aporee metadata notes
sound title
location title
location address provided by geonames.org, Google
latitude WGS84 latitude
longitude WGS84 longitude
elevation provided by SRTM, GTOPO30, Google
recording artist
recording date
description provided by the artist
sound metadata xk: a sample, xk-1: the previous sample
file url
file size (bytes)
bitrate (kbit/s)
sample frequency (Hz)
length (sec)
length (min)
# samples number of audio samples
max amplitude the maximum sample value in the audio
min amplitude the maximum sample value in the audio
midline amplitude ½ min amp + ½ max amp
mean amplitude ¹/nΣxk the average of each sample in the audio. If this figure is non-zero, then it indicates the presence of a DC offset
mean norm ¹/nΣ│xk│ the average of the absolute value of each sample in the audio.
RMS amplitude √(¹/nΣxk²) standard RMS (root mean square) level measured in dBFS, The level of a DC signal that would have the same power as the audio's average power.
max delta max(│xk-xk-1│) max level difference between tow consecutive samples
min delta min(│xk-xk-1│) min level difference between tow consecutive samples
mean delta ¹/n-1Σ│xk-xk-1│
RMS delta √(¹/n-1Σ(xk-xk-1)²)
rough frequency (Hz) kind of mean frequency through all samples. todo...
volume adjustment factor of amplification needed in order to get max volume without clipping (0dBFS)
DC offset center of the recording waveform not at 0, but at a higher or lower value. The effect of a DC offset is reduced headroom and hence volume.
crest factor Crest factor is the standard ratio of peak to RMS level (note: not in dB). The crest factor indicates how extreme the peaks are in a waveform.
flat factor Flat factor is a measure of the 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 level standard peak level measured in dBFS
peak count number of occasions (not the number of samples) that the signal attained either Min level, or Max level.
clipping a good guess whether this sound is clipping (i.e. cut at 0dBFS) or not. Clipping is bad and to avoid under any circumstances.

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