VARMINT'S AUDIO TOOLS VERSION 0.41 (beta) Sound Blaster programming library DISCLAIMER This software and documentation is provided as-is and is not garanteed to do or be anything. Use at your own risk. INTRODUCTION Varmint's Audio Tools (VAT) is a small Sound Blaster programming Kit. It's primary feature is a DSP interrupt driven core that handles real-time mixing and playing of digital sounds and background MIDI music. It also supports many FM chip routines and input functions for WAVE samples and MIDI music files. Auto recognition and setup of Sound Blaster compatable cards. 4.5 (adjustable) millisecond clock and microsecond accuracy timers. VAT is Freeware and comes with source and example code (Turbo C). VAT was adapted from Peter Sprenger's SoundX library. Peter's library was the only sound blaster library that I could actually get working out of the half dozen or so that I ftp'ed from x2ftp.oulu.fi. It is a pretty nice library, but the documentation is lacking and the code still has a few flaws, so I decided to find out how it worked and then modify it to fit my needs as a novice Sound Blaster Programmer. Peter has given me personal permission to distribute this library and I want to offer my special thanks to him for his effort and the information he has provided. SO WHO NEEDS IT? VAT is intended for any programmer who wants to add sound effects and music to their programs quickly and easily. Like so many other programmers, I've been very dissappointed by the sound library offerings out there. I have designed VAT to be very easy to use and as versatile as possible, and I hope that it is useful to you. When dealing with routines that run inthe background, most programmers are concerned about how many CPU processing cycles the routines use up. Here are the numbers that I get on my 486 DX2/66: Base overhead: 1.5 % Midi overhead: 1.0 % (average) Sample overhead: 1.35% per sample So, let's say that your program is playing some midi music and 4 digital samples in the background. The total overhead would be: 1.5% (base) + 1% (midi) + 4 * 1.35% (samples) = 7.9%. That means that if you were animating some graphics at 30 FPS, it would slow down to 27.6 FPS. Pretty acceptable. BETA VERSION This is the beta version of VAT, so it is a little scant on documentation, but I have tried to make up for that by commenting the code heavily and providing an example program. HOW TO CONTACT THE AUTHOR(S) Any suggestions or bug reports are very welcome. (I've included the file "survey.txt" to make this process easier you.) Please send them to one of these email addresses: smeagol@rt66.com ejorgensen@rr5.intel.com Peter Sprenger can be reached at: Pete@amber.dinoco.de FREEWARE VAT is freeware, so you are free to copy and distribute this library as much as you like as long as you charge no fee for it's distribution. You are NOT restricted, however, from charging money for games or other programs that use VAT to produce sound. All I ask is that you send me a complimentary copy. (Peter Sprenger would like one too.) This helps me as a developer to know who is using my software and for what. It is also a good way to make friends! In other words: Q: Can put any of the programs or example code from VAT into my own shareware that I am going to sell for money? A: Absolutely not. Q: If I use VAT to generate sounds in my game, can I sell my game for money? A: Yes! (Please send Eric Jorgensen and Peter Sprenger complimentary copies of your game!) FEATURES - Background DMA digital playback with real time mixing and unlimited channels. - Background Playing of MIDI music with easy control of tempo and volume. - Routines to access the FM chip. - 4.5 millisecond (adjustable) clock plus microsecond accuracy timers. - AUto recognition and setup of Sound Blaster or Sound Blaster compatable sound cards. - Does not disturb the system clock (does not use int08) - Comes with heavily commented source code and demo. - Comes with an FM voice editor VARMINT'S HOME FTP SITE I have a home site for all of my software: mack.rt66.com:/users/smeagol Here you can find my other shareware and freeware offerings: tmkr11.zip Terrain Maker - A random Terrain generator/ editor for the freeware raytracer Persistence of Vision (POV). vpova10.zip Varmint's POV animator - A POV scene file parser that allows the inclusion of functions and animation commands. svgadiag.zip Free SVGA diagnostic utility survey_results.txt Compiled results of a large survey of SVGA cards that I performed in December of 1994. -----------------------------<*>---------------------------------------- VOICEED.EXE - The FM voice editor This is a simple package to make editing FM voices a little easier for you. To use it, you will need a VGA capable graphics card and a mouse. The interface is fairly simple and should be self-explanatory. Here is some lame, rudimentary documentation: To change the name of a voice or a filename, just click on the text and the program will let you type in a new name. To toggle a radio button, just click on it. To operate a slider, either click and drag the slider tool with the mouse or click on the arrows on the sides. (The arrows move the slider one unit.) Highlighted letters on butons are hot keys. A button can be accessed from the keyboard by pressing the hotkey letter. Be sure to save the file before you quit the program! More documentation will show up in version 1.0. -----------------------------<*>---------------------------------------- USING VARMINT'S AUDIO TOOLS: A CRASH COURSE Compiling the source code: The sound routines are desinged around FAR or HUGE pointers, so you need to compile under a large or huge memory model. If you are using Turbo C and you wnat more memore under the debugger, you can request more by selecting "Debugger" from the options menu. Starting up the interrupt core: #include "sound.h" main() { if(SB_Setup()) { Go_Varmint(); // THis starts up the background handler // and enables you to play sounds and // MIDI music. do_some_stuff(); Dropdead_Varmint(); // THis removes Varmint's interrupt and // puts the regular system clock // interrupt back. } else { printf("You don't have a sound Blaster. EGAD!"); } } *** IMPORTANT ****** IMPORTANT ****** IMPORTANT ****** IMPORTANT *** - Do not call Go_Varmint() if SB_Setup() fails. - If you call Go_Varmint() and your program breaks or crashes before Dropdead_Varmint() is called, you should reboot your computer, or you might get a system crash next time you run your program. - If you call Go_Varmint(), you MUST call Dropdead_Varmint() before your program exits. If you don't, you might not be able to run your program again without rebooting the system. - As a general rule, you should only have one Go_Varmint and one Dropdead_Varmint() in your code. *** IMPORTANT ****** IMPORTANT ****** IMPORTANT ****** IMPORTANT *** Playing Sounds Once Go_Varmint has been called, you are free to play sounds. You will first need to load the sound (11 Khz, 8bit mono WAVE format.) and stick it onto a type HUGE pointer. (You can use the function SetRate() to change the playback rate of the sounds. See information about the global variables vlcok and dma_bufferlen below.) void somefunc() { unsigned char huge *sounddata; unsigned long int sound_length; sounddata = loadwave("shwoop.wav",&sound_length); if(!sounddata) { printf("Error loading wave."); exit(0); } playsound(sounddata,sound_length); } You only have to load the sound once, and since playsound() handles things intelligently, you can call playsound() as many times with as many different samples as you want without having to worry about conflicts. playsound() will not cause any problems if Go_Varmint() has not been called, but it won't play anything, either. :) Playing MIDI files To play a midi file, you don't actually call a funtion, but you instead set values to a few global variables. unsigned char inst[1][11] = { 0x03,0x01,0x80,0x80,0xF7,0xF7, 0x13,0x13,0x02,0x01,0x03}, // Harpsichord void mididemo(void) { int i,j,k,err; char *errstring[256],r=0; static MIDI *bach = NULL; FM_Reset(); for(i = 0 ; i < 9; i++) { // Set up FM voices FM_SetVol(i,0); FM_SetVoice ( i,inst[0]) ; } // load a midi file err = ReadMidi("bach.mid",&bach,errstring); if(err) { printf("MIDI read ERROR: %s\n",errstring); printf("Exit?\n"); r = getch(); if(r != 'n') exit(1); } midi_data = bach; // assign the music midi_reset = TRUE; // reset internal midi variables midi_on = TRUE; // Turn on the midi player now! } You can adjust the volume by changing the value of the global variable "music_volume". (Min = 0, max = 63, default = 50) You can adjust the tempo by changing the value of the global variable "midi_usertempo". (default = 2.0, 0 = fastest 50.0 = come back wednesday) See also information about dma_bufferlen and midi_tempoadjust below. Voices can be altered while a song is playing without any problems. Miscellaneous Functions and Variables extern unsigned _stklen I was getting random reports with older version of the library of stack overflow errors and system crashes. I turned on the stack checking option on my compiler, and what do you know, the sound code started crashing! I traced the problem to sb_int(). It only crashes when