AUTHOR: Dave Headlam
TITLE: Multimedia for Music Study on the Web: Macromedia Director
KEYWORDS: multimedia, Director, Web
Dave Headlam*
Eastman School of Music
26 Gibbs Street
Rochester, New York 14604
dhlm@theory.esm.rochester.edu
ABSTRACT:
The advent of powerful, widely accessible, and financially viable personal
computers with network connections on the World Wide Web has lead to exciting
possibilities for creating musically meaningful presentations for teaching,
performing, and researching music and disseminating them easily to colleagues,
classes, or even to a potentially vast mass audience. These presentations
can combine sound, images, animation, and interaction for stimulating and
interesting results. The downsides of learning different programming languages,
understanding Web page design and networking, dealing with multiple platforms
(principally MacIntosh and Windows), and the problems of generating sound
on different computers have a solution in the multimedia authoring program
Director and its Web counterpart Shockwave, from Macromedia. This paper
outlines the format of Director in its Web version with an emphasis on its
potential for sound, and includes some demonstration files, and closes with
some considerations of technique and content in web authoring for educational
purposes.
1. Introduction
2. Educational and Research Writings on Music Using Computers
3. Files on the Web: Quality, Quantity, and Convenience
4. Sound on the Computer from the Web
5. Web Authoring: Browsers and HTML
6. Shockwave plug-in
7. Director
8. Music Analysis on the Web with Minimal Scripting: An Example
9. Scripting
10. Teaching Music Theory: A Scripted Example
11. Streaming Audio
12. More on Shockwave: Web Programming
13. Conclusion
----------------
1. Introduction
[1.1] With the advent of powerful, widely accessible, and financially viable personal computers with network connections on the World Wide Web, musicians of widely varying interests are presented with an intriguing prospect: the possibility of creating musically meaningful presentations for teaching, performing, and researching music and disseminating them easily to colleagues, classes, or even to a potentially vast mass audience. These presentations can combine sound, images, animation, and interaction for stimulating and interesting results. The frustrating downside to this picture is, of course, the necessity of learning different programming languages, understanding Web page design and networking, dealing with multiple platforms (principally MacIntosh and Windows), and, worst of all, solving the problems of generating sound on different computers.
[1.2] Fortunately, a solution to these obstacles exists in the multimedia authoring program Director and its Web counterpart Shockwave, from Macromedia. This program, currently at version 6.0, is available in an educational form for around $300 and is well worth the time and effort to learn. In this paper, I will outline the format of Director in its Web version with an emphasis on its potential for sound, and include some demonstration files. I have used Director only on the Macintosh, and this article is written from that perspective, but the program exists in almost the same form in Windows versions, with differences noted clearly in the documentation. The Web compiler, Shockwave, allows authors to compile Director files for use on the Web, and a Shockwave plug-in for Web browsers allows users to access the Director program in a suitable format. I have used Shockwave only with the browser Netscape Navigator, but other browsers also support Shockwave. (Throughout this article, highlighted words like the previous "author," plug-in," "Web browsers," and "user," are linked to explanations--if you are viewing with frames, text explanations, similarly to footnotes, will appear in the frame below. Some links are to images or movies; these will appear in a new window which will be on top of this window. You can move the new upper window over to the right of your screen so that you can look at the image and see the associated text. This will be a more cumbersome when the larger movies appear in the upper window. When you are down with the image or movie in the upper window, just click it in the upper left hand corner to get rid of it. If you are playing a movie with sound, let the sound finish before closing the window; in the case of a longer sound below, I have included a "pause" button to stop the sound. This will hopefully prevent your browser from crashing--an event which has happened to me on occasions when I was starting and stopping movies with sound.)
2. Educational and Research Writings on Music Using Computers
[2.1] The computer digital "revolution" is often compared to the development of the printing press in the 1500s. The printing press allowed for wide dissemination of reading material as well as musical scores. While books were illustrated, combining the visual with the printed word, for musicians books and scores separated the visual from the aural. An educational industry has grown up around attempts to recombine these two aspects, usually with value placed on the ability to conjure sound from image using internal musical production and by developing musical memory. The computer, however, allows authors to combine sound, text, and images, thus creating a true "musical book."
