Basic audio framework

git-svn-id: svn://cook.msm.cam.ac.uk:745/thrust3d/thrust3d@105 84d2e878-0bd5-11dd-ad15-13eda11d74c5

1 files changed, 123 insertions, 5 deletions

diff --git a/src/audio.c b/src/audio.c
index 1e807b5..d772f6a 100644
--- a/src/audio.c
+++ b/src/audio.c
@@ -13,22 +13,140 @@
 #include <config.h>
 #endif
 
+#include <SDL.h>
+#include <SDL_audio.h>
+
 #include "types.h"
 
-/* OpenGL initial setup */
+void audio_mix(void *data, Uint8 *stream, int len) {
+
+	AudioContext *a = data;
+	int i;
+	Uint32 amount;
+	size_t j;
+	
+	for ( j=0; j<len; j++ ) {
+		stream[j] = 0;
+	}
+	
+	for ( i=0; i<AUDIO_MAX_SOUNDS; i++ ) {
+		
+		if ( !a->sounds[i].inuse ) continue;
+		
+		amount = (a->sounds[i].dlen - a->sounds[i].dpos);
+		if ( amount > len ) {
+			/* The sound remaining in this channel more than fills the buffer */
+			amount = len;
+		}
+		
+		for ( j=0; j<amount; j++ ) {
+			stream[j] += a->sounds[i].data[a->sounds[i].dpos + j];
+		}
+		
+		a->sounds[i].dpos += amount;
+		if ( a->sounds[i].dpos == a->sounds[i].dlen ) {
+			if ( a->sounds[i].repeat ) {
+				a->sounds[i].dpos = 0;
+			} else {
+				a->sounds[i].inuse = 0;
+				free(a->sounds[i].data);
+			}
+		}
+		
+	}
+	
+}
+
+void audio_play(AudioContext *a, char *file, float volume) {
+
+	int idx, i;
+	SDL_AudioSpec wave;
+	Uint8 *data;
+	Uint32 dlen;
+	SDL_AudioCVT cvt;
+	char filename[128];
+	
+	/* Look for an empty (or finished) sound slot */
+	for ( idx=0; idx<AUDIO_MAX_SOUNDS; idx++ ) {
+		if ( a->sounds[idx].dpos == a->sounds[idx].dlen ) break;
+	}
+	if ( idx == AUDIO_MAX_SOUNDS ) {
+		fprintf(stderr, "Not enough audio channels to play '%s'\n", file);
+		return;
+	}
+	
+	snprintf(filename, 127, "%s%s.wav", DATADIR"/sound/", file);
+	
+	/* Load the sound file and convert it to 16-bit stereo at 22kHz */
+	if ( SDL_LoadWAV(filename, &wave, &data, &dlen) == NULL ) {
+		fprintf(stderr, "Couldn't load %s: %s\n", file, SDL_GetError());
+		return;
+	}
+	SDL_BuildAudioCVT(&cvt, wave.format, wave.channels, wave.freq, AUDIO_S16, 2, 22050);
+	cvt.buf = malloc(dlen*cvt.len_mult);
+	memcpy(cvt.buf, data, dlen);
+	cvt.len = dlen;
+	SDL_ConvertAudio(&cvt);
+	SDL_FreeWAV(data);
+	
+	/* Perform volume adjustment here */
+	int16_t *aud = (int16_t *)cvt.buf;
+	for ( i=0; i<dlen/2; i++ ) {
+		float samp = aud[i];
+		samp *= volume;
+		aud[i] = samp;
+	}
+	
+	/* Put the sound data in the slot */
+	SDL_LockAudio();
+	a->sounds[idx].data = cvt.buf;
+	a->sounds[idx].dlen = cvt.len_cvt;
+	a->sounds[idx].dpos = 0;
+	a->sounds[idx].inuse = 1;
+	a->sounds[idx].repeat = 1;
+	SDL_UnlockAudio();
+	
+}
+
+/* SDL audio initial setup */
 AudioContext *audio_setup() {
 	
-	AudioContext *ctx;
+	AudioContext *a;
+	SDL_AudioSpec fmt;
+	int i;
+	
+	a = malloc(sizeof(AudioContext));
+	if ( a == NULL ) return NULL;
+	
+	for ( i=0; i<AUDIO_MAX_SOUNDS; i++ ) {
+		a->sounds[i].inuse = 0;
+	}
+	
+	/* Set 16-bit stereo audio at 22Khz */
+	fmt.freq = 22050;
+	fmt.format = AUDIO_S16;
+	fmt.channels = 2;
+	fmt.samples = 512;
+	fmt.callback = audio_mix;
+	fmt.userdata = a;
+	fmt.silence = 0;
 	
-	ctx = malloc(sizeof(AudioContext));
-	if ( ctx == NULL ) return NULL;
+	/* Open the audio device and start playing sound! */
+	if ( SDL_OpenAudio(&fmt, NULL) < 0 ) {
+		fprintf(stderr, "Unable to open audio: %s\n", SDL_GetError());
+		free(a);
+		return NULL;
+	}
+	SDL_PauseAudio(0);
 	
+	audio_play(a, "moan", 0.4);
 	
-	return ctx;
+	return a;
 	
 }
 
 void audio_shutdown(AudioContext *ctx) {
+	SDL_CloseAudio();
 	free(ctx);
 }