File syn_vad.h¶

FileList > audio > syn_vad.h

Zero-Heap Acoustic Voice Activity Detector (VAD) Engine (Q15/Q16 fixed-point). More...

#include "../common/syn_defs.h"
#include "../util/syn_qmath.h"
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

Classes¶

Type	Name
struct	SYN_VAD Voice Activity Detector instance context.
struct	SYN_VAD_Config VAD configuration descriptor.
struct	SYN_VAD_Features Extracted audio frame feature metrics.

Public Types¶

Type	Name
enum	SYN_VAD_Sensitivity VAD sensitivity preset level.
enum	SYN_VAD_State Voice Activity Detection state.

Public Functions¶

Type	Name
SYN_VAD_State	syn_vad_get_state (const SYN_VAD * vad) Get current smoothed VAD state without processing a new frame.
SYN_Status	syn_vad_init (SYN_VAD * vad, const SYN_VAD_Config * cfg) Initialize Voice Activity Detector context.
SYN_VAD_State	syn_vad_process_frame (SYN_VAD * vad, const int16_t * samples, size_t num_samples, SYN_VAD_Features * out_features) Process single frame of 16-bit signed PCM audio samples.
SYN_Status	syn_vad_reset (SYN_VAD * vad) Reset VAD state counters and restore default noise floor.
SYN_Status	syn_vad_set_sensitivity (SYN_VAD * vad, SYN_VAD_Sensitivity sensitivity) Adjust VAD sensitivity preset.

Macros¶

Type	Name
define	SYN_VAD_DEFAULT_ATTACK_FRAMES `2U`
define	SYN_VAD_DEFAULT_FRAME_LEN `160U`
define	SYN_VAD_DEFAULT_HANGOVER_FRAMES `6U`

Detailed Description¶

Implements a low-latency, deterministic Voice Activity Detector for embedded microcontrollers: * Frame-by-frame acoustic analysis (10ms - 30ms windows of 16-bit PCM audio). * Multi-feature extraction: Short-Time Energy (STE), Zero-Crossing Rate (ZCR), and High/Low Spectral Energy Ratio. * Dynamic background noise floor tracking via Exponential Moving Average (EMA). * Configurable attack onset validation and hangover release timing. * Sensitivity presets (Aggressive, Normal, Sensitive).

Public Types Documentation¶

enum SYN_VAD_Sensitivity¶

VAD sensitivity preset level.

enum SYN_VAD_Sensitivity {
    SYN_VAD_SENSITIVITY_SENSITIVE = 0,
    SYN_VAD_SENSITIVITY_NORMAL = 1,
    SYN_VAD_SENSITIVITY_AGGRESSIVE = 2
};

enum SYN_VAD_State¶

Voice Activity Detection state.

enum SYN_VAD_State {
    SYN_VAD_STATE_SILENCE = 0,
    SYN_VAD_STATE_SPEECH = 1
};

Public Functions Documentation¶

function syn_vad_get_state¶

Get current smoothed VAD state without processing a new frame.

SYN_VAD_State syn_vad_get_state (
    const SYN_VAD * vad
)

Parameters:

vad VAD instance pointer.

Returns:

Current VAD state.

function syn_vad_init¶

Initialize Voice Activity Detector context.

SYN_Status syn_vad_init (
    SYN_VAD * vad,
    const SYN_VAD_Config * cfg
)

Parameters:

vad VAD instance pointer.
cfg Configuration descriptor (or NULL for default 16kHz parameters).

Returns:

SYN_OK on success, SYN_INVALID_PARAM on invalid argument.

function syn_vad_process_frame¶

Process single frame of 16-bit signed PCM audio samples.

SYN_VAD_State syn_vad_process_frame (
    SYN_VAD * vad,
    const int16_t * samples,
    size_t num_samples,
    SYN_VAD_Features * out_features
)

Parameters:

vad VAD instance pointer.
samples Array of 16-bit PCM audio samples.
num_samples Number of samples in frame (should match configured frame_length).
out_features Optional pointer to receive extracted frame metrics (can be NULL).

Returns:

Current smoothed VAD decision (SYN_VAD_STATE_SPEECH or SYN_VAD_STATE_SILENCE).

function syn_vad_reset¶

Reset VAD state counters and restore default noise floor.

SYN_Status syn_vad_reset (
    SYN_VAD * vad
)

Parameters:

vad VAD instance pointer.

Returns:

SYN_OK on success.

function syn_vad_set_sensitivity¶

Adjust VAD sensitivity preset.

SYN_Status syn_vad_set_sensitivity (
    SYN_VAD * vad,
    SYN_VAD_Sensitivity sensitivity
)

Parameters:

vad VAD instance pointer.
sensitivity Sensitivity preset level.

Returns:

SYN_OK on success.

Macro Definition Documentation¶

define SYN_VAD_DEFAULT_ATTACK_FRAMES¶

#define SYN_VAD_DEFAULT_ATTACK_FRAMES `2U`

Consecutive active frames required to trigger

define SYN_VAD_DEFAULT_FRAME_LEN¶

#define SYN_VAD_DEFAULT_FRAME_LEN `160U`

Default 160 samples (10ms @ 16kHz or 20ms @ 8kHz)

define SYN_VAD_DEFAULT_HANGOVER_FRAMES¶

#define SYN_VAD_DEFAULT_HANGOVER_FRAMES `6U`

Hangover frames to sustain active speech

The documentation for this class was generated from the following file src/syntropic/audio/syn_vad.h