Call pdf2fax(IO.Path.Combine(Application.StartupPath, "input.pdf"), _
     IO.Path.Combine(Application.StartupPath, "output.tif"), "tiffg32d", "204x196")


  Public Sub pdf2fax(ByVal s_InputFile As String, ByVal s_OutputFile As String, _
   ByVal s_DEVICE As String, ByVal s_Resolution As String)
    Dim astrArgs(13) As String
    astrArgs(0) = "pdf2fax" 'The First Parameter is Ignored
    astrArgs(1) = "-q"
    astrArgs(2) = "-sDEVICE=" & s_DEVICE '"-sDEVICE=tiffg32d"
    astrArgs(3) = "-r" & s_Resolution '"-r204x98"
    astrArgs(4) = "-dAdjustWidth=1" 'иначе не делает 1728 для lzw/packbits
    astrArgs(5) = "-dBATCH"
    astrArgs(6) = "-dPDFFitPage"
    astrArgs(7) = "-dNOPAUSE"
    astrArgs(8) = "-dFillOrder=2"
    astrArgs(9) = "-sOutputFile=" & s_OutputFile
    astrArgs(10) = "-f"
    astrArgs(11) = s_InputFile
    astrArgs(12) = "-c"
    astrArgs(13) = "quit"
    Try : CallGS(astrArgs) : Catch : End Try
  End Sub

  Private Declare Function gsapi_set_stdio Lib "gsdll32.dll" _
   (ByVal lngGSInstance As IntPtr, _
   ByVal gsdll_stdin As StdIOCallBack, _
   ByVal gsdll_stdout As StdIOCallBack, _
   ByVal gsdll_stderr As StdIOCallBack) As Integer

  '--- Delegate function for callbacks
  Private Delegate Function StdIOCallBack(ByVal handle As IntPtr, _
    ByVal Strz As IntPtr, ByVal Bytes As Integer) As Integer

  '--- Dummy callback for standard input, standard output, and errors
  Private Function InOutErrCallBack(ByVal handle As IntPtr, _
   ByVal Strz As IntPtr, ByVal Bytes As Integer) As Integer
    Debug.Print("Callback")
    Return 0
  End Function
 
...
    Dim StdErrCallback As StdIOCallBack
    Dim StdInCallback As StdIOCallBack
    Dim StdOutCallback As StdIOCallBack

    StdInCallback = AddressOf InOutErrCallBack
    StdOutCallback = AddressOf InOutErrCallBack
    StdErrCallback = AddressOf InOutErrCallBack

   ' Capture stdio
    intReturn = gsapi_set_stdio(intGSInstanceHandle, _
     StdInCallback, StdOutCallback, StdErrCallback)

    intReturn = gsapi_set_stdio(intGSInstanceHandle, _
     Nothing, Nothing, Nothing)

  Private Declare Function gsapi_init_with_args Lib "gsdll32.dll" _
   (ByVal lngGSInstance As IntPtr, ByVal lngArgumentCount As Integer, _
   <MarshalAs(UnmanagedType.LPArray, ArraySubType:=UnmanagedType.LPStr)> _
   ByVal argv() As String) As Integer

    Call pdf2fax(IO.Path.Combine(Application.StartupPath, "Привет.pdf"), _
     IO.Path.Combine(Application.StartupPath, "hello.tif"), "tiffg32d", "204x196")

Error: /undefinedfilename in (C:\\Setup\\ghostscript\\TestGSAPI\\TestGSAPI\\bin\\Debug\\\317\360\350\342\345\362.pdf)

  Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
    Call pdf2fax(IO.Path.Combine(Application.StartupPath, "Davorka Žimbrek - Sd.pdf"), _
     IO.Path.Combine(Application.StartupPath, "davorka.tif"), "tiffg32d", "204x196")
  End Sub

Error: /undefinedfilename in (C:\\Setup\\ghostscript\\TestGSAPI\\TestGSAPI\\bin\\Debug\\Davorka Zimbrek - Sd.pdf)

Declare Unicode Function gsapi_init_with_args...