[2.2] Those who believe in the split between the visual and aural might be skeptical of the computer's sound production capabilities, regarding them as a crutch similar to using a piano for sight-singing or part-writing. Those who regard it as a benefit when the visual and aural are joined in a musical environment will find truly new uses for computers in musical production, education, and research The trick, I believe, is to use the computer in ways that it is uniquely suited for, and not to "translate" books or musical scores into computer programs with the same goals and perceived limitations. Several interesting uses of computers, in Computer Aided Instruction (CAI) and with Hypercard Stacks have and are emerging, as well as some innovative Web page designs, and it is my hope that musicians will be stimulated by this discussion of Director to keep developing new tools and paradigms in this area.
3. Files on the Web: Quality, Quantity, and Convenience
[3.1] The first consideration for Web authoring is the tradeoff between the quality of the images or sound viewed and the quantity and size of files required. These are in direct proportion: the larger the file, the greater the amount of information, and the better the resulting quality. However, on the Web, quantity is also inversely proportional to download time and ease of use. Thus, the larger the file, the longer is the time it takes for the client computer to receive the information from the server, and the more taxing the requirements of the downloaded file on the client computer in terms of memory and processing time.
[3.2] At least five solutions have arisen in response to this situation: 1) use of small files with often ingenious solutions to the limitations and/or acceptance of a lower quality; 2) development of compression programs that allow files to be sent in a smaller, compressed form from the server and then be expanded on the client computer; 3) breaking down of files into smaller components that are downloaded on demand; 4) linking to external media such as images, sound, and video (instead of copying them into a program so they are internal or inline), which are downloaded separately and on demand; and 5) streaming of files that only need to be partially downloaded before functioning, particularly with sound and video files, which tend to be large. Director's Web design incorporates all of these solutions but allows for less reliance on the first solution than has been the case on the Web.
4. Sound on the Computer from the Web
[4.1] As those with experience creating or receiving sound on personal computers from the Web can attest, it is often an apparently chancy and unpredictable procedure. Why is this the case? Transmitting images and texts on Web pages works almost 100% of the time, but sound requires a few conditions be set. Director's Shockwave plug-in handles the sound playback requirements for the most part, but it is useful to know a bit about sound files on the Web to use sound efficiently.
[4.2] Sound files have several forms. First, as relatively large files, they contain numbers that are representations of actual sound signals, carrying information about amplitude and time dimensions created from an Analog to Digital converter. Sound files are in two sections, a "header" containing information relating to the control and format of the data, and the data itself. The header features control settings such as whether the sound is mono or stereo, what the maximum amplitude is, what the sample rate is, what the bit rate is, etc.. The remainder of the file, the raw sound data, is interpreted according to the settings in the header. To hear the sound, the numbers must be fed into a Digital-to-Analog converter to convert numbers to electrical signals that can be processed into sound, similarly to a home stereo setup with a CD player. This setup is included in most computers sold within the last few years, which all have CD-ROMS, but the client computer and its browser must also have some sort of program or plug-in to interpret the sound file properly and link up with the computer's sound hardware. Using Netscape, useful plug-ins related to sound are Quicktime from Apple, and LiveAudio; these programs can handle the usual .AIF (MacIntosh) and .WAV (Window) sound file formats, as well as others. Director has its own sound format, .SWA, which is incorporated into its Shockwave plug-in.
[4.3] When discussing digital sound quality, reference is made to bits, bytes, and samples: the more bits, bytes, and samples in the representation, the better the sound quality and the larger the file. The standard Web sound quality, 8-bit and 22050 (or less) sample rate, is intolerable for musicians, but it is used because a mono sound file of 8-bit, 22050 samples (uncompressed) takes about 22 Kilobytes (KB) per second or 1.3 Megabytes (MB) per minute, while a CD-quality stereo 16-bit, 44100 sample file takes 166.4 KB per second or about 10 MB per minute in size. A mono 16/44100 file, perfectly acceptable, is 88.2 KB/s or about 5 MB/m, but a good compromise file size is mono 16/22050, which requires 44 KB/s or 2.5 MB/m. Even though sound files are compressed, with ratios of 3:1 or 4:1 common, they are still relatively large. With download times of, on average: 1 KB/second for a 14.4 Kilobit (Kb) modem, 3 KB/second for 28.8 Kb modem, 5 KB/second for a 64 Kbs connection, and about 30 KB/second for higher speed connections, such as the "T1" connection often found in universities, sizes of sound files are a constant consideration.
[4.4] To get sound files to a more manageable size, several compression procedures are used, which cut down on the amount of numbers used to represent the signal. Audio compression is a complex topic beyond the bounds of this article, but Director and Sound Edit 16 have a particularly good compression feature in Shockwave Audio (discussed below), which allows for an acceptable quality of 16 bit/22050 sample, and provides for at least a 6:1 compression ratio (compressed file is 1/6 the size of the original).
