fxgreen's questions

如何将 .m4a 音频文件转换为 .mp3 命令行？（如果可能，质量不会下降）。Ubuntu 16.04LTS 媒体信息：

General
Complete name                            : show.m4a
Format                                   : MPEG-4
Format profile                           : Apple audio with iTunes info
Codec ID                                 : M4A  (M4A /mp42/isom)
File size                                : 55.5 MiB
Duration                                 : 1h 48mn
Overall bit rate mode                    : Variable
Overall bit rate                         : 71.7 Kbps

Audio
ID                                       : 1
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : HE-AAC / LC
Codec ID                                 : 40
Duration                                 : 1h 48mn
Bit rate mode                            : Variable
Bit rate                                 : 72.0 Kbps
Maximum bit rate                         : 93.8 Kbps
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 KHz / 22.05 KHz
Frame rate                               : 21.533 fps (1024 spf)
Compression mode                         : Lossy
Stream size                              : 54.9 MiB (99%)
Writing library                          : Nero AAC codec 1.5.4.0
Encoding settings                        : -q 0.25