多个片段合并成一个：
ffmpeg -i a.flv \
-vf "select='between(t,0,34)+between(t,170,177)+between(t,400,465)+between(t,475,603)',
setpts=N/FRAME_RATE/TB" \
-af "aselect='between(t,0,34)+between(t,170,177)+between(t,400,465)+between(t,475,603)',
asetpts=N/SR/TB" out.flv
webm to mp3
FILE="the-file-you-want-to-process.webm";
ffmpeg -i "${FILE}" -vn -ab 128k -ar 44100 -y "${FILE%.webm}.mp3";
m3u8 to local file
ffmpeg -i "http://example.com/chunklist.m3u8" -codec copy file.mp4
cut head
ffmpeg -ss 00:00:58 -i 1.mp4 -c copy 2.mp4
