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 - 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: Bit_depthCrest_factorDC_offsetDynamic_rangeEntropyFlat_factorMax_differenceMax_levelMean_differenceMin_differenceMin_levelNoise_floorNoise_floor_countNumber_of_InfsNumber_of_NaNsNumber_of_denormalsPeak_countPeak_levelRMS_differenceRMS_peakRMS_troughZero_crossingsZero_crossings_rate

and for Overall: Bit_depthDC_offsetEntropyFlat_factorMax_differenceMax_levelMean_differenceMin_differenceMin_levelNoise_floorNoise_floor_countNumber_of_InfsNumber_of_NaNsNumber_of_denormalsNumber_of_samplesPeak_countPeak_levelRMS_differenceRMS_levelRMS_peakRMS_trough

For example, a full key looks like lavfi.astats.1.DC_offset or lavfi.astats.Overall.Peak_count.

Read below for the description of the keys.

reset

Set the number of frames over which cumulative stats are calculated before being reset. Default is disabled.

measure_perchannel

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

A description of the measure keys follow:

none

no measures

all

all measures

Bit_depth

overall bit depth of audio, i.e. number of bits used for each sample

Crest_factor

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

DC_offset

mean amplitude displacement from zero

Dynamic_range

measured dynamic range of audio in dB

Entropy

entropy measured across whole audio, entropy of value near 1.0 is typically measured for white noise

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)

Max_difference

maximal difference between two consecutive samples

Max_level

maximal sample level

Mean_difference

mean difference between two consecutive samples, i.e. the average of each difference between two consecutive samples

Min_difference

minimal difference between two consecutive samples

Min_level

minimal sample level

Noise_floor

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

Number_of_Infs

number of samples with an infinite value

Number_of_NaNs

number of samples with a NaN (not a number) value

Number_of_denormals

number of samples with a subnormal value

Number_of_samples

number of samples

Peak_count

number of occasions (not the number of samples) that the signal attained either Min_level or Max_level

Peak_level

standard peak level measured in dBFS

RMS_difference

Root Mean Square difference between two consecutive samples

RMS_level

standard RMS level measured in dBFS

RMS_peak, RMS_trough

peak and trough values for RMS level measured over a short window, measured in dBFS.

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