set muxer to POSIX path of (path to resource "mxf-muxer" in directory "Scripts")
set foldercount to 0
 
tell application "Finder"
    set FolderPath to (choose folder with prompt "Pick the folders containing the files to process:" with multiple selections allowed)
    
    set foldercount to count FolderPath
    
    if (foldercount = 1) then
        set inPath to POSIX path of FolderPath as text
        set Foldername to name of folder FolderPath as text
        
        set infile to "no"
        tell application "Finder" to if exists inPath & Foldername & ".MP4" as POSIX file then set infile to "yes"
        
        if (infile = "no") then
            display dialog ("There is no file: \"" & inPath & Foldername & ".MP4" as text) & "\". Please select (multiple) folders which contains MP4 files!" buttons {"Cancel", "Select Folders"} default button "Select Folders"
            
            if button returned of result = "Select Folders" then
                set FolderPath to (choose folder with prompt "Pick the folders containing the files to process:" with multiple selections allowed)
            else
                return
            end if
        else
            display dialog "You have only select one folder, are you sure that you only want to process one file?" buttons {"Select Folders", "Continue"} default button "Continue"
            
            if button returned of result = "Select Folders" then
                set FolderPath to (choose folder with prompt "Pick the folders containing the files to process:" with multiple selections allowed)
            end if
        end if
    end if
    
    set filesString to ""
    repeat with file_ in FolderPath
        set filesString to filesString & " " & quoted form of (POSIX path of file_)
    end repeat
    
    tell application "Terminal"
        activate
        do script quoted form of muxer & filesString
    end tell
end tell