Dynamic System Configuration

[WSTxda]

Device Type Profiles

This document outlines the parameters used in the dynamic audio system configuration for various devices in the ViPER4Android framework. Each profile is defined by six integer values (X;Y;Z;A;B;C) that configure frequency bands and gain adjustments to optimize audio output. These parameters are applied through the DynamicSystem and DynamicBass classes, leveraging digital filters such as PolesFilter for band separation and Biquad for additional processing.

Parameter Definitions

Parameter	Name	Unit	Range (Typical)	Description	Example (Open-Back Over-ear Headphone)
X	Low Freq X	Hz	5 - 1000	Lower cutoff frequency of the bass band processed by Filter X.	50 Hz
Y	High Freq X	Hz	1500 - 25000	Upper cutoff frequency of the bass band processed by Filter X.	9000 Hz
Z	Low Freq Y	Hz	800 - 14000	Lower cutoff frequency of the secondary band (mids/treble) processed by Filter Y.	6000 Hz
A	High Freq Y	Hz	7000 - 25000	Upper cutoff frequency of the secondary band (mids/treble) processed by Filter Y.	18000 Hz
B	Bass Gain	-	0 - 100	Gain applied to the bass band defined by Filter X, controlling bass intensity.	10
C	Side Gain X	-	70 - 150	Lateral gain applied to the Filter X processed signal, adjusting stereo width or dynamics.	80

Notes

• Units:
  • Frequency parameters (X, Y, Z, A) are integers in Hertz (Hz), set directly via SetPassFilter in PolesFilter.
  • Bass Gain (B) and Side Gain X (C) are integers in normalized scales, internally converted to floats (e.g., via SetBassGain(float) and SetSideGain(float, float)).
• Side Gain Y: The code suggests a second lateral gain (sideGainY), but it is not present in the six-value profile, implying it may be fixed (e.g., 1.0) or derived internally.
• Compression and Limiting: Unlike earlier assumptions, explicit dynamic compression or limiter thresholds are not directly represented in these six values. Such effects may occur indirectly via Biquad processing or additional modules not covered here.

Parameter Name Explanations

1. Low Freq X (X)

• Name Origin: "Low" denotes the lower boundary of the bass band; "X" refers to the Filter X in PolesFilter.
• Purpose: Sets the starting frequency of the bass band, ideal for tuning sub-bass or mid-bass response.
• Range: 5 Hz (deep sub-bass) to 1000 Hz (upper bass).
• Example Use: 50 Hz in open-back headphones captures natural bass without excessive emphasis.

2. High Freq X (Y)

• Name Origin: "High" marks the upper boundary of the bass band; "X" ties to Filter X.
• Purpose: Defines the upper limit of the bass band, separating it from midrange frequencies.
• Range: 1500 Hz to 25000 Hz, depending on device needs.
• Example Use: 9000 Hz in open-back headphones includes lower mids for a balanced, airy sound.

3. Low Freq Y (Z)

• Name Origin: "Low" indicates the lower edge of the secondary band; "Y" links to Filter Y.
• Purpose: Marks the start of a secondary band, typically focusing on mids or treble, processed separately from bass.
• Range: 800 Hz (low mids) to 14000 Hz (lower treble).
• Example Use: 6000 Hz in open-back headphones emphasizes mid-highs for clarity.

4. High Freq Y (A)

• Name Origin: "High" is the upper edge of the secondary band; "Y" corresponds to Filter Y.
• Purpose: Sets the upper limit of the secondary band, adjusting the extent of treble frequencies.
• Range: 7000 Hz to 25000 Hz, covering high frequencies.
• Example Use: 18000 Hz in open-back headphones ensures wide, detailed treble.

5. Bass Gain (B)

• Name Origin: "Bass" targets low frequencies; "Gain" indicates amplification.
• Purpose: Controls the intensity of the bass band defined by Low Freq X and High Freq X.
• Range: 0 (no gain) to 100 (maximum gain), likely mapped to a 0.0-10.0 float scale internally.
• Example Use: 10 provides a mild bass boost in open-back headphones, preserving natural sound.

6. Side Gain X (C)

• Name Origin: "Side" suggests stereo or lateral adjustment; "X" associates with Filter X.
• Purpose: Adjusts the amplitude of lateral components in the bass signal, influencing spatial perception or dynamics.
• Range: 70 to 150, a broader scale possibly representing gain or an indirect dynamic parameter (e.g., threshold).
• Example Use: 80 in open-back headphones offers moderate stereo width for an open soundstage.

Example Configuration

For the Open-Back Over-ear Headphone, the profile is defined as:

<item>50;9000;6000;18000;10;80</item>