Spectrogram

Features

• Multi-format audio support (M4A, MP3, WAV, etc.) via FFmpeg
• Advanced frequency scales (Linear, Log, Mel, Bark, ERB)
• Multiple color schemes (Gray, Inverted Gray, Heat, Inferno)
• Intensity mapping options (Linear, Log, Power, Sqrt, Sigmoid)
• Window functions (Hanning, Hamming, Blackman, Rectangular)
• Configurable FFT parameters (FFT size, hop size)
• Long audio handling (automatic splitting and stitching)
• Metadata extraction (timestamps, location, device info)

Installation

npm install

Usage

# Basic usage
npm run start "audio-file.m4a"

# With options
npm run start "audio-file.m4a" -- --max-freq 8000 --color heat --scale mel

Key Options

• --max-freq <hz> - Maximum frequency to display
• --min-freq <hz> - Minimum frequency to display
• --color <preset> - Color scheme (gray, invgray, heat, inferno)
• --scale <type> - Frequency scale (linear, log, mel, bark, erb)
• --mapping <type> - Intensity mapping (linear, log, power, sqrt, sigmoid)
• --window <type> - Window function (hanning, hamming, blackman, rectangular)
• --fft-size <size> - FFT size in samples (default: 2048)
• --hop-size <size> - Hop size in samples (default: 512)
• --height <height> - Spectrogram height in pixels (default: 768)
• --pixels-per-second <pps> - Pixels per second for width (default: 96)
• --min-db <db> - Minimum dB for color mapping (default: auto)
• --max-db <db> - Maximum dB for color mapping (default: auto)
• -o, --output <file> - Output PNG file path

Configuration

The src/constants.ts file contains all default parameters and configuration values:

• DB_CONSTANTS: Decibel ranges and thresholds for visualization
• FFT_CONSTANTS: FFT analysis parameters (size, hop size)
• WINDOW_CONSTANTS: Window function coefficients
• RENDERING_CONSTANTS: Canvas and rendering limits
• DEFAULTS: Default values for all command-line options
• VALID_OPTIONS: Available choices for enum-based options

Modify these constants to customize default behavior without changing the source code.

Output

• filename.png - Single spectrogram (short audio)
• filename_overview.png - Overview of entire audio
• filename_part1.png, filename_part2.png - Detailed parts (long audio)
• filename_stitched.png - Combined detailed parts
• filename.meta.json - Extracted audio metadata