Built-In Processors, Constants, and Switches (Part I)

Let’s improve on our previous example and add level control to the output signal.

signal Microphone {
        default:        0.0
        rate:           AudioRate
        reset:          MasterReset
        meta:           'Microphone input'
}

signal MainOutput [2] {
        default:        0.0
        rate:           AudioRate
        reset:          MasterReset
        meta:           'Main stereo output'
}

AudioIn[1] >> Microphone;

MainOutput >> AudioOut[1:2];

# Amplify the microphone signal 3.98 times (12 dB) using the Level() processor
Microphone
>> Level (
        gainType:       'Linear'
        gain:           3.98
        offset:         0.0
        bypass:         off
)
>> MainOutput;

Level() is a built-in processor block. As its name indicates, Level() amplifies or attenuates an audio stream when active. Just like Stride blocks, Stride processors have ports and properties.

The Level() processor has six ports and four properties.

Port	Name	Direction	Type	Connection	Access	Default	Required
1	input	input	SRP	single	>> LABEL	none	no (1)
2	output	output	SRP	multiple	LABEL >>	none	no (1)
3	gainType	input	CSP	single	property	Linear	yes
4	gain	input	CIP, CRP, SIP, SRP	single	property	1.0	yes
5	offset	input	CIP, CRP, SIP, SRP	single	property	0.0	yes
6	bypass	input	CBP, SBP	single	property	off	yes

CBP:constant boolean port CIP:constant integer port CRP:constant real port CSP:constant string port CBP:constant boolean port SIP:stream integer port SRP:stream real port LABEL:block label

¹ Warning issued during compilation if the port is left unconnected.

The input and output ports of Level() are not exposed using properties. Connection with the processor block are possible with the stream operator.

The gainType property, sets the amplification or attenuation level in dB (Decibel). gain exposes an input port that can accept connections from output ports of type control real or constant real. In this example, the property has been assigned a real. Real is one of the basic types. All basic types are constant blocks. in case of real, its output type is constant real.

The bypass property, as its name indicates, allows bypassing the processor block and establishing a direct connection between its audio stream input and output ports. bypass exposes an input port that can accept connections from output ports of type boolean. In this example, it is assigned the keyword off. off represents one of the two boolean values in Stride, the other one being on. They both connect to boolean input ports.

constant LevelGainValue {
        value:  3.98
        meta:   'The gain value of Level()'
}

switch LevelBypassSwitch {
        default:        off
        reset:          MasterReset
        meta:           "Switch to control the bypass port of Level()"
}

AudioIn[1] >> Microphone;

MainOutput >> AudioOut[1:2];

# Amplify the microphone signal 3.98 times (12 dB) using the Level() processor
Microphone
>> Level (
        gainType:       'Linear'
        gain:           LevelGainValue
        offset:         0.0
        bypass:         LevelBypassSwitch
)
>> MainOutput;