Slowed down audio (audio_speed < 1) leads to inaccurate timestamps

[Josef-Haupt]

Reproduction code:

import birdnet

target = (
  r"<path_to_analyzer>\birdnet_analyzer\example\soundscape.wav"
)
top_k = 1
batch_size = 1
prefetch_ratio = 3
overlap_duration_s = 1
bandpass_fmin = 0
bandpass_fmax = 15000
sigmoid_sensitivity = 1.0
speed = 0.1
default_confidence_threshold = 0
custom_species_list = None
progress_callback = None
show_stats = "progress"
n_workers = None
n_producers = 1
apply_sigmoid = True

if __name__ == "__main__":
  model = birdnet.load(
    "acoustic",
    "2.4",
    "tf",
  )
  result = model.predict(
    target,
    top_k=top_k,
    batch_size=batch_size,
    prefetch_ratio=prefetch_ratio,
    overlap_duration_s=overlap_duration_s,
    bandpass_fmin=bandpass_fmin,
    bandpass_fmax=bandpass_fmax,
    sigmoid_sensitivity=sigmoid_sensitivity,
    speed=speed,
    default_confidence_threshold=default_confidence_threshold,
    custom_species_list=custom_species_list,
    progress_callback=progress_callback,
    show_stats=show_stats,
    n_workers=n_workers,
    n_producers=n_producers,
    apply_sigmoid=apply_sigmoid,
  )
  df = result.to_dataframe()

  df.to_csv("output.csv", index=False)

Expected output (head):

input,start_time,end_time,species_name,confidence
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.0,0.3,Engine_Engine,0.021369556
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.2,0.5,Otus rufescens_Reddish Scops-Owl,0.16111241
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.4,0.7,Ciccaba virgata_Mottled Owl,0.15136504
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.6,0.9,Engine_Engine,0.019372134
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.8,1.1,Engine_Engine,0.011949962

Actual output (head):

input,start_time,end_time,species_name,confidence
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.0,0.2998,Engine_Engine,0.021369556
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.2,0.4998,Otus rufescens_Reddish Scops-Owl,0.16111241
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.4,0.6997,Ciccaba virgata_Mottled Owl,0.15136504
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.5996,0.8994,Engine_Engine,0.019372134
C:\Users\johau\tuc\BirdNET-Analyzer-clone\birdnet_analyzer\example\soundscape.wav,0.8,1.1,Engine_Engine,0.011949962

[Josef-Haupt]

Doesn't seem to be an issue with Perch though.