ffmpeg-notes.md

FFmpeg

A list of useful ffmpeg commands

See the video meta data

ffprobe video.mp4

Covert to High Efficiency Video Coding (HEVC) format

ffmpeg -c:v libx265 -c:a copy -i input.mp4 out.mp4

IMO, HEVC is so far (2020-04-15) the best codec for video. Very good compression rate and encoding performance.

WebM has a lot of limitations. I have not find a performant way to encode to WebM with FFmpeg.

Resize (scale) the video to 720p

ffmpeg -vf scale=-1:720 -c:a copy -i input.mp4 out.mp4

-1 means it will automatically calculate the output width with the source ratio.

Skip to certain time

ffmpeg -ss 00:00:15 -i input.mp4 -codec copy out.mp4

The order of -ss actually matters (surprise!). It seems one uses the closest frame before the encoding, another uses the frame after the encoding.

Specify duration

ffmpeg -i input.mp4 -codec copy -t 15 out.mp4

Audio parameters

• -c:a copy: copy the audio stream
• -an: ignore the audio stream

Script to concat GoPro video files

function concat-gopro-video -d 'Concat all GoPro video files in the folder'
  set files (ls GX*.MP4)
  rm files.txt
  for file in $files
    echo "file '$file'" >> files.txt
  end
  cat files.txt
  sleep 1
  ffmpeg -f concat -safe 0 -i files.txt -c copy $argv[1]
  log info "Complete concat video '$argv[1]'"
end

Example of the text file for merging video

file 'video1.mp4'
file 'video2.mp4'