Vad

class torchaudio.transforms.Vad(sample_rate: int, trigger_level: float = 7.0, trigger_time: float = 0.25, search_time: float = 1.0, allowed_gap: float = 0.25, pre_trigger_time: float = 0.0, boot_time: float = 0.35, noise_up_time: float = 0.1, noise_down_time: float = 0.01, noise_reduction_amount: float = 1.35, measure_freq: float = 20.0, measure_duration: Optional[float] = None, measure_smooth_time: float = 0.4, hp_filter_freq: float = 50.0, lp_filter_freq: float = 6000.0, hp_lifter_freq: float = 150.0, lp_lifter_freq: float = 2000.0)

Voice Activity Detector. Similar to SoX implementation.

Attempts to trim silence and quiet background sounds from the ends of recordings of speech. The algorithm currently uses a simple cepstral power measurement to detect voice, so may be fooled by other things, especially music.

The effect can trim only from the front of the audio, so in order to trim from the back, the reverse effect must also be used.

Parameters:

• sample_rate (int) – Sample rate of audio signal.

• trigger_level (float, optional) – The measurement level used to trigger activity detection. This may need to be changed depending on the noise level, signal level, and other characteristics of the input audio. (Default: 7.0)

• trigger_time (float, optional) – The time constant (in seconds) used to help ignore short bursts of sound. (Default: 0.25)

• search_time (float, optional) – The amount of audio (in seconds) to search for quieter/shorter bursts of audio to include prior to the detected trigger point. (Default: 1.0)

• allowed_gap (float, optional) – The allowed gap (in seconds) between quiteter/shorter bursts of audio to include prior to the detected trigger point. (Default: 0.25)

• pre_trigger_time (float, optional) – The amount of audio (in seconds) to preserve before the trigger point and any found quieter/shorter bursts. (Default: 0.0)

• boot_time (float, optional) The algorithm (python:internally) – estimation/reduction in order to detect the start of the wanted audio. This option sets the time for the initial noise estimate. (Default: 0.35)

• noise_up_time (float, optional) – for when the noise level is increasing. (Default: 0.1)

• noise_down_time (float, optional) – for when the noise level is decreasing. (Default: 0.01)

• noise_reduction_amount (float, optional) – the detection algorithm (e.g. 0, 0.5, …). (Default: 1.35)

• measure_freq (float, optional) – processing/measurements. (Default: 20.0)

• measure_duration – (float or None, optional) Measurement duration. (Default: Twice the measurement period; i.e. with overlap.)

• measure_smooth_time (float, optional) – spectral measurements. (Default: 0.4)

• hp_filter_freq (float, optional) – at the input to the detector algorithm. (Default: 50.0)

• lp_filter_freq (float, optional) – at the input to the detector algorithm. (Default: 6000.0)

• hp_lifter_freq (float, optional) – in the detector algorithm. (Default: 150.0)

• lp_lifter_freq (float, optional) – in the detector algorithm. (Default: 2000.0)

Example

>>> waveform, sample_rate = torchaudio.load("test.wav", normalize=True)
>>> waveform_reversed, sample_rate = apply_effects_tensor(waveform, sample_rate, [["reverse"]])
>>> transform = transforms.Vad(sample_rate=sample_rate, trigger_level=7.5)
>>> waveform_reversed_front_trim = transform(waveform_reversed)
>>> waveform_end_trim, sample_rate = apply_effects_tensor(
>>>     waveform_reversed_front_trim, sample_rate, [["reverse"]]
>>> )

Reference:

• http://sox.sourceforge.net/sox.html

forward(waveform: Tensor) → Tensor

Parameters:

waveform (Tensor) – Tensor of audio of dimension (channels, time) or (time) Tensor of shape (channels, time) is treated as a multi-channel recording of the same event and the resulting output will be trimmed to the earliest voice activity in any channel.