Digital Audio Processing

Sampling Rate and Sampling Period

$f_s = \frac{1}{T_s}$

with:

• $f_s$: Sampling rate in $Hz$
• $T_s$: Sampling period in $s$

Samples and Frames

A frame is a list of a sample for each channel at a given time.

Block/Buffer

A block is a number of consecutive samples for each channel for the same time.

Sometimes this is called a buffer. But that term is used for different things, too.

Samples per Block

This term is ambiguous:

• frames in a block
• samples in a channel in a block

Buffer length calculations

Duration

$\textnormal{duration} = \textnormal{number of frames} / \textnormal{sampling rage}$

umber of frames: number of samples in a single channel of the buffer

Audio Plugin Architecture

Editor: GUI Processor: DSP audio processing code

Processor

Initialization of the processor:

1. createPluginFilter()
2. prepareToPlay()

• can be called multiple times

3. processBlock()

• called for each block providing the buffer to process
• MIDI messages are also provided
• called many times per second
• needs to finish on time
• can still be called when playback is stoppend

Closing the plugin:

1. releaseResources()
2. destructor called

Editor

• Can be opened and closed by user.
• Plugin needs to work even when there is no editor.
• No audio related code in editor!

Resources

WolfSound: JUCE Audio Plugin Development Course

JUCE Documentation

JUCE Tutorials