From 70085588d68c8445df900a33b50b50e01c6acf32 Mon Sep 17 00:00:00 2001
From: itsmattkc <itsmattkc@gmail.com>
Date: Mon, 10 Aug 2020 17:12:39 +1000
Subject: [PATCH] audiomonitor: fixed bug where audio was shown at normal speed
 even if playing faster

---
 app/widget/audiomonitor/audiomonitor.cpp | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/app/widget/audiomonitor/audiomonitor.cpp b/app/widget/audiomonitor/audiomonitor.cpp
index 86b53a8df..a4cbd853d 100644
--- a/app/widget/audiomonitor/audiomonitor.cpp
+++ b/app/widget/audiomonitor/audiomonitor.cpp
@@ -275,23 +275,33 @@ void AudioMonitor::UpdateValuesFromFile(QVector<double>& v)
   // Determines how many milliseconds have passed since last update
   qint64 current_time = QDateTime::currentMSecsSinceEpoch();
   qint64 time_passed = current_time - last_time_;
+  int abs_speed = qAbs(playback_speed_);
+
+  // Multiply by speed if the speed is not 1
+  if (abs_speed != 1) {
+    time_passed *= abs_speed;
+  }
 
   // Convert ms to float seconds and determine how many bytes that is
   qint64 bytes_to_read = params_.time_to_bytes(static_cast<double>(time_passed) * 0.001);
 
   if (playback_speed_ < 0) {
+    // If reversing, jump back by the amount of bytes we're going to read
     bytes_to_read = qMin(bytes_to_read, file_.pos());
 
     file_.seek(file_.pos() - bytes_to_read);
   }
 
+  // Read bytes in from file
   QByteArray b = file_.read(bytes_to_read);
 
   if (playback_speed_ < 0) {
+    // If reversing, head back to where we were before the read so that the next read starts
+    // from where we left off
     file_.seek(file_.pos() - bytes_to_read);
   }
 
-  int abs_speed = qAbs(playback_speed_);
+  // If speed is not 1, transform it here
   if (abs_speed != 1) {
     int sample_sz = params_.samples_to_bytes(1);
     int in_nb_samples = params_.bytes_to_samples(b.size());
@@ -299,8 +309,8 @@ void AudioMonitor::UpdateValuesFromFile(QVector<double>& v)
     QByteArray speed_adjusted(out_nb_samples * sample_sz, Qt::Uninitialized);
 
     for (int i=0;i<out_nb_samples;i++) {
-      memcpy(speed_adjusted.data() + params_.samples_to_bytes(i),
-             b.constData() + params_.samples_to_bytes(i * abs_speed),
+      memcpy(speed_adjusted.data() + i * sample_sz,
+             b.constData() + i * abs_speed * sample_sz,
              sample_sz);
     }