Seamless audio looping

Audio channel selection fix
Audio debugging


git-svn-id: svn://cook.msm.cam.ac.uk:745/thrust3d/thrust3d@112 84d2e878-0bd5-11dd-ad15-13eda11d74c5

1 files changed, 22 insertions, 21 deletions

diff --git a/src/audio.c b/src/audio.c
index 8bb95fa..c3a0492 100644
--- a/src/audio.c
+++ b/src/audio.c
@@ -22,7 +22,6 @@ static void audio_mix(void *data, Uint8 *stream8, int len) {
 
 	AudioContext *a = data;
 	int i, j;
-	Uint32 amount;
 	Sint16 *stream = (Sint16 *)stream8;
 	
 	len /= 2;	/* Samples */
@@ -38,27 +37,25 @@ static void audio_mix(void *data, Uint8 *stream8, int len) {
 		/* Playing? */
 		if ( !a->sounds[i].inuse ) continue;
 		
-		/* Calculate how many samples to mix */
-		amount = a->sounds[i].dlen - a->sounds[i].dpos;
+		for ( j=0; j<len; j++ ) {
 		
-		if ( amount > len ) {
-			/* The sound remaining in this channel more than fills the buffer */
-			amount = len;
-		}
-		
-		for ( j=0; j<amount; j++ ) {
-			Sint16 samp = a->sounds[i].data[a->sounds[i].dpos + j];
+			Sint16 samp;
+			
+			samp = a->sounds[i].data[a->sounds[i].dpos++];
 			stream[j] += samp * a->sounds[i].volume;
-		}
-		
-		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);
+			
+			if ( a->sounds[i].dpos == a->sounds[i].dlen ) {
+				if ( a->sounds[i].repeat ) {
+					a->sounds[i].dpos = 0;
+					if ( a->debug ) printf("AU: Looping sound %i at buffer offset %i/%i\n", i, j, len);
+				} else {
+					a->sounds[i].inuse = 0;
+					free(a->sounds[i].data);
+					if ( a->debug ) printf("AU: End of sound %i\n", i);
+					break;
+				}
 			}
+		
 		}
 		
 	}
@@ -74,10 +71,11 @@ void audio_play(AudioContext *a, char *file, float volume, int repeat) {
 	SDL_AudioCVT cvt;
 	char filename[128];
 	
-	/* Look for an empty (or finished) sound slot */
+	/* Look for an empty sound slot */
 	for ( idx=0; idx<AUDIO_MAX_SOUNDS; idx++ ) {
-		if ( a->sounds[idx].dpos == a->sounds[idx].dlen ) break;
+		if ( !a->sounds[idx].inuse ) break;
 	}
+	if ( a->debug ) printf("AU: Selected channel %i for sound '%s'\n", idx, file);
 	if ( idx == AUDIO_MAX_SOUNDS ) {
 		fprintf(stderr, "Not enough audio channels to play '%s'\n", file);
 		return;
@@ -116,9 +114,12 @@ AudioContext *audio_setup() {
 	SDL_AudioSpec fmt;
 	int i;
 	
+	/* Create audio context */
 	a = malloc(sizeof(AudioContext));
 	if ( a == NULL ) return NULL;
 	
+	/* Initialise audio context */
+	a->debug = 0;
 	for ( i=0; i<AUDIO_MAX_SOUNDS; i++ ) {
 		a->sounds[i].inuse = 0;
 	}