SpecBlender

A Rust-based spectral sound processing toolkit using STFT. This contains some algorithms from spec_utils.py. Compared to the Python version, the Rust implementation runs faster. For example, min-mag runs three times faster (on a Ryzen 7).

Requirements

FFmpeg must be available in PATH

Usage

specblender [ALGORITHM] input1.wav input2.wav output.wav [OPTIONS]

Algorithms

min-mag (Default)

Minimum magnitude spectral blending. Merges two audio files by selecting the quieter spectral components at each frequency bin.

max-mag

Maximum magnitude spectral blending. Selects the louder spectral components at each frequency bin.

sub

Spectral subtraction (input1 - input2). It works like an Invert_p.

copy-phase

Copies phase information from input1 to the magnitude of input2.

Options

Option	Description
--mono	Process mono (average of both channels), export mono output
--mono-post	Process stereo, then mix to mono, export mono output
--n_fft=N	FFT window size (default: 2048, range: 32-65536)
--hop=H	Hop length in samples (default: 512, must be ≤ n_fft)
--window=TYPE	Window function: hann or hamming (default: hann)
--stft=MODE	STFT processing mode: single or multi (default: single)
--streaming=MODE	Streaming mode: off, on, auto (default: auto)
--pcm_type=TYPE	PCM output format: pcm24 or float32 (default: float32)
--phase=SOURCE	Phase source control: auto, input1, input2 (default: auto)

STFT Modes

• single (default) - Standard STFT processing
• multi - Multi-resolution processing:
  • Low frequencies: FFT=4096 for better frequency resolution
  • High frequencies: FFT=1024 for better time resolution
  • Intelligent frequency band blending via FFmpeg filters

Streaming Mode

• --streaming=off - Process entire file in memory (more memory usage)
• --streaming=on - Process in chunks (constant memory usage)
• --streaming=auto - Automatically use streaming for files longer than 10 minutes

PCM Output Format

• --pcm_type=float32 - 32-bit floating point WAV (default, maximum quality)
• --pcm_type=pcm24 - 24-bit integer PCM WAV (smaller file size)

Phase Control

• auto (default) - Use phase from signal with appropriate magnitude (algorithm-dependent)
• input1 - Always use phase from first input file
• input2 - Always use phase from second input file

Building from Source

git clone https://github.com/aufr33/specblender
cd specblender
cargo build --release