How to make a movie constituted of image loops and audio?

Macro MakeMovie(nframes,fRate,wAudio)
    Variable nframes=NumVarOrDefault("gnframes",10)
    Variable fRate=NumVarOrDefault("gwFPS",30)
    Variable wAudio=NumVarOrDefault("gwAudio",2)
    Prompt nframes,"Number of movie frames"
    Prompt fRate,"Frame rate"
    Prompt wAudio,"Sound:",popup "Off;On"
    
    Variable/G gnframes= nframes
    Variable/G gwFPS= fRate
    Variable/G gwAudio= wAudio
    
    DoMakeMovie(nframes,gwFPS,wAudio-1)
end
 
// returns error flag
Function ValidatePath()
    PathInfo moviesPath
    if( V_Flag==0 )
        NewPath/o/Q moviesPath,  SpecialDirPath("Igor Pro User Files", 0, 0, 0 )
        if( V_Flag != 0 )
            return 1        // abort or failure
        endif
    endif
    return 0
End
    
 
Function DoMakeMovie(nframes,fRate,wAudio)
    Variable nframes,fRate,wAudio
    wave scar
    Execute/Q "SetIgorOption VerboseMode=2"
    
    newpath/o IgorSpace, "F:"
    
    ValidatePath()
 
    String fName= "sampleMovie"
    String fExtension= ".mp4"
    
    Variable isMac= CmpStr(IgorInfo(2),"Macintosh") == 0
 
    Make/O/W/N=( 963332/fRate,2) yuanAudio
    SetScale/P x,0,20/ 963332,"s" yuanAudio
   
    variable i=0
    do 
       int a=mod(i,4)
       string nextImage = "pict"+num2str(a+1)+".bmp"
       imageload /O/P=IgorSpace /T=bmp  nextimage
       duplicate/o $nextimage,w
       redimension/n=(259,183,-1) w
       newimage /n=season/s=0 w
   
      if(i==0)  
           if( wAudio)
                fName += "Audio"
                NewMovie/cf=1/O/F=(fRate)/P=moviesPath/S=yuanAudio as fName+fExtension
           else
                NewMovie/cf=1/O/F=(fRate)/P=moviesPath as fName+fExtension
           endif
           if( V_Flag!=0 )
                Print "OpenMovie failed, err= ",V_Flag
                return 0            // probably canceled
           endif
       endif
       
       doupdate
        AddMovieFrame
        killwindow season
        killwaves $nextimage
        if( V_Flag!=0 )
            Print "Add movie frame failed, err= ",V_Flag,", frame ",i
            if( isMac && wAudio )
                Print "Specifing sound may not work on Mac"
            endif
            break 
        endif
        
        i += 1
    while(i<nframes)
    if( wAudio )
            yuanAudio= scar[100000+p]
            AddMovieAudio/Z yuanAudio
            if( V_Flag!=0 )
                Print "Add movie audio failed, err= ",V_Flag 
            endif
    endif
    CloseMovie/Z
    if( V_Flag!=0 )
        Print "Close movie failed, err= ",V_Flag
    endif
    Sleep/S 1       // without this, Mac sometimes gives a file not a movie error; DoUpdate did not help
    PlayMovie/P=moviesPath as fName+fExtension
end