GSDLLEXPORT int GSDLLAPI gsapi_init_with_args(void *instance,
    int argc, char **argv);

#ifdef __WIN32__
GSDLLEXPORT int GSDLLAPI gsapi_init_with_argsA(void *instance,
    int argc, char **argv);

GSDLLEXPORT int GSDLLAPI gsapi_init_with_argsW(void *instance,
    int argc, wchar_t **argv);
#endif

  Private Const GS_ARG_ENCODING_UTF16LE As Integer = 2

  Private Declare Function gsapi_set_arg_encoding Lib "gsdll32.dll" _
   (ByVal lngGSInstance As IntPtr, _
   ByVal encoding As Integer) As Integer
  Private Declare Unicode Function gsapi_init_with_args Lib "gsdll32.dll" _
   (ByVal lngGSInstance As IntPtr, ByVal lngArgumentCount As Integer, _
   <MarshalAs(UnmanagedType.LPArray, ArraySubType:=UnmanagedType.LPWStr)> _
   ByVal argv() As String) As Integer

   intReturn = gsapi_set_arg_encoding(intGSInstanceHandle, GS_ARG_ENCODING_UTF16LE)
      intReturn = gsapi_init_with_args(intGSInstanceHandle, NumArgs, Args)

  Private Declare Function gsapi_set_arg_encoding Lib "gsdll32.dll" _
   (ByVal lngGSInstance As IntPtr, _
   ByVal encoding As Integer) As Integer
  Private Declare Function gsapi_init_with_args Lib "gsdll32.dll" _
   (ByVal lngGSInstance As IntPtr, ByVal lngArgumentCount As Integer, _
   ByVal argv() As IntPtr) As Integer

  Private Const GS_ARG_ENCODING_UTF8 As Integer = 1

  Public Sub CallGS(ByVal ParamArray Args() As String)
    If IsNothing(Args) Then Exit Sub

    Dim intReturn As Integer
    Dim intGSInstanceHandle As IntPtr
    'Dim NumArgs As Integer
    Dim callerHandle As IntPtr

    ' Load Ghostscript and get the instance handle
    intReturn = gsapi_new_instance(intGSInstanceHandle, callerHandle)
    If intReturn < 0 Then Exit Sub

    intReturn = gsapi_set_arg_encoding(intGSInstanceHandle, GS_ARG_ENCODING_UTF8)

    Dim utf8argv As IntPtr()
    ReDim utf8argv(0 To UBound(Args))
    For i As Integer = 0 To UBound(utf8argv)
      Dim buffer As Byte()
      ReDim buffer(0 To System.Text.Encoding.UTF8.GetByteCount(Args(i))) ' null-terminator allocated
      System.Text.Encoding.UTF8.GetBytes(Args(i), 0, Strings.Len(Args(i)), buffer, 0)
      utf8argv(i) = Marshal.AllocHGlobal(UBound(buffer) + 1)
      Marshal.Copy(buffer, 0, utf8argv(i), UBound(buffer) + 1)
    Next

    '--- Run Ghostscript using specified arguments
    intReturn = gsapi_init_with_args(intGSInstanceHandle, UBound(Args), utf8argv)

    For i As Integer = 0 To UBound(utf8argv)
      Marshal.FreeHGlobal(utf8argv(i))
    Next

    ' Stop the Ghostscript interpreter
    intReturn = gsapi_exit(intGSInstanceHandle)

    ' release the Ghostscript instance handle
    gsapi_delete_instance(intGSInstanceHandle)
  End Sub

  Private Const GS_ARG_ENCODING_UTF16LE As Integer = 2

  Public Sub CallGS(ByVal ParamArray Args() As String)
    If IsNothing(Args) Then Exit Sub

    Dim intReturn As Integer
    Dim intGSInstanceHandle As IntPtr
    'Dim NumArgs As Integer
    Dim callerHandle As IntPtr

    ' Load Ghostscript and get the instance handle
    intReturn = gsapi_new_instance(intGSInstanceHandle, callerHandle)
    If intReturn < 0 Then Exit Sub

    intReturn = gsapi_set_arg_encoding(intGSInstanceHandle, GS_ARG_ENCODING_UTF16LE)

    Dim utf16argv As IntPtr()
    ReDim utf16argv(0 To UBound(Args))
    For i As Integer = 0 To UBound(utf16argv)
      Dim buffer As Byte()
      ReDim buffer(0 To System.Text.Encoding.Unicode.GetByteCount(Args(i))) ' null-terminator allocated
      System.Text.Encoding.Unicode.GetBytes(Args(i), 0, Strings.Len(Args(i)), buffer, 0)
      utf16argv(i) = Marshal.AllocHGlobal(UBound(buffer) + 1)
      Marshal.Copy(buffer, 0, utf16argv(i), UBound(buffer) + 1)
    Next

