Crop image size in a video

ffmpeg -i input.mp4  -filter:v "crop=640:480:200:150" -y -v error output.mp4
# -filter:v mean a filter is applied to the video stream. crop=640:480:200:150 means crop a rect of size w:h:x:y
# if -y specified, overwrite existed file
# -v control the verbosity. 
# can be "quiet", "panic", "fatal", "error", "warning", "info", "verbose", "debug", "trace"

Probe format and realted information of a video

ffprobe input.mp4 -v info -hide_banner
# -hide_banner: not print version and configuration of ffprobe
  • Show duration:
ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 input.mp4
# -show_entries entry_list  show a set of specified entries
# -of format alias for -print_format format, 
# set the output printing format default, compact, csv, flat, ini, json, xml
  • Show number of stream
ffprobe -show_entries format=nb_streams -v 0 -of compact=p=0:nk=1 input.mp4
  • Show bitrate:
# for video, 0 is index of the stream
ffprobe  -v error -select_streams v:0 -show_entries stream=bit_rate -of default=noprint_wrappers=1:nokey=1 input.mp4
# for audio, 0 is index of the stream
ffprobe  -v error -select_streams a:0 -show_entries stream=bit_rate -of default=noprint_wrappers=1:nokey=1 input.mp4
  • A more complicated example 
    # https://superuser.com/questions/891665/ffprobe-show-entries-with-an-entry-name-that-uses-a-semicolon
ffprobe -v error -show_entries stream_tags=rotate:format=size,duration:stream=codec_name,bit_rate -of default=noprint_wrappers=1 input.mp4
# print as key value pair

Slice a video

ffmpeg -ss 00:00:30.0 -i input.mp4 -c copy -t 00:00:10.0 output.mp4
# -ss: start time
# -t: duration (-to also works, which accepts stop time)

Convert MP3 to MP4 by adding a static image

ffmpeg -loop 1 -i input.jpg -i input.mp3 -c:a copy -c:v libx264 -vf "pad=ceil(iw/2)*2:ceil(ih/2)*2" -pix_fmt yuvj420p -y -shortest output.mp4
# -vf is an alias for -filter:v
# -vf "pad=ceil(iw/2)*2:ceil(ih/2)*2": pad the image to make it dividable by 2
# -pix_fmt yuvj420p: some player can't parse the default pixcel format

Concatenate multiple videos

for i in $(ls | grep '.mp3' );do echo "file $PWD/$i";done > filelist.txt
ffmpeg -f concat -safe 0 -i filelist.txt -c copy concatenated.mp3

Extract images from video

mkdir -p  frames
ffmpeg -i input.mp4 -vf fps=1 frames/out-%03d.jpg
# fps=1: extract 1 image per second

Extract audio from video

ffmpeg -i input.mp4 -vn output.mp3

mp4 to gih

#!/bin/bash 
ffmpeg -i ${mp4} -r 5 -vf scale=256:-1 ${mp4%.*}.gif