ffmpeg -loglevel values: quiet, error, warning, info, debug

-loglevel (alias -v) sets how much ffmpeg, ffprobe and ffplay print, by name or by number. The default is info (32). In scripts, -hide_banner -loglevel error prints only errors, and -loglevel quiet prints nothing at all.

Levels

Compare the output

ffmpeg -hide_banner -loglevel error -f lavfi -i testsrc=duration=1 -frames:v 1 -y frame.png
echo "lines with -loglevel error: $(ffmpeg -hide_banner -loglevel error -f lavfi -i testsrc=duration=1 -frames:v 1 -y frame.png 2>&1 | wc -l)"
echo "lines with -loglevel info:  $(ffmpeg -hide_banner -loglevel info -f lavfi -i testsrc=duration=1 -frames:v 1 -y frame.png 2>&1 | wc -l)"

lines with -loglevel error: 0
lines with -loglevel info:  16

Flags

Prefix the level with flags to change the format:

ffmpeg -loglevel repeat+level+verbose -i input.mp4 output.mp4

level prefixes each line with its level ([error], [info]), repeat stops collapsing repeated lines. -report additionally writes a full debug log to a file named ffmpeg-YYYYMMDD-HHMMSS.log.