How to add language to subtitle file name?

[Dr-W00]

I'm using faster-whisper.exe in a Windows command line to batch process multiple files. It's working great, but I would like to get the file names as xxxx.en.srt, rather than xxxx.srt. I tried --help and saw --postfix. It seemed to be what I was looking for. The original command that works fine was:

whisper-faster.exe "m:\transcode\results*.mkv" --language en --model medium --output_dir source

The revised command to get the .en. in is:

whisper-faster.exe "m:\transcode\results*.mkv" --language en --model medium --output_dir source --postfix true

The error I get is:

whisper-faster.exe: error: unrecognized arguments: true

I've tried true, True, and 1. Same error. What am I doing wrong?

[Dr-W00]

Ooops. Nevermind. There is no argument for --postfix. It's either included in the command (and adds _en to the file name) or left off and keeps the same name as the source file.