For videos with sound, save information about audio volume levels in the
media asset's metadata. These values are stored:
* FFmpeg:AudioPeakLoudness The peak loudness of the audio track, from 0.0 (silent) to 1.0 (max volume)
* FFmpeg:AudioAverageLoudness The average loudness of the audio track, from 0.0 (silent) to 1.0 (max volume).
* FFmpeg:AudioLoudnessRange The difference between the quietest and loudest sounds in the audio track (in decibels).
* FFmpeg:AudioSilencePercentage The percentage of the video that is silent (1.0 is completely silent, 0.5 is 50% silence, 0.0 is no silence).
These values are calculated based on the EBU R 128 standard, using the ffmpeg command below:
ffmpeg -i file.mp4 -af silencedetect=duration=0.05:noise=0.0001,ebur128=metadata=1:peak=true:dualmono=true -f null /dev/null
See the links below for details:
* https://en.wikipedia.org/wiki/EBU_R_128
* https://www.ffmpeg.org/ffmpeg-filters.html#ebur128-1
* https://tech.ebu.ch/loudness
* https://tech.ebu.ch/docs/tech/tech3341.pdf
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