5 name => '<abbr title="MPEG-1 Audio Layer III">MP3</abbr>',
20 name => '<abbr title="Advanced Audio Coding">AAC</abbr>',
25 name => '<abbr title="Adaptive Transform Acoustic Coding">ATRAC</abbr>',
32 children => [qw( quality limits royalties support )],
35 name => 'compression quality',
36 children => [qw( quality_music quality_speech quality_ll )],
66 children => [qw( channels bitrate latency peeling )],
72 mp3 => [3, 6, 'stereo, extended to upto 5.1'],
78 name => 'bitrate peeling',
80 vorbis => [3, undef, 'yes but "unusable" quality'],
87 name => 'frame size (ms)',
89 mp3 => [3, 26, 'typical version and layer has 1152 samples at 44kHz'],
94 name => 'minimal bitrate',
102 mp3 => [5, undef, 'expired'],
104 opus => [4, undef, 'open and free design'],
105 atrac => [2, undef, 'proprietary, but the original patents have expired'],