From 14051f04cf33aca9feeead5b7ed192f811c30798 Mon Sep 17 00:00:00 2001
From: Paul Licameli <paul.licameli@gmail.com>
Date: Mon, 11 Jun 2018 14:05:00 -0400
Subject: [PATCH] Bug1887: crash or hang loop-playing with WASAPI; libsoxr
 0.1.3 to blame...

... probably?  This is a workaround to prevent crashes in libsoxr that did
not happen with the previous version.
---
 src/Mix.cpp | 29 +++++++++++++++++++++--------
 src/Mix.h   |  3 +++
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/src/Mix.cpp b/src/Mix.cpp
index 4e0b2fd6c..57638e414 100644
--- a/src/Mix.cpp
+++ b/src/Mix.cpp
@@ -313,32 +313,34 @@ Mixer::Mixer(const WaveTrackConstArray &inputTracks,
    // For each queue, the number of available samples after the queue start.
    mQueueLen.reinit(mNumInputTracks);
    mResample.reinit(mNumInputTracks);
-   for(size_t i=0; i<mNumInputTracks; i++) {
+   mMinFactor.resize(mNumInputTracks);
+   mMaxFactor.resize(mNumInputTracks);
+   for (size_t i = 0; i<mNumInputTracks; i++) {
       double factor = (mRate / mInputTrack[i].GetTrack()->GetRate());
-      double minFactor, maxFactor;
       if (mTimeTrack) {
          // variable rate resampling
          mbVariableRates = true;
-         minFactor = factor / mTimeTrack->GetRangeUpper();
-         maxFactor = factor / mTimeTrack->GetRangeLower();
+         mMinFactor[i] = factor / mTimeTrack->GetRangeUpper();
+         mMaxFactor[i] = factor / mTimeTrack->GetRangeLower();
       }
       else if (warpOptions.minSpeed > 0.0 && warpOptions.maxSpeed > 0.0) {
          // variable rate resampling
          mbVariableRates = true;
-         minFactor = factor / warpOptions.maxSpeed;
-         maxFactor = factor / warpOptions.minSpeed;
+         mMinFactor[i] = factor / warpOptions.maxSpeed;
+         mMaxFactor[i] = factor / warpOptions.minSpeed;
       }
       else {
          // constant rate resampling
          mbVariableRates = false;
-         minFactor = maxFactor = factor;
+         mMinFactor[i] = mMaxFactor[i] = factor;
       }
 
-      mResample[i] = std::make_unique<Resample>(mHighQuality, minFactor, maxFactor);
       mQueueStart[i] = 0;
       mQueueLen[i] = 0;
    }
 
+   MakeResamplers();
+
    const auto envLen = std::max(mQueueMaxLen, mInterleavedBufferSize);
    mEnvValues.reinit(envLen);
 }
@@ -347,6 +349,12 @@ Mixer::~Mixer()
 {
 }
 
+void Mixer::MakeResamplers()
+{
+   for (size_t i = 0; i < mNumInputTracks; i++)
+      mResample[i] = std::make_unique<Resample>(mHighQuality, mMinFactor[i], mMaxFactor[i]);
+}
+
 void Mixer::ApplyTrackGains(bool apply)
 {
    mApplyTrackGains = apply;
@@ -709,6 +717,11 @@ void Mixer::Restart()
       mQueueStart[i] = 0;
       mQueueLen[i] = 0;
    }
+
+   // Bug 1887:  libsoxr 0.1.3, first used in Audacity 2.3.0, crashes with
+   // constant rate resampling if you try to reuse the resampler after it has
+   // flushed.  Should that be considered a bug in sox?  This works around it:
+   MakeResamplers();
 }
 
 void Mixer::Reposition(double t)
diff --git a/src/Mix.h b/src/Mix.h
index b5fc823f6..394f45910 100644
--- a/src/Mix.h
+++ b/src/Mix.h
@@ -157,6 +157,8 @@ class AUDACITY_DLL_API Mixer {
                                 int *queueStart, int *queueLen,
                                 Resample * pResample);
 
+   void MakeResamplers();
+
  private:
 
     // Input
@@ -192,6 +194,7 @@ class AUDACITY_DLL_API Mixer {
    double           mRate;
    double           mSpeed;
    bool             mHighQuality;
+   std::vector<double> mMinFactor, mMaxFactor;
 
    bool             mMayThrow;
 };