HOW TO: Record macOS screencast as animated GIF

_macOS_screencast_to_animated_GIF.md

Capture screencast

You can capture the screencast video using QuickTime Player.

Capture screen or selection

1. Open Quicktime Player
2. Go to File > New Screen Recording
3. Click the record button and follow the instructions
4. Go to File > Export, choose the highest quality and save as screencast.mov

Capture single window

Download the clickdrag.swift file below.

# Make the clickdrag.swift file executable
chmod +x ~/Downloads/clickdrag.swift

Download the StartWindowRecording.applescript file below and open it with the Script Editor utility.

Change the values of theProcessName and theWindowNumber at the top to the target application window (and window number) that you want to capture.

Choose Script > Run to run the script. This will launch QuickTime Player, start a new screen recording, and select the exact dimensions of the target window.

Finally:

1. Click Start Recording
2. To end the recording, click the stop button in the system menu bar
3. Go to File > Export, choose the highest quality and save as screencast.mov

Convert to GIF

# Install dependencies
brew install ffmpeg 
brew cask install xquartz
open /usr/local/Caskroom/xquartz/2.7.9/XQuartz.pkg
brew install gifsicle

# Convert screencast.mov to screencast.gif
ffmpeg -i screencast.mov -vf scale=800:-1 -r 10 -f image2pipe -vcodec ppm - | convert -delay 5 -layers Optimize -loop 0 - screencast.gif

# View the GIF
open -a Safari screencap.gif

Sources

• https://gist.github.com/dergachev/4627207#instructions
• https://gist.github.com/dergachev/4627207#gistcomment-1311137
• https://gist.github.com/dergachev/4627207#gistcomment-1543177
• http://www.paulcalnan.com/archives/2014/10/quicktime-screen-recording-of-a-single-window.html
• https://gist.github.com/pwc3/e611504878fd3e18ce91#file-start-screen-recording-scpt
• https://gist.github.com/pwc3/ea255791598a79a1bcd9#gistcomment-1985664

clickdrag.swift

#!/usr/bin/env xcrun swift
import Foundation

let kDelayUSec : useconds_t = 500_000

func DragMouse(from p0: CGPoint, to p1: CGPoint) {
    let mouseDown = CGEvent.init(mouseEventSource:nil, mouseType:.leftMouseDown,    mouseCursorPosition:p0, mouseButton:.left)!
    let mouseDrag = CGEvent.init(mouseEventSource:nil, mouseType:.leftMouseDragged, mouseCursorPosition:p1, mouseButton:.left)!
    let mouseUp   = CGEvent.init(mouseEventSource:nil, mouseType:.leftMouseUp,      mouseCursorPosition:p1, mouseButton:.left)!

    mouseDown.post(tap:.cghidEventTap)
    usleep(kDelayUSec)
    mouseDrag.post(tap:.cghidEventTap)
    usleep(kDelayUSec)
    mouseUp.post(tap:.cghidEventTap)
}

func main() {
    let args = UserDefaults.standard

    let x  = CGFloat(args.integer(forKey:"x"))
    let y  = CGFloat(args.integer(forKey:"y"))
    let dx = CGFloat(args.integer(forKey:"dx"))
    let dy = CGFloat(args.integer(forKey:"dy"))

    let p0 = CGPoint(x:x, y:y)
    let p1 = CGPoint(x:x + dx, y:y + dy)

    DragMouse(from: p0, to: p1)
}

main()

StartWindowRecording.applescript

set theProcessName to "Safari"
set theWindowNumber to 1

tell application "System Events"
	tell process theProcessName
		activate
		tell window theWindowNumber
			set thePosition to position
			set theSize to size
		end tell
	end tell
end tell

tell application "QuickTime Player"
	activate
	new screen recording
	delay 1
	tell application "System Events" to key code 49
	delay 1
	do shell script "~/Downloads/clickdrag.swift -x " & (item 1 of thePosition) & " -y " & (item 2 of thePosition) & " -dx " & (item 1 of theSize) & " -dy " & (item 2 of theSize)
end tell

To apply a filter to set saturation to 0 (black and white):

ffmpeg -i screencast.mov -vf "scale=800:-1,hue=s=0" -r 10 -f image2pipe -vcodec ppm - | convert -delay 5 -layers Optimize -loop 0 - screencast.gif

See https://ffmpeg.org/ffmpeg-filters.html#hue