Lesson 06
Adding Sound
How to use libmad to play MP3 files in your programs.
This page is the second page of a lesson written by guest writer Stephen Merity (aka Smerity). If you have stumbled upon this page without going through the first
part, go back and start from the beginning.
And now on to what I like to call the twilight zone. I call it that because at this moment, I have no clue how it works or why, but I do intend finding out some day. Anyway, these functions are necessary for your code.
Next up is part three where we'll continue building our program.
And now on to what I like to call the twilight zone. I call it that because at this moment, I have no clue how it works or why, but I do intend finding out some day. Anyway, these functions are necessary for your code.
// TWILIGHT ZONE! <do doo do doo>
/* Exit callback */
int exit_callback(int arg1, int arg2, void *common) {
sceKernelExitGame();
return 0;
}
/* Callback thread */
int CallbackThread(SceSize args, void *argp) {
int cbid;
cbid = sceKernelCreateCallback("Exit Callback", exit_callback, NULL);
sceKernelRegisterExitCallback(cbid);
sceKernelSleepThreadCB();
return 0;
}
/* Sets up the callback thread and returns its thread id */
int SetupCallbacks(void) {
int thid = 0;
thid = sceKernelCreateThread("update_thread", CallbackThread, 0x11, 0xFA0, 0, 0);
if(thid >= 0) {
sceKernelStartThread(thid, 0, 0);
}
return thid;
}
// END OF TWILIGHT ZONE! <do doo do do>
Now onto the main section of your code. First thing we will do is set the PSP's clock speed to full. Please note that this will not damage your PSP in any way, as it has
only been underclocked to this speed by Sony, the reason was most likely battery life (for more information, see Lesson 05.
Another notable addition is the "pspAudioInit()" function. This is similar to the "pspDebugScreenInit()" function that we have always called. Basically, it sets up the speakers
and everything to be ready to handle our sound output.
/* Exit callback */
int exit_callback(int arg1, int arg2, void *common) {
sceKernelExitGame();
return 0;
}
/* Callback thread */
int CallbackThread(SceSize args, void *argp) {
int cbid;
cbid = sceKernelCreateCallback("Exit Callback", exit_callback, NULL);
sceKernelRegisterExitCallback(cbid);
sceKernelSleepThreadCB();
return 0;
}
/* Sets up the callback thread and returns its thread id */
int SetupCallbacks(void) {
int thid = 0;
thid = sceKernelCreateThread("update_thread", CallbackThread, 0x11, 0xFA0, 0, 0);
if(thid >= 0) {
sceKernelStartThread(thid, 0, 0);
}
return thid;
}
// END OF TWILIGHT ZONE! <do doo do do>
int main() {
scePowerSetClockFrequency(333, 333, 166);
pspDebugScreenInit();
SetupCallbacks();
pspAudioInit();
SceCtrlData pad;
int i;
Now for the shiny new stuff!
scePowerSetClockFrequency(333, 333, 166);
pspDebugScreenInit();
SetupCallbacks();
pspAudioInit();
SceCtrlData pad;
int i;
MP3_Init(1);
MP3_Load("test.mp3");
MP3_Play();
MP3_Init() initialises the structures used by libmad and sets which channel the PSP will be playing back on (in this case, Channel 1). MP3_Load() is pretty self descriptive, it loads your MP3 file
(either change this to your MP3 filename or change your MP3 to be called "test.mp3"). MP3_Play() starts the sound playing through the speakers.MP3_Load("test.mp3");
MP3_Play();
Next up is part three where we'll continue building our program.