batdetect2/docs/source/how_to/configure-spectrogram-preprocessing.md

How to configure spectrogram preprocessing

Use this guide to set STFT, frequency range, and spectrogram transforms.

1) Configure STFT and frequency range

preprocess:
  stft:
    window_duration: 0.002
    window_overlap: 0.75
    window_fn: hann
  frequencies:
    min_freq: 10000
    max_freq: 120000

2) Configure spectrogram transforms

spectrogram_transforms are applied in order.

preprocess:
  spectrogram_transforms:
    - name: pcen
      time_constant: 0.4
      gain: 0.98
      bias: 2.0
      power: 0.5
    - name: spectral_mean_subtraction
    - name: scale_amplitude
      scale: db

Common built-ins:

• pcen
• spectral_mean_subtraction
• scale_amplitude (db or power)
• peak_normalize

3) Configure output size

preprocess:
  size:
    height: 128
    resize_factor: 0.5

4) Keep train and inference settings aligned

Use the same preprocessing setup for training and prediction whenever possible. Large mismatches can degrade model performance.

Related pages

• Why consistency matters: {doc}../explanation/preprocessing-consistency
• Preprocessing config reference: {doc}../reference/preprocessing-config