AppleScript + QuickTime — batch trim + create edit + export video - applescript

Question

I'm looking for some help.
What I'm trying to do is to have AppleScript open a folder of videos, then get QuickTime to randomly trim them (as in the start frame from where it trims) and then have a variable length of the trim itself (say random between 1sec to 2sec as boundaries for the new 'clip'). After trimming and creating the new 'edit' (it would add this new random trimming to all the videos in the folder then add to timeline). QT then needs to export the edit to a new folder.
In summary, trying to make a quick auto-editing app that can just pick random selects from a folder full of videos then save an edit to a new video.
ANY help with this would be hugely appreciated!
I've been trying but to nail avail (I'm fairly new to coding to going around in circles).
Thanks!
Dylan

Answer 1

Like #CJK, I would recommend you use bash and ffmpeg as they are both available on macOS and both better known and more widely applicable than Applescript and QuickTime.
IMHO, as Apple does not ship a package manager, you would be well advised to use homebrew to install, update and remove packages. It is available on the homebrew website.
Once you have that, you can find any package you want with:
brew search packageXYZ
So, you can now install ffmpeg with:
brew install ffmpeg
Now you would want a bash script that:
loops through all your ".mov" files in a directory
gets their lengths
calculates a random duration
calculates a random start time
extracts that piece of video as a clip
and, finally at the end, assembles all the clips together
That will look something like this, which I would suggest you save in a bash script called $HOME/RandomClips
#!/bin/bash
# Set up globbing
shopt -s nullglob nocaseglob
# Clear list of files we are going to concatenate
> list.txt
N=1
# Loop through all ".MOV" files
for f in *.MOV ; do
# Tell user which one we are processing
echo Processing file $f
# Get length of this video in seconds
duration=$(mdls -raw -name kMDItemDurationSeconds "$f")
echo ... Duration: $duration
# Generate a random clip length less than 5 seconds
((seconds=RANDOM%5))
echo ... Clip length: $seconds
# Generate start time
((start=RANDOM%(duration-seconds)))
echo ... Start time: $start
# Extract clip into file called "Clip-1.mov", "Clip-2.mov" etc
clipname="Clip-$N.mov"
echo ... Extracting $clipname
ffmpeg -hide_banner -ss $start -i "$f" -t $seconds -pix_fmt yuv420p "$clipname"
# Add name of this clip to the list of files to concatenate at the end
echo "file $clipname" >> list.txt
# Increment clip counter
((N=N+1))
done
# Now join together all the extracted clips into a single file
ffmpeg -hide_banner -f concat -i list.txt -c copy -pix_fmt yuv420p mergedVideo.mov
Now you need to make that executable, just necessary once, with:
chmod +x $HOME/RandomClips
Then use cd to navigate to a directory of movies:
cd some/place/with/movies
and run the script with:
$HOME/RandomClips
The script is not the most robust or well-tested in the entire world but it should be 90+% good. You may have to resize videos to a fixed size so they all match formats. Likewise with codecs. Probably ask another question if that becomes an issue.
No-one said answers have to be 100% perfect, and as no-one else has suggested anything, this will hopefully get you well on your way.
If you want to debug the script, you can:
read the debug output line by line
check all the extracted clips look correct, i.e, "Clip-1.mov", "Clip-2.mov"
read the file called "list.txt" to see if it contains all the clips