通过 ffmpeg 获取 媒体 播放时长
./ffmpeg-linux64-v3.3.1 -i /tmp/mp30001.mp3
ffmpeg version N-86111-ga441aa90e8-static http://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 5.4.1 (Debian 5.4.1-8) 20170304
configuration: --enable-gpl --enable-version3 --enable-static --disable-debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-5 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-gray --enable-libass --enable-libfreetype --enable-libfribidi --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzimg
libavutil 55. 63.100 / 55. 63.100
libavcodec 57. 96.101 / 57. 96.101
libavformat 57. 72.101 / 57. 72.101
libavdevice 57. 7.100 / 57. 7.100
libavfilter 6. 89.101 / 6. 89.101
libswscale 4. 7.101 / 4. 7.101
libswresample 2. 8.100 / 2. 8.100
libpostproc 54. 6.100 / 54. 6.100
[0;35m[mp3 @ 0x4cd9ea0] [0m [0;33mEstimating duration from bitrate, this may be inaccurate
[0mInput #0, mp3, from '/tmp/mp30001.mp3':
Duration: 00:00:12.17, start: 0.000000, bitrate: 16 kb/s
Stream #0:0: Audio: mp3, 16000 Hz, mono, s16p, 16 kb/s
[4;31mAt least one output file must be specified