Algorithms#
Supplied Processing Algorithms#
SOF contains several permissively-licensed and royalty-free audio processing algorithms that can be used alongside proprietary processing components to build pipelines.
Algorithm |
Source |
Category |
SIMD |
Key Capabilities |
Status |
|---|---|---|---|---|---|
Volume / Mute |
SOF |
Basic Routing & Level |
ARM, HiFi 3, HiFi 4, HiFi 5, RISCV, Scalar C |
Per-channel linear and log gain curves; Smooth zipper noise attenuation; Zero-overhead bypass when set to 0dB |
Upstream |
Audio Mixer |
SOF |
Basic Routing & Level |
ARM, HiFi 3, HiFi 5, RISCV, Scalar C |
Concurrent playback mixing; Dynamic input stream attachment/detachment; Saturation and clipping protection |
Upstream |
Sample Rate Converter (SRC) |
SOF |
Foundational DSP |
HiFi 2 EP, HiFi 3, HiFi 4, HiFi 5, RISCV, Scalar C |
High SNR polyphase filtering; Low group delay; Multi-channel synchronous resampling |
Upstream |
Asynchronous SRC (ASRC) |
SOF |
Foundational DSP |
HiFi 3, HiFi 5, RISCV, Scalar C |
Farrow polynomial interpolation; Continuous clock drift tracking; Decoupled clock domain bridging |
Upstream |
Audio Demux |
SOF |
Basic Routing & Level |
Scalar C |
Multi-channel stream demultiplexing; Dynamic route splitting; Zero-copy sample extraction |
Upstream |
Audio Mux |
SOF |
Basic Routing & Level |
Scalar C |
Multi-source stream multiplexing; Configurable input channel mapping; Synchronized buffer alignment |
Upstream |
Channel Map / Remap |
SOF |
Basic Routing & Level |
Scalar C |
Arbitrary slot and channel routing; Mono to stereo/surround replication; Channel swap and mute masking |
Upstream |
Tone Generator |
SOF |
Diagnostics & Testing |
RISCV, Scalar C |
Sine wave generation; Configurable frequency and amplitude; Per-channel tone routing |
Upstream |
Parametric Equalizer (EQ FIR) |
SOF |
Audio Enhancement |
ARM, HiFi 2 EP, HiFi 3, HiFi 4, HiFi 5, RISCV, Scalar C |
High-order linear-phase FIR filtering; Speaker and room impulse response correction; Live runtime coefficient updates over IPC |
Upstream |
Parametric Equalizer (EQ IIR) |
SOF |
Audio Enhancement |
ARM, HiFi 2 EP, HiFi 3, HiFi 4, HiFi 5, RISCV, Scalar C |
Cascaded second-order biquad sections; Parametric peak, notch, low/high shelf; Low computational latency |
Upstream |
Dynamic Range Compressor (DRC) |
SOF |
Audio Enhancement |
ARM, HiFi 3, HiFi 4, RISCV, Scalar C |
Speaker excursion and thermal protection; Configurable attack, release, and knee; Peak and RMS signal level detection |
Upstream |
Multiband DRC |
SOF |
Audio Enhancement |
HiFi 3, HiFi 4, RISCV, Scalar C |
Subband crossover splitting; Per-band threshold and ratio controls; Comprehensive speaker protection |
Upstream |
Crossover Filter |
SOF |
Audio Enhancement |
HiFi 3, RISCV, Scalar C |
Linkwitz-Riley 4th order (LR4) splitting; Flat magnitude sum across crossover point; Multi-way woofer, tweeter, and sub routing |
Upstream |
DC Blocker |
SOF |
Audio Enhancement |
ARM, HiFi 3, HiFi 4, RISCV, Scalar C |
Removes DC bias from digital mics and ADCs; Sub-audible rumble attenuation; Near-zero phase distortion in audio band |
Upstream |
Smart Amp Protection |
SOF |
Speaker Protection |
HiFi 3, HiFi 4, Scalar C |
Real-time voice coil temperature estimation; Membrane excursion limiting; Maximizes acoustic output without damage |
Upstream |
Beamformer (TDFB) |
SOF |
Voice & Telephony |
HiFi 2 EP, HiFi 3, HiFi 4, HiFi 5, RISCV, Scalar C |
Multi-mic circular and linear array support; Broadside and endfire steering; Spatial diffuse noise suppression |
Upstream |
WebRTC Echo Cancellation (AEC) |
WebRTC |
Voice & Telephony |
HiFi 3, HiFi 4, VFPU, Scalar C |
Subband adaptive filter convergence; Multi-channel reference loopback alignment; Robust double-talk detection |
