Main mixer structure for multi-source audio processing. More...

#include <lib/audio/mixer.h>

Data Fields
int	num_sources
	Current number of active audio sources.

int	max_sources
	Maximum number of sources (allocated array sizes)

int	sample_rate
	Sample rate in Hz (e.g., 44100)

audio_ring_buffer_t **	source_buffers
	Array of pointers to client audio ring buffers.

uint32_t *	source_ids
	Array of client IDs (one per source slot)

bool *	source_active
	Array of active flags (true if source is active)

uint64_t	active_sources_mask
	Bitset of active sources (bit i = source i is active, O(1) iteration)

uint8_t	source_id_to_index [256]
	Hash table mapping client_id → mixer source index (uses hash function for 32-bit IDs)

uint32_t	source_id_at_hash [256]
	Client IDs stored at each hash index for collision detection.

rwlock_t	source_lock
	Reader-writer lock protecting source arrays and bitset.

float	crowd_alpha
	Crowd scaling exponent (typically 0.5 for sqrt scaling)

float	base_gain
	Base gain before crowd scaling is applied.

ducking_t	ducking
	Ducking system (active speaker detection and attenuation)

compressor_t	compressor
	Compressor (dynamic range compression)

float *	mix_buffer
	Temporary buffer for mixing operations (pre-allocated)

Detailed Description

Main mixer structure for multi-source audio processing.

Manages multiple audio sources (clients) and processes them through a professional audio processing pipeline. Supports up to MIXER_MAX_SOURCES simultaneous sources with automatic crowd scaling and active speaker detection.

MIXER ARCHITECTURE:

Source Management: Array of audio ring buffers, one per client
Optimized Lookup: Bitset + hash table for O(1) source exclusion
Thread Safety: Reader-writer locks for concurrent access
Crowd Scaling: Automatic volume adjustment based on participant count
Audio Processing: Ducking, compression, noise gate, high-pass filter

PERFORMANCE OPTIMIZATIONS:

Bitset-based active source tracking (O(1) exclusion)
Hash table for client ID to mixer index mapping
Pre-allocated mix buffer (no allocations in hot path)
Reader-writer locks for concurrent reads

Note

Each source is indexed by position in arrays (0 to max_sources-1). Client IDs are mapped to indices via source_id_to_index hash table.

Active sources are tracked in two ways:

source_active[] array for per-source status
active_sources_mask bitset for O(1) iteration exclusion

Warning: Source arrays must be locked (read or write) during iteration to prevent concurrent modifications.

Definition at line 325 of file mixer.h.

The documentation for this struct was generated from the following file:

mixer.h

Data Fields

Detailed Description