[4.5] Other common types of sound files are Midi (Musical Instrument Digital Interface) files, that contain no information about the actual sound and so are quite compact, and files like Mod files that contain mostly Midi-type information but also a few sound samples. Midi files have the advantage of being small, as they contain only information about frequency, duration, attack, articulation, etc. The disadvantage is that the resulting sound is entirely the result of the client computer system, which can be good or bad, depending on the prescence of synthesized sound sources. One useful development is the inclusion of a software synthesizer in Apple's Quicktime 2.5, so that Midi files can play directly through the MacIntosh's Sound Manager. Director can use the same Midi tools as Apple's Hypercard, as part of its overall compatibility with Hypercard Xcommands. Mod files and others with a few sounds and lots of control instructions have been staples of computer games for years; they allow the author to control the resulting sound and have small file sizes. There is no record of Director uses of Mod files, at least that I have found, but they might be useful when specific sounds are desired for extensive sounds.
5. Web authoring: Browsers and HTML
[5.1] Web Browsers all read HTML (Hypertext Markup Language), a language consisting of a simple set of controls over data. Rather than include graphics and sound files within one file, HTML files include only instructions and text; other elements are called when needed from their resting places in the same folder as the HTML file. With this architecture, HTML files can be quite small and thus transfer quickly over the internet.
[5.2] HTML is basically a labeling language, but has associated scripting and programming languages like CGI, Perl, Java, and JavaScript. These allow for more complex interactions between the browser and the file, and for more interesting Web pages than the standard "static" page available with simple HTML commands. Currently Java "applets," small programs that are compiled and run on the client computer, and Director Shockwave movies are the most common applications used for creating Web pages that combine sound, image, animation, and text. When, as is the case with Director movies, files sent over the Internet have more complex control sections, and use different proprietary command structures, the browser may need plug-ins to run or display them. Director's plug-in is called Shockwave; by using Shockwave from within Director, self-contained file is created which consists of controls and resources (such as images, movies, etc.) that are either placed within the file or are outside and are called when required (like HTML). The Director movie is called from within an HTML file using an "EMBED" command (described below). Linked sounds (.SWA files) and images (.GIF files) do not require a separate HTML file, but currently linked video must be called from within a separate HTML file.
[5.3] Readers running Netscape should look at their plug-ins. Go to the Finder and look inside the Netscape folder for the "plug-ins" folder and look inside at the plug-in programs available. You will probably see Quicktime and LiveAudio, other plug-ins may be downloaded from various places on the Web. In the next section of this paper, you will put the Shockwave plug-in this folder. Back to Netscape, when you install a plug-in it is also necessary to set some parameters in the program. To see these parameters do the following: in Netscape, open up "Options" then "General Preferences" and then helpers. A list of helper applications that call plug-in programs appears; it will probably also include Quicktime and LiveAudio. Click on one plug-in line and then"edit" to see the details: the code names for the application and the file "extensions" or suffixes, such as .mid for Midi files and .dcr, .dir, .dxr for Director. These extensions are very important, as they tell the browser what type of file needs to be interpreted.
6. Shockwave plug-in
[6.1] Director's plug-in is called Shockwave, and it is used to interpret the control codes of Shockwave files, which are identified with ".dcr" suffixes. Before continuing with this article, the reader should get a shockwave plug-in and install it. Go to this URL address: http://www.macromedia.com/shockwave/download and download the plug-in, following instructions. Another address, http://www.macromedia.com/support/shockwave, has answers to questions. The plug-in and supporting files come in a compressed form and require Stuff-it Expander to expand. If you have this program, it will expand the file automatically (or you may have to double-click on the downloaded file). An installer program will appear; quit the browser and double-click on it to install the Shockwave plug-ins. Start up Netscape, and set the .dcr type in Options: General Preferences: Helpers: New. If you don't have Stuff-it Expander, there is a Catch-22 because Stuff-it Expander itself is often presented for download in a compressed state. Here are two addresses to help getting Stuff-it Expander: http://www.aladdinsys.com/consumer/expander2.html, and http://www.aladdinsys.com/support/faqs/mexp2.html.
[6.2] You will need to restart Netscape, but first, increase the amount of memory that Netscape allots,
since the program will now have to open up Director movies as well. Set
the memory to at least 15000 KB (15 MB). Restart Netscape. Go to the Options
folder and increase the cache size
to at least 10 MB. Finally, if you haven't already, extend the window
to the right so that it is as wide as your screen. The accompanying movies
to the rest of this article will appear in a new upper window which you
can move around to be able to see the corresponding text while you look
at the movie or image.
