Transform

$ ffmpeg -i input.mkv \
    -map_metadata -1 \
    -c:v libx264 -b:v 4096k \
    -c:a libmp3lame -b:a 320k \
    output.mp4

File Format

$ ffmpeg -i input.mkv -c:v copy -c:a copy output.mp4

Extract

$ ffmpeg -i input.mkv -map_metadata -1 -vn -dn -sn -c:a copy output.ac3
$ ffmpeg -i input.mkv -map_metadata -1 -an -dn -sn -c:v copy output.h264
$ ffmpeg -i input.mkv -map_metadata -1 -vn -an -dn -c:s copy output.srt

Assemble

$ ffmpeg -i input.ac3 -i input.h264 \
    -map_metadata -1 \
    -c:v copy -c:a copy \
    output.mkv
$ ffmpeg -i input.mkv -i eng.srt -i chn.srt -i cht.srt \
    -map_metadata -1 \
    -c:v copy -c:a copy -c:s srt -dn \
    -map 0:0 -map 0:1 -map 1:0 -map 2:0 -map 3:0 \
    -metadata:s:s:0 language=eng \
    -metadata:s:s:1 language=chn \
    -metadata:s:s:2 language=cht \
    output.mkv

Capture JPEG Image

$ ffmpeg -i input.mp4 -ss 00:00:05 -r 1 -vframes 1 -an -vcodec mjpeg output.jpg

Split

$ ffmpeg -i input.mp4 -ss 00:00:30 -t 00:00:10 -c copy output.mp4

Resolution

$ ffmpeg -i input.mkv -s 1280x720 -c copy output.mp4

Crop

$ ffmpeg -i input.mp4 -filter:v crop=1920:890:0:95 -c copy output.mp4

Merge

$ echo -ne "file 'part01.flv'\nfile 'part02.flv'\n" > inputs.txt
$ ffmpeg -f concat -i inputs.txt -c copy output.flv