ffmpeg tutorials
Table of Contents
- 1. Introduction
- 2. Installation
- 3. Live streaming with ffmpeg
- 4. Record audio with ffmpeg
- 5. Screen recording with ffmpeg
- 6. Concatenate multiple files
- 7. Merge video with audio and keeping the shortest duration (from video)
- 8. You can also split video.
- 9. Extract single frame from a video
- 10. You can also reduce file size drastically using this command.
- 11. Reduce the size of all the videos in a directory.
- 12. Recursively go inside directories and execute a command on them
- 13. Find duration of videos in the directory
- 14. Blur
1 Introduction
ffmpeg is a great piece of software. It is a cross platform utility to modify audio and video. It can do lot of wonderful things like editing videos, encoding them and live streaming as well. In this post I want to share whatever little I know and have been exploring.
Installing it is easy. Just check your package manager but on Arch linux you can do sudo pacman -S ffmpeg and it should install it.
2 Installation
2.1 CentOS 8
sudo rpm --import http://li.nux.ro/download/nux/RPM-GPG-KEY-nux.ro sudo rpm -Uvh http://li.nux.ro/download/nux/dextop/el7/x86_64/nux-dextop-release-0-1.el7.nux.noarch.rpm sudo yum repolist sudo dnf install ffmpeg sudo yum-config-manager --enable powertools
3 Live streaming with ffmpeg
I recently made a video explain how to use ffmpeg to live stream from local computer to YouTube using nothing but shell scripts.
Check the video here.
4 Record audio with ffmpeg
5 Screen recording with ffmpeg
ffmpeg -video_size 1368x768 -framerate 25 -f x11grab -i :0.0+0,30 -f pulse -i default -ac 2 rec-01.mp4
6 Concatenate multiple files
6.1 Create file.txt for the concatenate to work
for f in *.mp4 ; do echo "file '${f}'" >> file.txt; done;
6.2 While concatenating multiple videos
ffmpeg -safe 0 -f concat -i file.txt -vcodec copy output.mp4
6.3 While concatenating multiple videos remove audio using
ffmpeg -safe 0 -f concat -i file.txt -vcodec copy -an output.MOV
6.4 Concatenate audio files
ffmpeg -safe 0 -f concat -i file.txt -acodec copy all.mp3
7 Merge video with audio and keeping the shortest duration (from video)
ffmpeg -i output.MOV -i ~/Documents/sounds_youtube/tmp/all.mp3 -map 0:v -map 1:a -filter:a "volume=0.2" -vcodec copy -shortest final.MOV
8 You can also split video.
ffmpeg -i output.MOV -ss 00:09:10 -to 00:10:00 -c copy final.MOV
9 Extract single frame from a video
Somtimes you may want to extract a frame for your thumnail.
ffmpeg -ss 00:02:13 -i input.mp4 -frames:v 1 -y screenshot.png
10 You can also reduce file size drastically using this command.
ffmpeg -i input.mp4 -vcodec libx265 -crf 28 output.mp4
Concatenate videos and reduce file size at the same time.
ffmpeg -safe 0 -f concat -i file.txt -vcodec libx265 -crf 28 output.mp4
Reduce size of a single video and also increase the volume.
ffmpeg -i input.mp4 -map 0:v -map 0:a -filter:a "volume=4" -vcodec libx265 -crf 28 output.mp4
11 Reduce the size of all the videos in a directory.
Prefix small in the filename without changing the extension.
for f in *.MP4;do ffmpeg -i "${f}" -vcodec libx265 -crf 28 "small_${f}";done;
Suffix small in the filename and change the extension.
for f in *.MP4;do ffmpeg -i "${f}" -vcodec libx265 -crf 28 "${f%.*}_small.mp4";done;
Refer to Mastering Shell Scripting to learn more about extracting filename and extension.
12 Recursively go inside directories and execute a command on them
find . -type f -exec echo "'{}' and '{}_small'" \;
13 Find duration of videos in the directory
for f in *.mp4; do ffprobe -v quiet -of csv=p=0 -show_entries format=duration "$f"; done | awk '{sum += $1}; END{print sum/60/60}'
This will print time in hours.
14 Blur
ffmpeg -i 7.2_searching-sharing-and-exporting-issues_sharing-and-exporting.mp4 -filter_complex \ "[0:v]crop=1920:1080:0:0,boxblur=10:enable='between(t,321,323)'[blur1]; \ [0:v]crop=1920:1080:0:0,boxblur=10:enable='between(t,333,336)'[blur2]; \ [0:v][blur1]overlay=0:0:enable='between(t,321,323)'[v0]; [v0][blur2]overlay=0:0:enable='between(t,333,336)'[v]" \ -map "[v]" -map 0:a -c:v libx264 -b:v 3000k -bufsize 6000k -c:a copy blur.mp4
I had to provide bitrate because it was reduced significantly.