7. Director
[7.1] Director, as the name implies, uses the metaphor of a movie for file creation. A director movie that is itself an introduction to Director is provided here. Go through the movie and refer to it for the following. Each element in the movie, an image, text, sound, or video, is called a "cast member" when it sits in reserve in a "cast library," and a "sprite" when it is actually on "stage"--the screen space allotted for the movie--and part of the action. The sprite corresponding to a cast member is independent and can be altered in many aspects (size, color, etc.), without affecting the original cast member, which acts as a template. Up to 32,000 cast members can be ready for use in a movie (using linked libraries), with up to 120 sprites possible on the stage at one time. Successive events--combinations of sprites--happen in "frames" placed within a "score" which controls the action. Each element, the frame, the score, the sprites, and cast members, can all have scripts or sets of commands associated with them, activated automatically within the movie or by the user. Pre-set scripts called "behaviors" are included, but these can be altered and new scripts written. The user interacts by clicking on sprites, which can be buttons or "hot" spots; as with Web pages, it is possible to indicate to the user where to click by changing the cursor to a "hand" at those places.
[7.2] Director's design gives the author a choice of two levels for creating presentations: 1) using prepared scripts called "behaviors," and 2) writing new scripts. "Script" is a general term denoting a programming language that is created to use common language references, such as "set the text of castmember 'x' to 'I love ice cream,'" rather than the more complex allotment of variables, types, and memory locations found in C or C++ or other similar programs. While easier to use than programming languages, scripting retains certain features, such as "if then . . " and "while" loop constructions, and the "ancestor - parent - child" metaphor of object-oriented programs. Director's programming language is called "Lingo." The standardized behavior scripts allow for application of scripts and interaction without independent programming, but those interested in programming can add their own scripts to govern the actions of sprites, etc. in the course of the movie. Since the behavior scripts have only appeared in the latest version of Director, 6.0, anyone who has used Director has already learned scripting, which was required of the author in earlier versions.
[7.3] Movies with behavior scripts only are generally created manually, using the changing relationships of sprites in the flow of frames implied in the movie metaphor. Cast members--images, text, etc.--are either imported or created within Director, using its Paint and Field tools, and put in a list of cast members, then dragged and arranged on a stage as sprites. Successive movie "frames" are similarly arranged, with a few behavior scripts to create animations. The introductory movie shown above has few scripts, consisting mostly of 1) "wait" type commands, which stops the movie by causing it to replay the same frame until the user clicks; and 2) "go to" type commands that send the movie to a different frame when the user clicks. Another movie with minimal scripting is one I created for a multi-media class at Eastman, with general information on computers and multi-media. The only scripts are "go to" types and "wait until user does something" types.
[7.4] When the movie is run, the frames run sequentially at speeds of 1 to 30 frames per second, allowing for animation or sequences of events similar to a movie reel. In frame-by-frame animation, the frame succession is clear when the tempo, or frame rate, of the movie is slowed. Frames can be looped to wait for user-activated buttons or "hot" spots: these interactive elements allow the user to jump around between frames and control the pace or order of the movie, depending on its design. A simple interactive movie allows users to alternate between images. Simple movies with animation are small, easy to create and compile, and can be found in many places on the Web.
8. Music Analysis on the Web with minimal Scripting: An Example
[8.1] As a simple example of music analysis using a Director movie with minimal scripting, I offer a study of "Los muertos illvan alas de musgo," a madrigal by George Crumb. The Director movie of this analysis was created with 1) a Finale file of the score, which was imported into Director as the notes only, and the staves only, the two are combined in the movie, but having them as separate cast members allows for manipulations (such as coloring) on the notes alone; 2) colored cast members taken from the notes cast member; 3) a separate analytical stave; and 4) a sound file of the song, in this case a performance conducted by the author.
[8.2] The tricky part was to get the scrolling of the score to coincide with the music: the corresponding cast members of the score and notes were lined up and placed in successive frames on the stage to line up approximately with the flow of the music. As the score scrolls by, colored cast members are placed on the score, then moved up to the analytical layer to show the analysis develop in real time. The advantage is that the harmonies (pitch-class sets) are coordinated with colors, and that the student can listen to the score and start, stop, and pause the music and score for study. The scripts are minimal for this movie, which is based on the frame-by-frame succession that is the essence of Director movies, and consist only of restart and pause controls, which are toggled when the user clicks on the stage, and the stop/restart button on the stage.
