These variables are populated from MusicBrainz data for most releases, without any special Picard settings.
Variables that rely on information from the files (e.g.: _bitrate) are only available for use on tracks with attached files, when running scripts manually on files or in the file naming script.
Prior to version 2.5 Picard did not support using file variables in tagging scripts.
Approximate bitrate in kbps.
Bits of data per sample.
Number of audio channels in the file.
The name of the directory containing the file at the point of being loaded into Picard. (since Picard 1.1)
The file’s extension. (since Picard 0.9)
The name of the file without extension. (since Picard 1.1)
Media format of the file (e.g.: MPEG-1 Audio).
The length of the track in format mins:secs.
Number of digitizing samples per second (Hz).