原來在 Mac 底下也有檢視音樂檔案資訊的功能，指令是 afinfo 。
我在 iTunes Store 買了二本貓的歌，用 afinfo 來看可以看到詳細資訊：
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14:40:48 [roga@kitchen ~/Music/iTunes/iTunes Media/Music/UrbanCat/光亮徬徨的閃耀年紀] $ afinfo 03\ 青青黃黃的.m4a File: 03 青青黃黃的.m4a File type ID: m4af Num Tracks: 1 ---- Data format: 2 ch, 44100 Hz, 'aac ' (0x00000000) 0 bits/channel, 0 bytes/packet, 1024 frames/packet, 0 bytes/frame Channel layout: Stereo (L R) estimated duration: 305.920000 sec audio bytes: 10123309 audio packets: 13177 bit rate: 264688 bits per second packet size upper bound: 1302 maximum packet size: 1302 audio data file offset: 613231 optimized audio 13491072 valid frames + 2112 priming + 64 remainder = 13493248 source bit depth: I24 format list: [ 0] format: 2 ch, 44100 Hz, 'aac ' (0x00000000) 0 bits/channel, 0 bytes/packet, 1024 frames/packet, 0 bytes/frame Channel layout: Stereo (L R) Loudness Info: sound check info : sc ave perceived power coeff : "1599 1549" sc max perceived power coeff : "18326 18673" sc peak amplitude msec : "281124 112524" sc max perceived power msec : "221472 221472" sc peak amplitude : "31910 32129" media kind : "Music" main loudness parameters : aa itu true peak : -0.128906 aa ebu top of loudness range : -9.25 aa ebu loudness range : 12.5 aa itu loudness : -12.5 aa ebu max momentary loudness : -8 aa ebu max short-term loudness : -9 sound check volume normalization gain: -3.50 dB ---- |