9. Scripting
[9.1] Scripted movies have the advantage that a small number of elements may be manipulated in different ways by controls in the script, so that the size of the file is smaller than if the elements were copies and manipulated manually. Director's language, "Lingo," is somewhat similar to Hypercard's "Hyperscript" and has features found in many scripting languages. Every element of a movie has a controlling script which may be defined using program "handlers" that begin with the word "on": from the movie itself ("on startMovie"), to frames ("on enterFrame," "on exitFrame"), to cast members, sprites, and interactive buttons and "hot" spots ("on mouseUp," "on mouseDown"). In addition to the program handlers provided within Director, users may write their own handlers, which are similar to "functions" in programs like C and Pascal, and either perform a task or take a value, change it, and return a value. Variables may used locally, or defined as "global" and used in different handlers.
[9.2] The script of Lingo can be divided into at least nine categories:
1) decision scripts: mathematical symbols, numbers, operators such as "=" or "<>" (not equals); "if - then -- else if - then -- else" loops; "repeat while" or "repeat with" loops.
2) function scripts: handlers which perform a task, or take a value, perform an operation, and return a value.
3) classification scripts: define local variables, global variables, lists, put and set commands which assign values.
4) control and program handler scripts: scripts that run the program and connect with the computer, such as abort, exit, start, alert, mouseDown, KeyDown, button scripts, menus, sorts.
5) location scripts: setting the location of "sprites" on the stage: top, bottom, right, left, location of mouse when clicking on stage.
6) attributes scripts: setting other attributes of elements than location: color, blend, height, number, name, type.
7) text-related scripts: identifying characters, words, lines, whether text field is editable by user, length.
8) connection scripts: connecting to other programs, files, desk accessories, resedit manipulations, Xlibraries, File Input/Output (I/O), etc.
9) creation scripts: object-oriented programming elements: ancestors, parents, children.
10) Web and network-related scripts: controlling Web and networking features.
10. Teaching Music Theory with Director: A Scripted Example
[10.1] A typical freshman homework
assignment using a scripted Director movie is given, with the first
eight bars of Schubert's Moment Musicale op. 94/6 as the passage. The movie
involves 1) the use of a notation program such as Finale to notate the musical
passage, a reduction of the passage as the answer (if desired), and a blank
stave of the same size as the reduction for the students to enter their
answers to a counterpoint-type question; 2) a Roman Numeral, Arabic number,
and note head repository for analysis; 3) color flags and text field to
label non-chord tones; and 4) a sound file of the passage, the movie includes
a sound file of the outer voices for the answer. For the first question,
the passage appears on the stage, and the student can first listen to the
passage, then arrange Roman Numerals and Arabic numbers in the proper place,
and then move color flags over non-chord tones and label them. For the second
question, on a blank stave, the student can arrange notes and numbers to
show underlying counterpoint and/or a reduction of the harmonies. When done,
if desired, the student can check the answer. To "hand" the assignment
in, the student makes snapshots of the screen (command-shift-3 with any
Macintosh after Operating System 7.01) showing the answer to question 1
then question 2; the snapshot saves a picture of the screen as a PICT file
to the desktop. The student then labels the two pictures with his/her name,
and puts them in a homework folder.
[10.2] A non-working version
of the movie showing the separate elements is included. To create the
movie, the main cast members, the score and staves, are exported from Finale
as PICT files (an image format that Director supports). First, import the
files into Director as cast members, and size the stage at 432 X 455 pixels
(for a 17 inch monitor, 464 X 310 for 15 inch). For Question 1, put the
notation cast member on the stage. To create the Roman numeral, Arabic number,
and note repository, use "fields" and type in the numerals and
numbers, but use "texts" for the quarter note heads and sharp,
natural, and flat signs(using a font like Petrucci). "Fields"
are more flexible, but require that the user has the same fonts as the author--so
they should be set up so that the font doesn't really matter; "texts"
are treated like bitmap images so the user won't need the Petrucci or other
notational font. To complete the cast, using the Paint tool, make a small
colored circle to use for non-chord tones. Arrange the Roman Numerals and
Figures and symbols on the stage. For each sprite, check the "moveable"
box so that the user can move the symbol. Create a field for the student
to add the names of non-chord tones, and fields explaining what the student
is to do. Finally, add navigational buttons, to move to different frames.
When allowing for interaction, use "go to the frame" in the frame
script, as this allows the movie to keep running and accepting mouse clicks
etc. (the use of "pause" stops the movie). For Question 2 and
the answer, follow a similar procedure.
