Bug fixes and comments in audio recording demo

2 files changed, 11 insertions, 6 deletions

diff --git a/demos/modules/gaudio/oscilloscope/gwinosc.c b/demos/modules/gaudio/oscilloscope/gwinosc.c
index 9d095c86..6b51232b 100644
--- a/demos/modules/gaudio/oscilloscope/gwinosc.c
+++ b/demos/modules/gaudio/oscilloscope/gwinosc.c
@@ -144,10 +144,10 @@ void gwinScopeWaitForTrace(GHandle gh) {
 		scopemin = 0;
 	#endif
 
-	for(i = paud->len/(gfxSampleFormatBits(gs->format)/8); i; i--) {
+	for(i = paud->len/((gfxSampleFormatBits(gs->format)+7)/8); i; i--) {
 
 		/* Calculate the new scope value - re-scale using simple shifts for efficiency, re-center and y-invert */
-		if (gs->format <= 8)
+		if (gfxSampleFormatBits(gs->format) <= 8)
 			y = yoffset - (((coord_t)(*pa8++ ) << shr) >> (16-SCOPE_Y_BITS));
 		else
 			y = yoffset - (((coord_t)(*pa16++) << shr) >> (16-SCOPE_Y_BITS));
diff --git a/demos/modules/gaudio/oscilloscope/main.c b/demos/modules/gaudio/oscilloscope/main.c
index a0b9320e..9b53de8e 100644
--- a/demos/modules/gaudio/oscilloscope/main.c
+++ b/demos/modules/gaudio/oscilloscope/main.c
@@ -55,10 +55,15 @@ int main(void) {
 
 	gfxInit();
 
-	// Allocate audio buffers - 4 x 128 byte buffers.
-	//	You may need to increase this for slower cpu's.
-	//	You may be able to decrease this for low latency operating systems.
-	gfxBufferAlloc(4, 128);
+	/**
+	 * Allocate audio buffers - eg. 4 x 128 byte buffers.
+	 *	You may need to increase this for slower cpu's.
+	 *	You may be able to decrease this for low latency operating systems.
+	 *	16 x 256 seems to work on the really slow Olimex SAM7EX256 board (display speed limitation) @8kHz
+	 * If your oscilloscope display stops then it is likely that your driver has stalled due to running
+	 *  out of free buffers. Increase the number of buffers..
+	 */
+	gfxBufferAlloc(16, 256);
 
 	/* Get the screen dimensions */
 	swidth = gdispGetWidth();