| 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 | ||
| timezone | ||
| 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) | ||
| channels | ||
| 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. | |