Active Development |
WebRTC Mobile AEC (AECM) |
WebRTC |
Voice & Telephony |
HiFi 3, HiFi 4, VFPU, Scalar C |
Fixed-point low-complexity processing; Optimized for earbuds and wearables; Low RAM and cycle footprint |
Active Development |
WebRTC Noise Suppression (NS) |
WebRTC |
Voice & Telephony |
HiFi 3, HiFi 4, VFPU, Scalar C |
Stationary background noise reduction; Configurable aggressiveness levels; Preserves speech formant clarity |
Active Development |
WebRTC Neural NS (NS2 / RNNoise) |
WebRTC |
Voice & Telephony |
HiFi 3, HiFi 4, VFPU, Scalar C |
Recurrent neural network (RNN) inference; Non-stationary transient noise elimination; High speech perceptual quality |
Active Development |
WebRTC Voice Activity Detector (VAD) |
WebRTC |
Voice & Telephony |
HiFi 3, Scalar C |
Multi-band energy likelihood estimation; Sub-frame voice decision gating; Ultra-low power listening states |
Active Development |
WebRTC Automatic Gain Control (AGC) |
WebRTC |
Voice & Telephony |
HiFi 3, HiFi 4, Scalar C |
Dynamic gain adjustment; Saturation prevention limiter; Normalizes quiet and loud speakers |
Active Development |
Key Phrase Buffer (KPB / WoV) |
SOF |
Voice & Telephony |
Scalar C |
Ultra-low power DSP listening mode (D0ix); Zero-latency audio pre-roll buffer playback; Multi-slot capture streaming to host |
Upstream |
microWakeWord (TFLite Micro) |
Voice & Telephony |
HiFi 3, HiFi 4, Scalar C |
On-device neural network keyword spotting; TFLite Micro runtime execution; Low false-reject and false-alarm rates |
Active Development |
|
AAC Decoder |
FFmpeg |
Codecs & Compression |
VFPU, HiFi 3, HiFi 4, HiFi 5, Scalar C |
Vector floating-point hardware acceleration; MPEG-4 AAC-LC and HE-AAC profile support; Direct pipeline integration |
Active Development |
AAC Encoder |
FFmpeg |
Codecs & Compression |
VFPU, HiFi 3, HiFi 4, HiFi 5, Scalar C |
Low-power bitstream encoding; Configurable bitrates and sample rates; Optimized MDCT and psychoacoustic model |
Active Development |
MP3 Decoder |
FFmpeg |
Codecs & Compression |
VFPU, HiFi 3, HiFi 4, HiFi 5, Scalar C |
Hardware VFPU SIMD acceleration; High-throughput low-overhead DSP execution; Full bit reservoir and Huffman decoding |
Active Development |
MP3 Encoder |
FFmpeg |
Codecs & Compression |
VFPU, HiFi 3, HiFi 4, Scalar C |
Low-complexity fixed-point encoding; Efficient subband analysis filterbank; Standard MPEG-1 Layer III bitstream generation |
Active Development |
FLAC Decoder |
FFmpeg |
Codecs & Compression |
VFPU, HiFi 3, HiFi 4, Scalar C |
Lossless 16/24-bit audio decompression; Fast linear prediction decoding; Zero fidelity loss playback |
Active Development |
Opus Decoder |
FFmpeg |
Codecs & Compression |
VFPU, HiFi 3, HiFi 4, Scalar C |
SILK speech and CELT music mode support; Sub-20ms algorithmic latency; Dynamic bitrate and bandwidth adaptation |
Active Development |
Vorbis Decoder |
FFmpeg |
Codecs & Compression |
VFPU, HiFi 3, HiFi 4, Scalar C |
General-purpose variable bitrate decompression; Vector quantization floor decoding; Low memory footprint |
Active Development |
Steam Audio Spatializer |
Steam Audio |
Spatial Audio |
VFPU, HiFi 4, HiFi 5, Scalar C |
Spherical 3D sound positioning; Convolution-based HRTF binaural rendering; Dynamic listener and source orientation |
Active Development |
Real-Time Probes & Telemetry |
SOF |
Diagnostics & Tools |
Scalar C |
Direct probe DMA streaming over TCP port 9999; Zero overhead when probe taps are inactive; Multi-point simultaneous stream tapping |
Upstream |
Note
For detailed algorithm implementation guides, filter tuning workflows, and design tools, consult the Algorithm Specific Information section in Developer Guides.