While operating ffmpeg, it is easy to apply the fade in and fade out feature to video using the 'fade' filter. For audio, the a fade filter can be used to achieve a similar effect.ffmpeg -i video.mp4 -vf \\"fade=t=in:st=0:d=3\\" -c:a copy out.mp4A black screen will appear and fade in to full view over 3 seconds.ffmpeg -i video.mp4 -vf \\"fade=t=out:st=10:d=5\\" -c:a copy out.mp4The video starts fading to black over 5 seconds towards the 10 second mark.ffmpeg -i music.mp3 -af \\"afade=t=in:st=0:d=5\\" out.mp3The audio file starts at a low volume and fades into full over 5 seconds.ffmpeg -i music.mp3 -af \\"afade=t=out:st=5:d=5\\" out.mp3The audio file starts fading to zero volume over 5 seconds starting at the 5 second mark.ffmpeg -i video.mp4 -vf \\"fade=t=in:st=0:d=10,fade=t=out:st=10:d=5\\" -c:a copy out.mp4Applying both fade in and out effects at the same time is possible to avoid re-encoding twice.