Display time domain statistical information about the audio channels. Statistics are calculated and displayed for each audio channel and, where applicable, an overall figure is also given.

It accepts the following option:

length

Short window length in seconds, used for peak and trough RMS measurement. Default is 0.05 (50 milliseconds). Allowed range is [0.01 - 10].

metadata

Set metadata injection. All the metadata keys are prefixed with lavfi.astats.X, where X is channel number starting from 1 or string Overall. Default is disabled.

Available keys for each channel are: DC_offset Min_level Max_level Min_difference Max_difference Mean_difference RMS_difference Peak_level RMS_peak RMS_trough Crest_factor Flat_factor Peak_count Noise_floor Noise_floor_count Bit_depth Dynamic_range Zero_crossings Zero_crossings_rate Number_of_NaNs Number_of_Infs Number_of_denormals

and for Overall: DC_offset Min_level Max_level Min_difference Max_difference Mean_difference RMS_difference Peak_level RMS_level RMS_peak RMS_trough Flat_factor Peak_count Noise_floor Noise_floor_count Bit_depth Number_of_samples Number_of_NaNs Number_of_Infs Number_of_denormals

For example full key look like this lavfi.astats.1.DC_offset or this lavfi.astats.Overall.Peak_count.

For description what each key means read below.

reset

Set number of frame after which stats are going to be recalculated. Default is disabled.

measure_perchannel

Select the entries which need to be measured per channel. The metadata keys can be used as flags, default is all which measures everything. none disables all per channel measurement.

measure_overall

Select the entries which need to be measured overall. The metadata keys can be used as flags, default is all which measures everything. none disables all overall measurement.

A description of each shown parameter follows:

DC offset

Mean amplitude displacement from zero.

Min level

Minimal sample level.

Max level

Maximal sample level.

Min difference

Minimal difference between two consecutive samples.

Max difference

Maximal difference between two consecutive samples.

Mean difference

Mean difference between two consecutive samples. The average of each difference between two consecutive samples.

RMS difference

Root Mean Square difference between two consecutive samples.

Peak level dB, RMS level dB

Standard peak and RMS level measured in dBFS.

RMS peak dB, RMS trough dB

Peak and trough values for RMS level measured over a short window.

Crest factor

Standard ratio of peak to RMS level (note: not in dB).

Flat factor

Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels (i.e. either Min level or Max level).

Peak count

Number of occasions (not the number of samples) that the signal attained either Min level or Max level.

Noise floor dB

Minimum local peak measured in dBFS over a short window.

Noise floor count

Number of occasions (not the number of samples) that the signal attained Noise floor.

Bit depth

Overall bit depth of audio. Number of bits used for each sample.

Dynamic range

Measured dynamic range of audio in dB.

Zero crossings

Number of points where the waveform crosses the zero level axis.

Zero crossings rate

Rate of Zero crossings and number of audio samples.