From e47245bd8c210c78af05ebc2aa25df97a7fb4781 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@audacityteam.org>
Date: Fri, 15 Jan 2021 13:19:58 -0500
Subject: [PATCH] Fix use of uninitialized data for meter when emulating volume

---
 src/AudioIO.cpp | 13 ++++++-------
 src/AudioIO.h   |  4 +---
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/src/AudioIO.cpp b/src/AudioIO.cpp
index 8c3783942..93dfd7d38 100644
--- a/src/AudioIO.cpp
+++ b/src/AudioIO.cpp
@@ -3786,7 +3786,6 @@ void AudioIoCallback::CheckSoundActivatedRecordingLevel(
 void AudioIoCallback::AddToOutputChannel( unsigned int chan,
    float * outputMeterFloats,
    float * outputFloats,
-   float * tempFloats,
    float * tempBuf,
    bool drop,
    unsigned long len,
@@ -3804,7 +3803,7 @@ void AudioIoCallback::AddToOutputChannel( unsigned int chan,
    if (outputMeterFloats != outputFloats)
       for ( unsigned i = 0; i < len; ++i)
          outputMeterFloats[numPlaybackChannels*i+chan] +=
-            gain*tempFloats[i];
+            gain*tempBuf[i];
 
    if (mEmulateMixerOutputVol)
       gain *= mMixerOutputVol;
@@ -3836,8 +3835,7 @@ void ClampBuffer(float * pBuffer, unsigned long len){
 //
 bool AudioIoCallback::FillOutputBuffers(
    void *outputBuffer,
-   unsigned long framesPerBuffer,
-   float * tempFloats, float *outputMeterFloats
+   unsigned long framesPerBuffer, float *outputMeterFloats
 )
 {
    const auto numPlaybackTracks = mPlaybackTracks.size();
@@ -3999,11 +3997,13 @@ bool AudioIoCallback::FillOutputBuffers(
 
          if (vt->GetChannelIgnoringPan() == Track::LeftChannel ||
                vt->GetChannelIgnoringPan() == Track::MonoChannel )
-            AddToOutputChannel( 0, outputMeterFloats, outputFloats, tempFloats, tempBufs[c], drop, len, vt);
+            AddToOutputChannel( 0, outputMeterFloats, outputFloats,
+               tempBufs[c], drop, len, vt);
 
          if (vt->GetChannelIgnoringPan() == Track::RightChannel ||
                vt->GetChannelIgnoringPan() == Track::MonoChannel  )
-            AddToOutputChannel( 1, outputMeterFloats, outputFloats, tempFloats, tempBufs[c], drop, len, vt);
+            AddToOutputChannel( 1, outputMeterFloats, outputFloats,
+               tempBufs[c], drop, len, vt);
       }
 
       chanCnt = 0;
@@ -4472,7 +4472,6 @@ int AudioIoCallback::AudioCallback(const void *inputBuffer, void *outputBuffer,
    if( FillOutputBuffers(
          outputBuffer,
          framesPerBuffer,
-         tempFloats,
          outputMeterFloats))
       return mCallbackReturn;
 
diff --git a/src/AudioIO.h b/src/AudioIO.h
index e100b7241..b2aed6931 100644
--- a/src/AudioIO.h
+++ b/src/AudioIO.h
@@ -315,7 +315,6 @@ public:
    void AddToOutputChannel( unsigned int chan,
       float * outputMeterFloats,
       float * outputFloats,
-      float * tempFloats,
       float * tempBuf,
       bool drop,
       unsigned long len,
@@ -323,8 +322,7 @@ public:
       );
    bool FillOutputBuffers(
       void *outputBuffer,
-      unsigned long framesPerBuffer,
-      float * tempFloats, float *outputMeterFloats
+      unsigned long framesPerBuffer, float *outputMeterFloats
    );
    void FillInputBuffers(
       const void *inputBuffer,