[10.3]A working version of the movie showing its scripts is also included -- the main "movie" script is given in the top right hand field. The scripts showing in the field change according to what sprite is clicked. This field may be moved by dragging with the mouse.
[10.4] When scripting a movie, it is easiest to place all handlers in "Movie" scripts, under a general "global" line, so that the global variables are available to all handlers, with calls to the handlers in the scripts of the various corresponding sprites, frames, etc. This avoids the common problem of undefined global variables--a situation which causes errors not always clearly articulated by Director's automatic de-bugging features. The "Movie script" sets up several groups of variables, beginning with "HI, HII, etc." which are variables set to the initial locations of many sprites (necessary for the script when they move and recreate themselves as the user performs the analysis). The next variables (scroll down in the upper right hand box to see these) are for two lists, then for counters also used in the move/recreate scripts. Global variables for the sound follow. The "on startMovie" handler sets up the initial values for locations and counter global variables. It also initially sets all sprites visible, as some are made invisible in the course of the movie, but toward the end another handler called "nonvissprites2" makes the sprites corresponding to question 2 invisible, since the user will presumably start with question 1. (If the user goes to question 2 first, a script along the way will make the relevant sprites visible.)
[10.5] The essential script for all the moving sprites (the Roman numerals, etc.) is "newObject," placed within the movie script. Move one of the Roman Numerals to show this script. The "if .. then" script is a test: if the sprite has been moved from its original location, then it will not duplicate itself; this is so that users can adjust the Roman Numerals, etc. they have already placed in the score. If the sprite has not been moved, then the script is invoked. This script assigns the cast member clicked on to a new sprite, so that there is an apparently endless supply of numerals and figures. In fact, the "duplicate" replaces a "dummy" sprite that is sitting unnoticed on the stage, starting with sprite 120 and moving backwards by the incremented value of a counter variable "x." There is a total of 120-(the number of functioning cast members) of these dummy sprites, allowing for around 60 copies of the Roman Numerals, etc. The script places the duplicate at the same place as the original, while the original is free to move away.
[10.6] The trick in the script is to duplicate the cast member (the Roman numeral, etc.) only the first time the sprite is clicked -- after it is moved, the user should be able to move it again without creating another duplicate. As noted above, this is the purpose of the location test beginning the script in each of these moving sprites. If the sprite is at the original location, it will create a duplicate; if it has been moved once, it will not.
[10.7] The handler "newObject" thus changes some sprite attributes, and sets the new sprite so that it is movable on the stage and so it has the same "ink" or image qualities as the original. When changing any sprite attributes, it may be necessary to end the handler with "upDateStage" or to use "go to the frame" in the frame script to register the change--this movie uses the latter.
[10.8] The new sprites replace dummy sprites that have been put in all frames of the movie, since there is no way to anticipate the order in which students will do the questions. Thus, "visible" sprite handlers, "vissprites1" and "nonvissprites1" and "vissprites2" and "nonvissprites2" are added. To see these handlers, click on one of the navigation buttons: "question 2" or "Answer." The "vissprites1" and "nonvissprites1" handlers set the sprites corresponding to question 1 visible or invisible, while the "vissprites2" and "nonvissprites2" handlers set the visibility of the sprites corresponding to question 2. Two lists are created to catalogue the sprites from these two questions: Q1List and Q2List. At the end of the "newObject" handler, the duplicated sprite number is put into the corresponding list, and the numbers in the list are used in the "visible" handlers. These handlers also include the sprite numbers corresponding to the original movable sprites (the Roman numerals, etc.), which also must be made visible or invisible, as the sprites of Question 2 must appear in frame 1 to set locations.
11. Streaming Audio
[11.1] Director movies may also include sound files. With Director on the Web as Shockwave, having relatively large sound files embedded in the program causes slow download problems. One solution is to use Macromedia's streaming audio format, which comes with an efficient compression of at least 6:1. Using this compression, sound files embedded in the movie are smaller, and can be used normally. When files are still quite large, it is also possible to link to external sound files and play them during the movie. This is the technique in the assignment analysis movie: the sound is played with the "Listen" button, which activates a specially prepared compressed sound file, "schubert.swa," that sits outside the movie and is called when needed. The handler is set in the movie script, and the sound is called by the button script, with the handler "playswa." With this streaming audio, a buffer is created and the downloading sound file is played when the buffer is full, generally about 5 seconds. As the file continues to download, it simultaneously plays.
