How can I get Binaries File in assets on Flutter?

I'm making a mac os app using flutter

and i need run ffmpeg by process_run package

I put ffmpeg and ffprobe Binaries file on assets , and add it on .yaml file

but how can i get it ?

i did not found these Binaries file on "/Users/me/Library/Containers/milukon.app.flutter/Data" or any where

so , how can i run the cmd like below?

    String _cmd = """
       assets/bash/ffmpeg -v
    """;
    await shell.run(_cmd);

I need know where the Binaries file is