Why doesn't ${1:r} strip file extension in my zsh script?

Question

I'm writing a zsh script that automates some video encoding. The file to be converted will be the first parameter to the script, which contains this line:

ffmpeg -i $1 -ac 0 -vcodec libx264 -b:v 500k -crf 20 ${1:r}.mp4

I expected ${1:r}.mp4 to create a file with the same name as my .mov input, but with the .mp4 file extension replacing .mov. But instead I get input.mov.mp4. Why isn't the :r modifier stripping the file extension?

Answer 1

I experienced something similar and it seems like zsh doesn't accept :r on the positional arguments. Instead you could do something like this:

file=${1}
ffmpeg -i $1 -ac 0 -vcodec libx264 -b:v 500k -crf 20 ${file:r}.mp4