[11.2] Returning to the homework assignment, to complete the steps for creating the movie, prepare a sound file of the passage, using a program like Sound-Edit 16 (also made by Macromedia), to create a mono file, 16-bit and 22050 samples. Use the SWA Compression Xtra in Soundedit and the SWA Settings Xtra for Director to compress the sound. The sound is given a corresponding dummy cast member, called "SWAHolder," and the name of the sound file is assigned in the "on startMovie" handler. The sound handlers then take this sound file and play it, with a few configuration features. The sound can be heard any number of times by pressing the corresponding button. A second sound in this example is a reduction to the two outer voices. Both of these sounds were created first as Midi files, then altered to .AIF format sound files using Quicktime's MoviePlayer, then Sound Edit 16 to change the sounds into compressed .SWA files.
12. More on Shockwave: Web Programming
[12.1] Shockwave, both a process and plug-in for putting Director movies on the Web, was introduced in October 1995, and is available for Windows or Macintosh computers, and for Web browsers Netscape Navigator and Microsoft Internet Explorer. Since Shockwave introduces a new MIME type, .DCR, the server must be configured, and the client browser must be configured with the plug-in and helper type (as discussed above). To create Shockwave movies, Director uses Xtras contained in folders called "media," which contain Xtras related to streaming audio, and "net support," which contain Xtras related to shockwave movies on the Web. Director 5.0 had an Xtra called "Afterburner" to create shocked movies, but Director 6 has a built-in "Create Shockwave Movies" choice in the file menu, which creates a file ending with .DCR. Shocked movies are placed within HTML documents. The basic EMBED tag is: <EMBED SRC="movieName.drc" WIDTH=widthInPixels HEIGHT=heightInPixels>.
[12.2] The first rule of Web programming with Shockwave is to start with the smallest movie possible: if the movie is large, divide it into smaller movies that call one another, or begin with an introductory movie that consists of only an image which displays while other movies load (using the GoToNetMovie script). The second rule is be clear on pathnames and file names. Director's lingo, the pathName, is disabled in Shockwave, and the movie and supporting files all need to be in the same folder or directory and properly labelled. Files names have different restrictions on different platforms: UNIX servers are case-sensitive; Windows machines may have trouble with names longer than eight characters with a three character extension or names with spaces. These two and MacIntosh may have trouble with special characters in file names.
[12.3] As with sound, color and graphics are complex topics unto themselves when it comes to size, quality, and compression. The safest route is to use the System Color Palettes and the smallest bit size for images that provides a clear image: the difference between 8 bit and 16 bit color is noticeable, but the former is acceptable. Use text fields if possible, with standard fonts: the client computer must have the same fonts to get the same text shape and size. Director automatically substitutes between standard MacIntosh and Windows fonts. Text created in the "text" cast members is bitmapped and takes more space, but the client does not need the same fonts, and so the effect can be assured.
[12.4] When putting Director movies into shocked form on the Web, important considerations are: 1) data transmission rates; 2) New Lingo commands; 3) Director features disabled; and 4) miscellaneous issues that affect playing Director movies in a browser. Data transmission on the Web is, from a hardware point of view, standardized, with user modem speeds of 14.4 kilobits (Kb) per second (= 1.8 KB/s), 28.8 Kb/s (3.6 KB/s), 33.6 Kb/s (4.2 KB/s), and 56 Kb/s (7 KB/s). Higher speeds come from ISDN lines, ranging from 64 Kb/s (8 KB/s) to 1.5 Megabits (Mb)/s (184 KB/s), and T1 lines at 1.544 Mb/s (193 KB/s), Ethernet at 10 Mb/s (1.25 MegaBytes (MB)/s), and T3 lines at 44.736 Mb/s (5.592 MB/s). Over the internet, however, these theoretical speeds are affected by the data transmission capacity of server computers and by how busy the server and the lines between server and client are at that moment--a very unpredictable value. A given speed estimate for general use is about 1 KB/s. By taking the size of the movie and supporting files, approximate download times can be calculated. The most important advances for data transmission are streaming versions of data: Shocked movies and audio are both streaming, but streaming video is not incorporated into Director, although Quicktime movies, which are linked to from within shocked movies, are now streaming.
