My involvement with the Engineering Department at WITR, (the campus radio station at the Rochester Institute of Technology, Rochester NY), had me searching for a digital replacement for the station's 'cart' system. Most of the systems available were extremely expensive, Intel PCbased and/or used a proprietary operating system and hardware. (i.e. the infamous DigiCart). I realized that all we really needed was a system that could play 16 bit, CD-quality sound files in real time from a very large hard drive or hard drives and software to handle hard drive back ups and sequencing the items to be played. Again I realized that these tasks would be simple and inexpensive to achieve with the Macintosh and its operating system.
•Most new Macs come out of the box with 16 bit stereo audio in and out.
•Off the shelf hard drives and back up software is readily available. Built-in ethernet opens up the possibility to network between studios.
•The operating system supports a vast array of sound tools simplifying the task of writing software to handle the sequencing of items to play.
MacAssist is a programming project I decided to undertake near the end of Spring 1994 to perform the sequencing needed for "Live Assist" radio. MacAssist allows the user to select items to be played (AIFF files in this version) from a specific group of folders set up ahead of time. This way the DJs don't need to navigate through folders to get to the items they want to play; only folders of interest are displayed. Items may then be played immediately, assigned to one of four hot keys (played when the button is pressed) or added to a play list. The play list is a queue of items to be played sequentially. Once you start the cue playing, the software takes care of seguing from one item to the next; just sit back and watch the queue timer count down. For each item the user can define default times for overlapping between the previous and next item. Breaks can also be added to the queue to stop the sequence between items. Play lists can be saved and loaded again later. The number of items that can be playing simultaneously is limited by processor load, hard drive speed and memory available. MacAssist has no problem running in the background.
Installation
A few warnings...
Currently, MacAssist does NOT check with the Gestalt manager to make sure your computer has the required hardware or system software to run. If you are running system 7.1 or later with the sound manager 3.0 or later, and your computer has the Apple Sound chip you should be fine.
When the software encounters an error, (i.e. file error or too much processor load to start another sound), it will not notify the user. Instead it will simply fail to do what it was asked to do. (i.e. save a play list or start another item playing). I hope to correct this in a later version.
Now the installation...
1. Run the MacAssist application.
2. Set up where the application looks for sound (AIFF) files.
-Under the FILE menu, select FOLDER OPTIONS and the ADD FOLDER submenu item
-Use the SELECT button in the folder dialog box to add the desired folder to the applications folder list.
-Repeat for all folders you would like to access from this program.
-Under the FILE menu, select FOLDER OPTIONS and the SAVE FOLDER PREF'S sub-menu item. Next time you run MacAssist on the same computer, the folder settings you just saved will come up by default.
NOTE: Folders can be on any hard drive or network drives. The application will attempt to mount the drives which contain the default folders when it starts up.
Disclaimer
The author is not responsible for any damages caused, directly or indirectly, bythe use of this software.
Operation
The best way to understand MacAssist is to use it. The main dialog box has four areas of interest. The first is the file area on the top left. This is where all the sound files in a given folder are displayed. The name of the current folder is shown on the pop-up menu on top of the list. Use this menu to switch between folders. To add or remove a folder from this menu, use FOLDER OPTIONS under the FILE menu. When you select a file from the list, three buttons under the menu become active: PLAY, HOT KEY and ADD. Clicking PLAY will start the file playing, Clicking HOT KEY will bring up a dialog box asking you which on of the four keys to assign it to, and clicking on ADD will add the file to the play list
Next is the Play List area. Files you have added will appear in this list in the order they will be played in. If you select an item in this list, you can delete it using the delete key. If you open a play list, or add an item from the file area, it will be inserted before the item you have selected, otherwise the list you opened or item you added will be put at the end of the list. Remaining time shows you the time to the end of the list or the next break. The START and ADD BREAK buttons at the bottom are self explanatory.
The Playing area, near the bottom of the dialog box, is a list of items which are currently playing. Each item has a pop-up menu associated with it which allows you to control the item. Play, Pause and Stop are self explanatory. Recue will stop an item from the play list and put it back in the beginning of the list. Fade To Next fades the item out in four seconds and if the item is from the play list, starts the next item in two seconds.
The last area is the Hot Key area at the very bottom. Pressing any one of the button will start playing the item assigned to it. Use the above mentioned HOT KEY button in the file area to assign items to the keys.
The final item that requires explanation is the SET ITEM TIMES item in the FILE menu. you can add special information to any AIFF file that will control how the file will behave coming out of a previous item playing and going into the next (via the play list of course). When you choose SET ITEM TIMES, you will be asked to select a file. Then you will be shown a dialog box that tells you the total time for the file you have selected and allows you to set a two different times.
If the second time (right most) is set to 0:10.0, the next item will start playing ten seconds after this item was started. If the first time (left most) is set to 0:05.0, this item will start five seconds before the previous item would have started it. You can also add a comment to items in this dialog box. The comment will appear with the item name when it is playing. Selecting SAVE will embed this information into a application specific chunk of the AIFF file, making it the default every time the file is used by MacAssist. Other applications ignore this information since the application chunk has a signature that identifies it as belonging to MacAssist.
Bugs and Future Versions
The playing of sound files in MacAssist IS preemptive (interrupt driven) and should not glitch while the computer is off doing other things. However... the triggering of the next item in the play list is cooperative, (does not occur during an interrupt due to a limitation with the current version of the sound manager), and will not occur if you are doing certain things that make the Mac not very cooperative. This means that if you are in a modal dialog box (like the open file dialog) or are in a menu when an item should start playing, nothing will start until you leave the box or menu. A good hint that the Mac is being uncooperative: the remaining time clocks stop counting.
The code I am using to check and conver the time strings entered in the time boxes (in the SET ITEM TIMES dialog) to long type numbers is not very robust. In this version, make sure you are entering valid times. If you do not... well, lets just say I make no promises!
Also very important: DO NOT insert a floppy into any drive while a sound is playing! For some reason Apple saw it fit to make disk insertion a very high priority interrupt. So when you insert a disk, all other lower priority interrupts (like sound for example) are kept on hold until the disk insertion is finished being handled.
In the future I would like to implement looping and previewing as well as support for multiple sound output devices (to allow previewing through another set of speakers while other things are playing). I also plan to make MacAssist Apple Scriptable so it may be controlled remotely from another machine on a network. I would like to add support for AIFC files (AIFF with compression) and the ability to open sound input devices as an item to be played. The ability to change item times on a one shot basis, from the current play list, and save them with that play list would be nice too. Most importantly, I would like to build an interface to connect the Mac to the start and stop buttons found on every broadcast console so the play list can be triggered from the console. It's a bit to soon to add the other cool ideas I have.
Ye 'ol Shareware message
MacAssist 0.1 beta is shareware. You are free to distribute it, unaltered, provided that this documentation remains with the program. If you find MacAssist useful, please send $20 to the author at the address below.
Ethan Funk
44 Alfie Drive
Rochester, NY 14623, USA
If you have comments, questions or suggestions, I’d love to hear from you. Even if you don't pay I would be greatly encouraged by your feedback. Please drop me a line!
If this software is being used at another collage radio station or (Yeah, right...) one of those businesses that make money by hooking a jukebox to a transmitter, (better get rich now because Direct Broadcast Satellite is just around the corner, guys)... I'd really, really like to know.
I can also be reached via Internet E-mail: eaf2239@rit.edu
