Some examples I use.

Most of the time I just use—

ffmpeg -i input.ext output.ext

—and it usually works fine leaving it to just use defaults.

For doing a whole directory I use this one-liner I got from Stack Exchange.

for i in *.ext; do ffmpeg -i "$i" "${i%.*}.ext"; done

You can use the wildcard * in the file extension to, so if you've got a mix of .mkv and .mp4 files from Youtube you can do. say:

for i in *.m*; do ffmpeg -i "$i" "${i%.*}.ogv"; done

If you want to put the new videos into a subdirectory, first create it, then simply add it to the output part:

for i in *.ext; do ffmpeg -i "$i" "directory/${i%.*}.ext"; done

For converting a directory of .FLAC files to .MP3. [-qscale:a 0|-b:a 320k] is your choice between VBR with the best quality (0) or a CBR of 320k. VBR is generally just as good, though sometimes you need CBR.

for a in ./*.flac; do ffmpeg -i "$a" [-qscale:a 0|-b:a 320k] "${a[@]/%flac/mp3}"; done

The main thing I use FFmpeg for is just stitching videos together. I make a list of the files inside a text document, each line looks like this:—

file '[file location]'

—then point FFmpeg at that and give the command and it runs through them all. Nice and easy.

ffmpeg -f concat -safe 0 -i "inputfile.txt" -c copy "inputfile.ext"

※ Todo: use bash to generate the file list

Add -an to your command.

Rotate 90°.

ffmpeg -i inputfile.ext -vf "transpose=1" outputfile.ext

You can pretty easily make a video file smaller. The only caveat is that if you don't want to re-encode you're limited by where keyframes are placed.

ffmpeg -i inputfile.ext -ss HH:MM:SS -to HH:MM:SS -c copy outputfile.ext

• -ss is the point you want it to start
• -to is the point you want it to end
• -t is the length you want it to run from the start time
• Instead of using the format HH:MM:SS you can just give a number of seconds.
  • You can also add milliseconds to either of those formats.
• Leaving out the -ss or -to|t will use the file's existing start or end time.
• If you leave out the -c copy it will re-encode the video

Slow, but compresses better:

-preset veryslow

Scales 50%

ffmpeg -i "inputfile.ext" -vf "scale=iw/2:ih/2" "outputfile.ext"

Scales to set pixel dimensions (replace 'width' and 'height'):

ffmpeg -i "inputfile.ext" -vf scale=width:height "outputfile".ext

• https://trac.ffmpeg.org/wiki/Scaling

• www.ffmpeg.org