From ac9152c2796ea8dd9948ec88ea1e2e0962e917e0 Mon Sep 17 00:00:00 2001
From: Stephen Birarda <commit@birarda.com>
Date: Mon, 4 Feb 2013 08:30:11 -0800
Subject: [PATCH] fix a miscalculation in ring buffer wrap around

---
 Source/Audio.cpp           | 7 ++++---
 Source/AudioRingBuffer.cpp | 2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/Source/Audio.cpp b/Source/Audio.cpp
index 74638ad5c5..5d350558cc 100644
--- a/Source/Audio.cpp
+++ b/Source/Audio.cpp
@@ -24,7 +24,7 @@ const short PACKET_LENGTH_SAMPLES = PACKET_LENGTH_BYTES / sizeof(int16_t);
 const int PHASE_DELAY_AT_90 = 20;
 const float AMPLITUDE_RATIO_AT_90 = 0.5;
 
-const short RING_BUFFER_FRAMES = 4;
+const short RING_BUFFER_FRAMES = 5;
 const short RING_BUFFER_SIZE_SAMPLES = RING_BUFFER_FRAMES * BUFFER_LENGTH_SAMPLES;
 
 const short JITTER_BUFFER_LENGTH_MSECS = 3;
@@ -235,6 +235,7 @@ void *receiveAudioViaUDP(void *args) {
                 
                 // check for possibility of overlap
                 bufferSampleOverlap = ringBuffer->bufferOverlap(copyToPointer, PACKET_LENGTH_SAMPLES);
+                
             }
             
             if (!bufferSampleOverlap) {
@@ -254,11 +255,11 @@ void *receiveAudioViaUDP(void *args) {
                     memcpy(copyToPointer, receivedData, PACKET_LENGTH_BYTES);
                     ringBuffer->endOfLastWrite += PACKET_LENGTH_SAMPLES;
                 }
-            } else {
+            } else {                
                 // no jitter buffer, but overlap
                 // copy to the end, and then from the begining to the overlap
                 memcpy(copyToPointer, receivedData, (PACKET_LENGTH_SAMPLES - bufferSampleOverlap) * sizeof(int16_t));
-                memcpy(ringBuffer->buffer, receivedData + bufferSampleOverlap, bufferSampleOverlap * sizeof(int16_t));
+                memcpy(ringBuffer->buffer, receivedData + (PACKET_LENGTH_SAMPLES - bufferSampleOverlap), bufferSampleOverlap * sizeof(int16_t));
                 
                 // the end of the write is the amount of overlap
                 ringBuffer->endOfLastWrite = ringBuffer->buffer + bufferSampleOverlap;
diff --git a/Source/AudioRingBuffer.cpp b/Source/AudioRingBuffer.cpp
index 6cb617457d..215d2c5ad5 100644
--- a/Source/AudioRingBuffer.cpp
+++ b/Source/AudioRingBuffer.cpp
@@ -36,7 +36,7 @@ short AudioRingBuffer::bufferOverlap(int16_t *pointer, short addedDistance)
 {
     short samplesLeft = (buffer + ringBufferLengthSamples) - pointer;
     
-    if (samplesLeft <= addedDistance) {
+    if (samplesLeft < addedDistance) {
         return addedDistance - samplesLeft;
     } else {
         return 0;