    '--- Run Ghostscript using specified arguments
    intReturn = gsapi_init_with_args(intGSInstanceHandle, UBound(Args), utf16argv)

    For i As Integer = 0 To UBound(utf16argv)
      Marshal.FreeHGlobal(utf16argv(i))
    Next

    ' Stop the Ghostscript interpreter
    intReturn = gsapi_exit(intGSInstanceHandle)

    ' release the Ghostscript instance handle
    gsapi_delete_instance(intGSInstanceHandle)
  End Sub

  '--- Delegate function for callbacks
  Private Delegate Function StdIOCallBack(ByVal handle As IntPtr, _
    ByVal Strz As IntPtr, ByVal Bytes As Integer) As Integer

  '--- Dummy callback for standard input, standard output, and errors
  Private Function InOutErrCallBack(ByVal handle As IntPtr, _
   ByVal Strz As IntPtr, ByVal Bytes As Integer) As Integer
    Debug.Print("Callback")
    Return 0
  End Function

/* Set the callback functions for stdio
 * The stdin callback function should return the number of
 * characters read, 0 for EOF, or -1 for error.
 * The stdout and stderr callback functions should return
 * the number of characters written.
 * If a callback address is NULL, the real stdio will be used.
 */
GSDLLEXPORT int GSDLLAPI
gsapi_set_stdio(void *instance,
    int (GSDLLCALLPTR stdin_fn)(void *caller_handle, char *buf, int len),
    int (GSDLLCALLPTR stdout_fn)(void *caller_handle, const char *str, int len),
    int (GSDLLCALLPTR stderr_fn)(void *caller_handle, const char *str, int len));

  Private Function InOutErrCallBack(ByVal handle As IntPtr, _
   ByVal Strz As IntPtr, ByVal Bytes As Integer) As Integer
    Debug.Print(Marshal.PtrToStringAnsi(Strz, Bytes))
    Return Bytes
  End Function

Public Function gsdll_stdin _
 (ByVal intGSInstanceHandle As Long, ByVal StrZ As Long, ByVal intBytes As Long) As Long
  ' We don't have a console, so just return EOF
  gsdll_stdin = 0
End Function

Public Function gsdll_stderr(ByVal intGSInstanceHandle As Long, ByVal StrZ As Long, ByVal intBytes As Long) As Long
  gsdll_stderr = gsdll_stdout(intGSInstanceHandle, StrZ, intBytes)
End Function

Public Function gsdll_stdin _
 (ByVal intGSInstanceHandle As Long, ByVal StrZ As Long, ByVal intBytes As Long) As Long
  ' We don't have a console, so just return EOF
  gsdll_stdin = 0
End Function

Public Function gsdll_stderr(ByVal intGSInstanceHandle As Long, ByVal StrZ As Long, ByVal intBytes As Long) As Long
  gsdll_stderr = gsdll_stdout(intGSInstanceHandle, StrZ, intBytes)
End Function

Public Function gsdll_stdin _
 (ByVal intGSInstanceHandle As Long, ByVal StrZ As Long, ByVal intBytes As Long) As Long
  ' We don't have a console, so just return EOF
  gsdll_stdin = 0
End Function

Public Function gsdll_stdout _
 (ByVal intGSInstanceHandle As Long, ByVal StrZ As Long, ByVal intBytes As Long) As Long
  ' If you can think of a more efficient method, please tell me!
  ' We need to convert from a byte buffer to a string
  ' First we create a byte array of the appropriate size
  Dim aByte() As Byte
  ReDim aByte(intBytes)
  ' Then we get the address of the byte array
  Dim ptrByte As Long
  ptrByte = VarPtr(aByte(0))
  ' Then we copy the buffer to the byte array
  CopyMemory ptrByte, StrZ, intBytes
  ' Then we copy the byte array to a string, character by character
  Dim str As String
  Dim i As Long
  For i = 0 To intBytes - 1
    str = str + Chr(aByte(i))
  Next
  ' Finally we output the message
  Debug.Print (str)
  'MsgBox (str)
  gsdll_stdout = intBytes
End Function

Public Function gsdll_stderr(ByVal intGSInstanceHandle As Long, ByVal StrZ As Long, ByVal intBytes As Long) As Long
  gsdll_stderr = gsdll_stdout(intGSInstanceHandle, StrZ, intBytes)
End Function