it tries to call external functions. By all appearances, I should only need about 1K of stack space, but I had to increase it to 8K to make the problem go away. If you can explain this behavior, by all means, drop me a note! void SetRate(int rate) This function allows you to dynamically change the playback rate. Changing setrate will affect the frequency at which vclock is incremented. It will also affect the midi playback tempo. long int vclock This isn't a function. It is a global varibable that contains the current clock tick from the sound handler. The frequency at which is incremented can be calculated like this: sample_rate / dma_bufferlen With library default settings, this is every 5.45 milliseconds. long int dma_bufferlen This is another global variable, and it controls the size of the DMA mixing buffer. The default is 60 bytes. If you want to change this number, you should do so before you call SB_Setup() By making this number bigger, you will lower the frequency that sb_int is called. You might want to do this if you think the sound routines are messing up some other time sensitive functions those that look for the VGA verticle sync. If you increase dma_bufferlen, bbe sure to increase midi_tempoadjust by the same ratio, or your midi flies will play at the wrong speed. float midi_tempoadjust This global variable changes the midi tempo by reducing the delay time between notes. The default value for this is 2.0. Bigger numbers make the music faster. You should only have to mess with this number if you cahnge the value of dma_bufferlen. WORD DSP_overhead This is another global variable. It always holds the number of clock ticks that elapsed during the most previous sound handler interrupt. To get the overhead ratio, divide this number by 6000. void timer_on() WORD timer_off() This a hyperaccurate suit of timer funcs. Start by calling timer_on() and the read the result from timer_off(). Each tick is about 0.838 *micro*seconds. These functions are only good for measuring times shorter than about 50 milliseconds. msdelay(int milliseconds) Standard millisecond delay function. I mention this becasue VAT seems to cause problems with the delay() function included with Turbo C. void load_instruments(char *filename,BYTE inst[128][11]) This loads 128 instruments definitions from a file of your choosing. void freemidi(MIDI *m) I added this function for convenience. It automatically frees the a midi structure and the tracks inside it. A FEW WORDS ABOUT MIDI The MIDI standard specifies that a midi compliant instument needs to have something like 24 voices available for playback. Since the Sound blaster FM chip only offers 9 (even less if you implement percussion), You should be wary of playing midi files that play more than 9 voices simultaneously. Here are some general tips: - use midi files that have only 5-6 voices max. - Unless you implement rythm voices, chop off the rythm track with a midi editor. COMING SOON Better docs! New functions! MOD support OPL MIDI ouput Cooler Demo! -----------------------------<*>---------------------------------------- Here is a note from Peter Sprenger's SoundX library: ------------------ Pete@amber.dinoco.de Why I made this library: I was myself in a search of a good library for soundblaster programming. What I encountered was the SBF, that was a nice idea but written in a such a hurry, that it was still useless. I has still bugs, too. Some other packages looked interesting but are quite expensive. I just bought the original SBK from Creative Labs and was disappointed. It was expensive and bad! In their design I lost control of Timer 0, that I needed for my other programming. So I decided to make a good freeware soundblaster bibleothek. Up to now I spent about 200 hours working time in this project. It is my hope that their will be other people who make freeware that can be used. If every programmer would spend about 100 hours for freeware in the lifetime, not everybody had to reinvent the wheel again. Look at the guys from GNU and OSF they are doing a great job! If you can use this routines use them! There must be non false shame. I wrote this stuff that not everybody has to write his own routines. But it would be nice, that when you make something commercial with my routines, that you send me a copy of your project or send me some bucks, just enough for pizza and coke to support my night programming sessions. If you send me nothing, ok. But USE the stuff, if you can need it! Have fun with SoundX, Pete Germany, 27-Jun-93 ------------------------------------------------------------------------