[12.5] Other concerns to users of Director are the features not available in Shockwave form, and the new Lingo scripts required by Net form. Features not available are mostly those related to operating systems: custom menus, printing, saving, restarting, resources, file I/O etc., but also include movies within windows. The Web-related Lingo commands are in three categories: those that start a process, those that monitor it, and those that send or receive a result once the process is done. This three-step set-up accommodates the essentially asynchronous Internet, where the time to send and receive data is unpredictable. Finally, a concern at all times on computers is the amount of free memory: Shocked movies on top of Web Browsers take up enormous resources, and the use of multimedia files can easily (on the MacIntosh at least) cause system crashes. While new versions of operating systems and internet protocols help this situation, it is always a concern when sending large and complex files over the Web.
13. Conclusion
[13.1] As I noted at the outset, the availability of powerful computers linked on the Web offers many possibilities, but also pitfalls. The most basic opposition here is technique versus content. It is easy (remarkably easy!) to become absorbed in the how rather than the why and what when working with computers. This situation is the result of many factors. First, although the Web is meant to be platform independent, in reality, each of the major systems, from Apple, Microsoft and the IBM clones, Sun, and SGI, have their own characteristic ways of interacting with the Web. Thus, authors must learn different programming languages and codes. Currently, for instance, Microshoft has its own brand of HTML, different for its browser, called Internet Explorer, than that used on the browser, Netscape Navigator, so that some web pages or features cannot be read by both programs. Although Director is useful since it's Shockwave movies are playable on MacIntosh or Windows machines, in the latter case, users must have "sound cards" properly installed and overcome some difficulties in the "plug-and-play" features to hear musical files. As well, servers are often Unix based machines. In my own efforts, I discovered that, while upper case or lower case letters in file names and links are equivalent on the MacIntosh, on the UNIX server a reference to a file with a different configuration of lower or upper case letters failed to find the file, and I had to redo some links and code.
[13.2] Second, since in the marketing of computer programs, prices must go down with successive generations of more powerful systems, companies dole out "versions" of software yearly that users are required to purchase to keep up. Although Director is useful, for instance, the initial cost is high (around $800) until the educational versions come out, usually a year or two later. The educational version of Director 5, for around $75, was available only a few months before Director 6.0 came out. After the initial outlay, while upgrades are not too expensive, the price dissuades many authors. In my case, I learned the Shockwave version of Director 5.0 by cobbling together elements from books and the Web; in Director 6.0, these elements have been integrated into the program--but with some elements now changed from the "Afterburner" generation. Such changes make working in multi-media exasperating.
[13.3] Third, to create worthwhile educational content for the Web, instructors have to re-imagine their course material, or invent new courses, appropriate for the new medium. Putting class notes and schedules in electronic form is convenient, but hardly represents a new use for computers. What is the criteria for useful Web texts? At Eastman, only a relatively small proportion of students have web access, so it is difficult to do tests with large groups. I have just begun to use web pages in my own teaching, but in the process of thinking about using the web and computers, a few important questions have come to mind and, I believe, need to be considered by all web authors for educational materials:
1) Do the materials use the capabilities of the computer to combine sound
and image?
Image and text alone work quite well in a book, and sound alone is easily
available on CD systems. Combining images and text, with instant access
to both, is a strength of the computer, and should be the goal of instructional
materials.
2) Are the learning materials goal-directed?
I'm not a big fan of pages full of multiple menu possibilities on successive
pages or teaching materials organized like a game. Part of teaching is instructing
students in a systematic and goal-oriented way, as their lack of experience
with the material is the reason they're in the class to begin with: it is
not appropriate to assume that they will make the best decisions in the
order of material. Web materials should be efficiently and clearly presented,
with the next step indicated.
3) Do the assignments or tasks on the Web allow students to learn at
their own pace?
This question requires a well-thought out interface, with lots of looping
connectors so that students can go back over material and review/rediscover
ideas and concepts as needed. This potential is also one of the great strengths
of the computer.
4) Does the program or file point beyond itself, causing the student
to make larger connections?
Self-contained drill type programs might be of some use in a directed environment,
but the ideal materials should both present the immediate topic and point
(with links) to topics of larger implication.
[13.4] To the problems of multi-media authoring noted above--learning programming languages, Web pages, problems with multiple platforms and generating sound--Director offers an all-in-one solution, and is worth consideration by all those interested. Although it has a few quirks, Director is relatively easy to learn and get fast results with scripts. (Here is a list of resources for more information on Director and Shockwave.) As for the often frustrating and time-consuming process of developing content for the Web, Director can help with the technique, but the content--from imagination and an understanding of the medium--is the result of hard work and time spent in the environment. As operating systems and programs become ever more closely tied to the Web, with teaching and learning in the education business inevitably following, all of us will need to use computers in the most efficient and effective ways possible.
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