Overview

ST Headphone Virtualization module

Discussion

The HPV module provides functions to handle audio virtualization on headphones. Goals of this module are to have a virtualization effect and to feel sounds less aggressively for the ears. Front channels (from stereo or multichannel files) are not heard on the side close to the ears but are narrowed in front of the listener, while surround and rear sounds are played around the listener. Some reverberation and Out of Head effects inside the algorithm gives greater virtualization and allows feeling smoother sounds (attenuation of HP vibrations).

The HPV module supports 1.0, 2.0, 5.1 and 7.1 interleaved 32-bit I/O data at a 48 kHz sampling frequency, with a minimum input frame size of 2ms (96 samples per channel). For MIPS optimization reasons, frame length must be a multiple of 4 samples.

Type Definition

typedef struct _ModuleSTHeadphoneVirt
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 nAPIResult;                             // Return status for last call into the ST API
    INT32 audioMode;                              // Audio mode 1 - C, 2 - L,R, 7 - L,R,C,Ls,Rs, 11 - L,R,C,Ls,Rs,Csl,Csr
    INT32 lfeEnable;                              // Enable LFE on input stream
    INT32 enable;                                 // Block enable
    INT32 strength;                               // Strength (0 - 100)
    INT32 enableHeadTracking;                     // Enable head tracking
    INT32 azimuth;                                // Head rotation (-179 - 180) degrees
    void * pGlobals;                              // Points to the global variables structure
} ModuleSTHeadphoneVirtClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
nAPIResult	int	state	0	0	Unrestricted
audioMode	int	const	0	2	Unrestricted
lfeEnable	int	const	0	0	Unrestricted
enable	int	parameter	0	1	0:1:1
strength	int	parameter	0	0	0:1:100
enableHeadTracking	int	parameter	0	0	0:1:1
azimuth	int	parameter	0	0	-179:1:180	degrees
pGlobals	void *	const	1		Unrestricted

Pins

Input Pins

Name: in

Description: audio input

Data type: fract32

Channel range: 2

Block size range: 96:4:480

Sample rate range: 48000

Complex support: Real

Output Pins

Name: out

Description: audio output

Data type: fract32

MATLAB Usage

File Name: st_hpv_module.m

 M = st_hpv_module(NAME, AUDIOMODE, LFE_ENABLE)
 Audio Weaver wrapper for the ST Headphone Virtualization module.  Arguments:
   NAME - name of the module.
   AUDIOMODE -  1 - C, 2 - L,R, 7 - L,R,C,Ls,Rs, 11 - L,R,C,Ls,Rs,Csl,Csr
   LFE_ENABLE - enable LFE on input stream
 Copyright (c) 2017 DSP Concepts, Inc.  All Rights Reserved.
 Author:  Chris Perry