This post is about usage of ffmpeg. How to start using it from a basic level and can we use it in production environment?

Basic level Usage

Steps:

  1. We can download ffmpeg from here link
  2. Easiest way is to install static build, Based on our environments, we can choose win,mac or linux based static builds
  3. Just download static build and unzip it. We are ready to use ffmpeg now.
  4. We can add extracted folder path to PATH variable, so that every time we don’t need to go to folder for running ffmpeg.

Various FFMPEG commands:

  1. Clipping the Video
1
2
3

 
   ffmpeg -ss starttime -i source_video.mp4 -to duration -q:a 0 -q:v 0 output_video.mp4

This above command will clip the video from starttime specified to duration of video. You can get output video in any format you like, just enter specific format of output video.

  -q:a 0

This is for specified for 0 quality loss for audio. Resulting file size will be bigger.

  -q:v 0

This is specified for 0 quality loss for video.

  1. Apply Fade in Fade out
1
2

 ffmpeg -i source_video.mp4 -sseof -1 -copyts -i source_video.mp4 -filter_complex "[1]fade=out:0:30[t];[0][t]overlay,fade=in:0:30[v]; anullsrc,atrim=0:1[at]acrossfade=d=1,afade=d=1[a]" -map "[v]" -map "[a]" -q:v 0 -q:a 0 output_video.mp4

This will apply fade in and fade out for starting 30 frames and ending 30 frames of a video. You can play around with frame nos.

  1. Convert Mp4 to ts format

We shouldn’t merge two mp4 files as such. We should convert them to ts format first and then merge them. Otherwise we will see lot of issues like audio sync issue etc.

1
2
3

 
 ffmpeg -i source_video.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts intermediate.ts
  1. Merge Ts files and convert to mp4 format
1
2
3

 
 ffmpeg -f concat -safe 0 -i file.txt -q:a 0 -q:v 0 -bsf:a aac_adtstoasc output_video.mp4

where file.txt has following content

1
2
3
4
5

 
 file '/path/to/file/1.ts' 
 file '/path/to/file/2.ts' 
 file '/path/to/file/3.ts'

Taken from here

Sometimes there are audio sync issues when we merge video files of different audio rate. This can be seen quite significantly if we open the merged video in a browser rather than a video player like vlc which automatically resolves audio sync issues.

To properly merge video clips, we have to make sure all video files have same audio rate. For that first we can see what is the audio rate and set that audio rate.

  1. Get Audio Rate
1
2

 ffprobe -v error -select_streams a:0 -show_entries stream=sample_rate -of default=noprint_wrappers=1:nokey=1 source_video.mp4
  1. Set Audio rate
1
2
3

 
 ffmpeg -i source_video.mp4 -ar sample_rate output_video.mp4

Sometime we wish to get thumbnail of a video. We can do that by

1
2

 ffmpeg -i source_video.mp4 -vf thumbnail,scale=640:360 -frames:v 1 thumbnail.png

For each of the above commands we can add -y parameter before output_video.mp4 to overwrite file if already exists.

Building FFMPEG

FFMPEG has GPL licence legal

For using under LGPL licence We can compile FFmpeg without “–enable-gpl” and without “–enable-nonfree”.

For compilation guide follow this guide.

Check licences using

ffmpeg -L

Include libraries based on your requirements.

Happy Coding.