Useful ffmpeg commands for newsrooms

ffmpeg_commands.md

Useful ffmpeg commands for newsrooms

Quickly resize, convert, extract audio from videos and edit audio from the command line.

About ffmpeg

A complete, cross-platform solution to record, convert and stream audio and video. https://ffmpeg.org

Installing

Install Homebrew first

$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

Then install ffmpeg with Homebrew

$ brew install ffmpeg

Commands

Resize video down to 640x480

$ ffmpeg -i input.mp4 -s 640x480 output.mp4

Convert to webm

$ ffmpeg -i input.mp4 -c:v libvpx -crf 10 -b:v 1M -c:a libvorbis output.webm

Remove audio from video

$ ffmpeg -i input.mp4 -vcodec copy -an output.mp4

Convert video from mp4 to avi

$ ffmpeg -i input.mp4 output.avi

Extract audio (mp3) from video

$ ffmpeg -i video.mp4 -vn -ab 256 audio.mp3

Adding a fade to black

• make sure you know the frame count and how many frames you want it to last

ffmpeg -i video_file.mp4 -y -vf fade=out:120:30 output_file.mp4

Converting WAV audio file to MP3

ffmpeg -i input.wav -codec:a libmp3lame -qscale:a 2 output.mp3

Save the first frame of video file as jpg

i=1
for frame in *.mov; do
 ffmpeg -i $frame -vframes 1 -f image2 $i.jpg; i=$((i+1))
done

Get the left channel audio and convert to mono

ffmpeg -i input.wav -map_channel 0.0.0 output.wav

Get the right channel audio and convert to stereo MP3

ffmpeg -i input.wav -map_channel 0.0.1 -map_channel 0.0.1 -c:v copy output_right.mp3

Extract the first 30 seconds from the audio file

• -ss indicates the starting time (00:00:00)
• -to indicates the end time (00:00:30)

ffmpeg -i input.mp3 -ss 00:00:00 -to 00:00:30 -c copy output.mp3

To slow down your video, you have to use a multiplier greater than 1:

ffmpeg -i INPUT.mp4 -filter:v "setpts=2.0*PTS" OUTPUT.mp4

Concatenation of files with same codecs:

• Create a file mylist.txt with all the files you want to have concatenated in the following form:

# this is a comment
file '/path/to/file1'
file '/path/to/file2'
file '/path/to/file3'

• Create a mylist.txt file with all the files in its directory with bash:

for f in ./*.mp4; do echo "file '$f'" >> mylist.txt; done

• Command to concatenate files from mylist.txt

ffmpeg -f concat -safe 0 -i mylist.txt -c copy OUTPUT.mp4