Onder's FFmpeg Cheat Sheet

Here i note scripts and commands i mostly use while working on videos. If you somehow end up here, feel free to take a look :)

Scaling Videos

ffmpeg -i input.avi -vf scale=320:240 output.avi

Scaling Images

ffmpeg -i input.mp4 -vf scale=320:-1 output.mp4

To scale a video or a photo while retaining its aspect ratio, you need to set either one of the height or width parameter and set the other parameter to -1. The resulting video will have a resolution of 320x180. This is because 1920 / 320 = 6. Thus, the height is scaled to 1080 / 6 = 180 pixels.

Scaling a Folder of Images

for f in *.PNG; do ffmpeg -i "$f" -vf scale=640:-1 "images_640/${f%%.png}.png"; done

Write and save the following code in a bash file (eg: "scale.sh").

Splitting a Video to Frames

mkdir frames
ffmpeg -i input.mp4 frames/frame_%03d.jpg

Splitting Videos in a Folder to Frames Using Python

import subprocess

video=0
while video < 45: # I had 45 videos named like VID000.mp4 , VID001.mp4 ...
	name = 'VID' + str(video).zfill(2)
	name2 = name + '.mp4'
	subprocess.run(f'mkdir {name}', shell = True)
	result = subprocess.run(f'ffmpeg -i {name2} {name}/{name}_%03d.jpg', shell = True)
	print(result)
	video += 1

With subprocess we can execute shell commands in a python script. Write this code and save it in a python file (eg: "split.py"). You may need sudo privilages to run it.

sudo python split.py

If you are more comfortable with bash scripts you can do it like what i did on compressing multiple videos in a folder down below.

Merging Frames to a Video with FFmpeg

FPS = 30
OUTPUT_NAME = "OUTPUT.mp4"

ffmpeg -r $FPS -f image2 -s 1920x1080 -i frame_%03d.png -vcodec libx264 -crf 25  -pix_fmt yuv420p $OUTPUT

"frame_%03d.png" means all frames from "frame_001.png" to "frame_999.png". In order to get all frames with ".png" extension use "*png"

Compressing Videos

INPUT_NAME = "INPUT.mp4"
OUTPUT_NAME = "OUTPUT.mp4"

ffmpeg -i $INPUT_NAME -vcodec libx265 -crf 28 $OUTPUT_NAME

Compressing a Folder of Videos

Write and save the following code in a bash file (eg: "compress.sh"), don't forget to change path variables

#!/bin/bash
for filename in /PATH_TO_INPUT_VIDEOS/*.mp4; do
   ffmpeg -i "$filename" -vcodec libx265 -crf 28 /PATH_TO_OUTPUT_VIDEOS/"$(basename "$filename" .mp4).mp4"
done
~

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