound of modulating delay line
computationally efficient
Linear interpolation has audible effect on… (3)
Low pass filters
phase distortion
aliasing
buffer modulation range must…
fall between min and max delay line values.
sampling operation contains… (2)
write operation
read operation
should read or write occur first during sampling operation?
read.
linear system changes
amplitude and phase
in linear systems, the waveform is…
not modified
examples of linear systems (3)
gain
panner
delay
what is a non linear system?
changes waveform, adding additional frequency content
examples of non linear systems (3)
compression
distortion
ring mod
distortion is…
non linear
as non linearity increases…
harmonic content increases
what is half wave rectification?
all negative amplitude samples are changed to zero
what is full wave rectification?
negative amplitude values are changed to identical positive values
what harmonics is THD bases on?
2 to 6
low THD means…
low distortion
odd symmetrical=
only odd harmonics
even symmetrical=
only even harmonics
asymmetrical=
both harmonics
distortion effect pros (2)
cheap to run
memoryless
IIR (5)
feedback network
low latency
low cost
can be analogue
no linear phase filtering
FIR (5)
no feedback network
high latency
high cost
only digital
linear phase filtering
crossover filter criteria (3)
flat pass band with no distortion
max attenuation in stop band
output of filters should sum to flat response
Butterworth meets…
all three criteria
higher order filters have
steeper slopes
how steep should filters be?
as steep as possible
what is the butterworth issue? (2)
when crossed over, filters are completely out of phase
EQ boost at crossover
What is the butterworth solution?
Linkwitz-Riley Filter
How do you make a Linkwitz-Riley filter?
Two butterworth filters in series
What response does Linkwitz Riley have?
flat EQ
What does a detection path do?
Detects how much gain a signal should be reduced by
What scale does the detection path work in?
dB
What process happens at the start of the detection path?
Linear to dB conversion
What are threshold, ratio and knee known as?
Static characteristics
Gain change doesn’t happen
Instantaneously
Gain change consists of what two parameters?
Attack and release
What process happens at the end of the detection path?
dB to linear conversion
What is the full signal chain of the detection path?
Linear to dB, Static Characteristics, Gain Change, Gain Smoothing, dB to Linear
