From 2599c1e8a41ea07f9d2cb3f4632df6dcbb7245be Mon Sep 17 00:00:00 2001
From: itsmattkc <itsmattkc@gmail.com>
Date: Wed, 20 Nov 2019 10:32:46 +0900
Subject: [PATCH] forego memory sample buffer and only write samples that need
 writing

Rather than writing the entire sequence audio to disk every change, now we
just write the parts we need to write.
---
 app/render/backend/audio/audiobackend.cpp | 49 +++++++++++++++--------
 app/render/backend/audio/audiobackend.h   |  3 ++
 app/render/backend/audiorenderbackend.cpp |  6 ---
 app/render/backend/audiorenderbackend.h   |  2 -
 4 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/app/render/backend/audio/audiobackend.cpp b/app/render/backend/audio/audiobackend.cpp
index 0521d75a5..e50328d4a 100644
--- a/app/render/backend/audio/audiobackend.cpp
+++ b/app/render/backend/audio/audiobackend.cpp
@@ -19,6 +19,19 @@ QIODevice *AudioBackend::GetAudioPullDevice()
   return &pull_device_;
 }
 
+void AudioBackend::InvalidateCache(const rational &start_range, const rational &end_range)
+{
+  /*
+  // Truncate to length if necessary
+  int max_length_in_bytes = params().time_to_bytes(viewer_node()->Length());
+  if (pcm_data_.size() > max_length_in_bytes) {
+    pcm_data_.resize(max_length_in_bytes);
+  }
+  */
+
+  AudioRenderBackend::InvalidateCache(start_range, end_range);
+}
+
 bool AudioBackend::InitInternal()
 {
   // Initiate one thread per CPU core
@@ -34,7 +47,6 @@ bool AudioBackend::InitInternal()
 
 void AudioBackend::CloseInternal()
 {
-  // This backend doesn't init anything yet
 }
 
 bool AudioBackend::CompileInternal()
@@ -63,23 +75,26 @@ void AudioBackend::ThreadCompletedCache(NodeDependency dep)
   int length = params().time_to_bytes(dep.range().length());
   int out_point = offset + length;
 
-  if (pcm_data_.size() < out_point) {
-    pcm_data_.resize(out_point);
-  }
-
-  // Replace data with this data
-  int copy_length = qMin(length, cached_samples.size());
-
-  memcpy(pcm_data_.data() + offset, cached_samples.data(), static_cast<size_t>(copy_length));
-
-  if (copy_length < length) {
-    // Fill in remainder with silence
-    memset(pcm_data_.data() + offset + copy_length, 0, static_cast<size_t>(length - copy_length));
-  }
-
   QFile f(CachePathName());
-  if (f.open(QFile::WriteOnly)) {
-    f.write(pcm_data_);
+  if (f.open(QFile::WriteOnly | QFile::Append)) {
+
+    if (f.size() < out_point) {
+      f.resize(out_point);
+    }
+
+    f.seek(offset);
+
+    // Replace data with this data
+    int copy_length = qMin(length, cached_samples.size());
+
+    f.write(cached_samples.data(), copy_length);
+
+    if (copy_length < length) {
+      // Fill in remainder with silence
+      QByteArray empty_space(length - copy_length, 0);
+      f.write(empty_space);
+    }
+
     f.close();
   }
 
diff --git a/app/render/backend/audio/audiobackend.h b/app/render/backend/audio/audiobackend.h
index 7cbe4c428..3fca71a12 100644
--- a/app/render/backend/audio/audiobackend.h
+++ b/app/render/backend/audio/audiobackend.h
@@ -15,6 +15,9 @@ public:
 
   virtual QIODevice* GetAudioPullDevice() override;
 
+public slots:
+  virtual void InvalidateCache(const rational &start_range, const rational &end_range) override;
+
 protected:
   virtual bool InitInternal() override;
 
diff --git a/app/render/backend/audiorenderbackend.cpp b/app/render/backend/audiorenderbackend.cpp
index 044ae8000..c72424db3 100644
--- a/app/render/backend/audiorenderbackend.cpp
+++ b/app/render/backend/audiorenderbackend.cpp
@@ -28,12 +28,6 @@ void AudioRenderBackend::InvalidateCache(const rational &start_range, const rati
   rational start_range_adj = qMax(rational(0), start_range);
   rational end_range_adj = qMin(viewer_node()->Length(), end_range);
 
-  // Truncate to length if necessary
-  int max_length_in_bytes = params().time_to_bytes(viewer_node()->Length());
-  if (pcm_data_.size() > max_length_in_bytes) {
-    pcm_data_.resize(max_length_in_bytes);
-  }
-
   // Add the range to the list
   cache_queue_.append(TimeRange(start_range_adj, end_range_adj));
 
diff --git a/app/render/backend/audiorenderbackend.h b/app/render/backend/audiorenderbackend.h
index 2270921f0..1685a6b4f 100644
--- a/app/render/backend/audiorenderbackend.h
+++ b/app/render/backend/audiorenderbackend.h
@@ -39,8 +39,6 @@ protected:
 
   QString CachePathName();
 
-  QByteArray pcm_data_;
-
 private:
   void ValidateRanges();