From 4fc278eb4639486ba6520c3b66f8c385dea82985 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Mon, 12 May 2025 17:23:25 -0500
Subject: [PATCH] fix audio problems in SDL audio backend

this was a Furnace bug
issue #2503
---
 src/audio/sdlAudio.cpp | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/audio/sdlAudio.cpp b/src/audio/sdlAudio.cpp
index feb99657c..bcf7f9212 100644
--- a/src/audio/sdlAudio.cpp
+++ b/src/audio/sdlAudio.cpp
@@ -27,16 +27,36 @@ void taSDLProcess(void* inst, unsigned char* buf, int nframes) {
 }
 
 void TAAudioSDL::onProcess(unsigned char* buf, int nframes) {
+  unsigned int unframes=nframes/(sizeof(float)*desc.outChans);
+  if (nframes<0) {
+    logE("nframes is negative! (%d)",nframes);
+    return;
+  }
+  for (int i=0; i<desc.inChans; i++) {
+    if (unframes>desc.bufsize) {
+      delete[] inBufs[i];
+      inBufs[i]=new float[unframes];
+    }
+  }
+  for (int i=0; i<desc.outChans; i++) {
+    if (unframes>desc.bufsize) {
+      delete[] outBufs[i];
+      outBufs[i]=new float[unframes];
+    }
+  }
   if (audioProcCallback!=NULL) {
     if (midiIn!=NULL) midiIn->gather();
-    audioProcCallback(audioProcCallbackUser,inBufs,outBufs,desc.inChans,desc.outChans,desc.bufsize);
+    audioProcCallback(audioProcCallbackUser,inBufs,outBufs,desc.inChans,desc.outChans,unframes);
   }
   float* fbuf=(float*)buf;
-  for (size_t j=0; j<desc.bufsize; j++) {
+  for (size_t j=0; j<unframes; j++) {
     for (size_t i=0; i<desc.outChans; i++) {
       fbuf[j*desc.outChans+i]=outBufs[i][j];
     }
   }
+  if (unframes!=desc.bufsize) {
+    desc.bufsize=unframes;
+  }
 }
 
 void* TAAudioSDL::getContext() {