Advanced Multimedia Development

1
Advanced Multimedia Development

• MUMT 402
• E-230 (MTCL)
• Tuesday 435pm725pm
• Ichiro Fujinaga
• Ich_at_music.mcgill.ca

2
Introduction

• Overview of this class
• Review
• First object bang

3
Overview of class

• Design, programming, and deployment of music and
  audio in multimedia production. Topics include
• complex MIDI programming
• Low-level audio synthesis algorithms
• interactive music
• timing and scheduling
• Most of programming will be performed within the
  context of Max/MSP environment by developing
  external objects in C.

4
Objectives

• Learn low-level MIDI/audio manipulation concepts
• Learn how to debug
• Learn how to progressively write code
• Learn how to meet deadlines
• Learn how to reverse engineer
• Learn how to read manuals
• Learn how to think

5
Mark distribution

• 15 Mid-term exam 
• 25 Final exam 
• 10 Participation  
• 50 Assignments

6
Assignments

• Weekly assignments
• Assignment policy
• All assignments are due at midnight of the due
  date.
• Late assignments within 48 hours past the
  deadline will be given either D or F.
• Assignments submitted after 48 hours past the
  deadline will be given F.
• Collaboration (www.mcgill.ca/integrity)
• Neatness, elegance, documentation

7
Contact

• Email ich_at_music.mcgill.ca
• Webpage www.music.mcgill.ca/ich
• Phone [phone]x00944
• Office 550 Sherbrooke W.
• Office hours Any time via email or by appointment

8
Music Technology Computer Lab (E230) and linux
accounts

• Get MTCL account from Darryl Cameron
  (darryl_at_music.mcgill.ca)
• Get linux (shell, sftp) account on
  music.mcgill.ca, if you dont have one yet. Ill
  contact Alain Terriault (alaint_at_music.mcgill.ca)
  (with your preferred login name).
• Create your web home page (assignment 1)
• Basic personal info
• Links to your classes
• Place to post your assignments

9
Review I

• What is
• Max
• MSP
• OOP
• Class
• Objects
• Messages
• Encapsulation
• Inheritance (not implemented in Max/MSP)

10
Review II

• What is a
• Compiler
• Library
• Linker
• Shared library
• DLL
• Plugin
• External objects

11
Writing Max External Objects

• Initialization
• main()
• Definition of methods to create new object
• Definition of methods to bind to other messages

12
Preparation

• Documentation
• Max/MSP Externals Tutorial v3.2
• External Objects for Max and MSP 4.5
• Programming environment
• Xcode 2.3

13
The bang object Initialization

• include "ext.h // Required for all Max
  external objectsvoid this_class // Required.
  Global pointing to this class
• Required for all objects
• ext.h in Max/MSP SDK
• contains other header files
• prototypes
• this_class is used as a pointer to this class

14
The bang object Initialization (data)

• typedef struct _bang // Data structure for this
  object t_object b_ob // Must always be the
  first field
• // used by Max void b_out // Pointer
  to an outlet t_bang
• Must start with t_object (see ext_mess.h)
• Max convention first letter followed by
  underscore
• Every object has an inlet
• b_out is a pointer to an outlet

15
The bang object Initialization (methods)

• // Prototypes for methods
• // need a method for each incoming message
• void bang_new(void) // object creation
  method void bang_bang(t_bang bang) // method
  for bang message
• Declaration of class methods that will respond
  to Max messages
• Objects respond to messages from the Max
  environment
• Objects receive messages (integer, float,
  symbol) in their inlets
• Objects methods will process these messages in
  some way and then    send out messages
  using the objects outlets
• This bang object responds to new and bang
  messages

16
The bang object main()

• When an object is created for the first time
• External object is loaded into memory
• main() is executed once and only once
• main() specifies how the object should be
  initialized
• Setup the class
• Allocate memory for the object
• Specify method for the creation of instances of
  the object
• Define messages that the object can respond to
  and bind each message to a method

17
The bang object main() cont.

• void main(void)
• // set up our class create a class definition
• setup(this_class, (method)bang_new, 0L,
  (short)sizeof(t_bang), 0L, 0)
• // bind method "bang_bang to the "bang" message
• addbang((method)bang_bang)
• Setup creates the class
• Get pointer to the class, specify instance
  creation method, instance free method, size of
  each instance, GUI object.
• addbang binds the method to bang message
  coming into the left inlet (addint, addinx,
  addmess, addft, and addftx)  

18
The bang object main() cont.

• int main(void)
• // set up our class create a class definition
• setup(this_class, (method)bang_new, 0L,
  (short)sizeof(t_bang), 0L, 0)
• // bind method "bang_bang to the "bang" message
• addbang((method)bang_bang)
• return (0)
• Setup creates the class
• Get pointer to the class, specify instance
  creation method, instance free method, size of
  each instance, GUI object.
• addbang binds the method to bang message
  coming into the left inlet (addint, addinx,
  addmess, addft, and addftx)  

19
The bang object The object creation function

• void bang_new(void)
• t_bang bang
• // create the new instance and return a pointer
  to it
• bang (t_bang )newobject(this_class)
• bang-gtb_out bangout(bang) // create a bang
  outlet
• return(bang)// must return a pointer to the new
  instance
• Creates an instance of the class by newobject()
• Outlet is created by bangout() and assigned in
  the object s struct

20
The bang object Handling the bang message

• void bang_bang(t_bang bang)
• // send a bang to the outlet bang-gtb_out
• outlet_bang(bang-gtb_out)
• This method is called when bang message is
  received at the left inlet, because of addbang()
• The bang_bang method simply sends a bang
  messages via the outlet via a max method,
  outlet_bang()
• The outlet, bang-gtb_out was created by bangout()

21
Ichs C style

• no space before commas and semicolons
• no space after function names
• space after commas and semicolons
• space before and after an operator
• space after keywords
• vertically align matching braces (optional)
• no magic numbers