use lossless compression on indexed frames

We use Qt's built in zlib compression on the fastest setting (it was found that
higher compression took 5x as long with a negligible decrease in size). This
helps keep disk cache sizes low.

app/codec/ffmpeg/ffmpegdecoder.cpp

@@ -232,7 +232,8 @@ FramePtr FFmpegDecoder::RetrieveVideo(const rational &timecode)
       DiskManager::instance()->Accessed(compressed_frame.fileName());
 
       // Read data
-      frame_loader = compressed_frame.readAll();
+      frame_loader = qUncompress(compressed_frame.readAll());
+      //frame_loader = compressed_frame.readAll();
 
       av_image_fill_arrays(input_data,
                            input_linesize,
@@ -283,9 +284,10 @@ FramePtr FFmpegDecoder::RetrieveVideo(const rational &timecode)
           input_linesize[i] = frame_->linesize[i];
         }
 
-        // Save frame to media index
         QFile save_frame(GetIndexFilename().append(QString::number(frame_->pts)));
         if (save_frame.open(QFile::WriteOnly)) {
+
+          // Save frame to media index
           int cached_buffer_sz = av_image_get_buffer_size(static_cast<AVPixelFormat>(frame_->format),
                                                           frame_->width,
                                                           frame_->height,
@@ -302,13 +304,11 @@ FramePtr FFmpegDecoder::RetrieveVideo(const rational &timecode)
                                   frame_->height,
                                   1);
 
-          // FIXME: No compression
-          save_frame.write(cached_frame);
+          save_frame.write(qCompress(cached_frame, 1));
           save_frame.close();
 
           DiskManager::instance()->CreatedFile(save_frame.fileName(), QByteArray());
         }
-
         break;
       }
     }

app/render/diskmanager.cpp

@@ -78,6 +78,8 @@ DiskManager *DiskManager::instance()
 
 void DiskManager::Accessed(const QByteArray &hash)
 {
+  lock_.lock();
+
   for (int i=disk_data_.size()-1;i>=0;i--) {
     const HashTime& h = disk_data_.at(i);
 
@@ -91,10 +93,14 @@ void DiskManager::Accessed(const QByteArray &hash)
       break;
     }
   }
+
+  lock_.unlock();
 }
 
 void DiskManager::Accessed(const QString &filename)
 {
+  lock_.lock();
+
   for (int i=disk_data_.size()-1;i>=0;i--) {
     const HashTime& h = disk_data_.at(i);
 
@@ -108,29 +114,47 @@ void DiskManager::Accessed(const QString &filename)
       break;
     }
   }
+
+  lock_.unlock();
 }
 
 void DiskManager::CreatedFile(const QString &file_name, const QByteArray &hash)
 {
+  lock_.lock();
+
   qint64 file_size = QFile(file_name).size();
 
   disk_data_.append({file_name, hash, QDateTime::currentMSecsSinceEpoch(), file_size});
 
   consumption_ += file_size;
 
+  QList<QByteArray> deleted_hashes;
+
   while (consumption_ > DiskLimit()) {
-    DeleteLeastRecent();
+    deleted_hashes.append(DeleteLeastRecent());
+  }
+
+  lock_.unlock();
+
+  foreach (const QByteArray& hash, deleted_hashes) {
+    emit DeletedFrame(hash);
   }
 }
 
 bool DiskManager::ClearDiskCache()
 {
+  lock_.lock();
+
+  bool deleted_files = QDir(GetMediaCacheLocation()).removeRecursively();
+
   disk_data_.clear();
 
-  return QDir(GetMediaCacheLocation()).removeRecursively();
+  lock_.unlock();
+
+  return deleted_files;
 }
 
-void DiskManager::DeleteLeastRecent()
+QByteArray DiskManager::DeleteLeastRecent()
 {
   HashTime h = disk_data_.takeFirst();
 
@@ -138,7 +162,7 @@ void DiskManager::DeleteLeastRecent()
 
   consumption_ -= h.file_size;
 
-  emit DeletedFrame(h.hash);
+  return h.hash;
 }
 
 qint64 DiskManager::DiskLimit()

app/render/diskmanager.h

@@ -1,6 +1,7 @@
 #ifndef DISKMANAGER_H
 #define DISKMANAGER_H
 
+#include <QMutex>
 #include <QObject>
 
 class DiskManager : public QObject
@@ -31,7 +32,7 @@ private:
 
   static DiskManager* instance_;
 
-  void DeleteLeastRecent();
+  QByteArray DeleteLeastRecent();
 
   qint64 DiskLimit();
 
@@ -46,6 +47,8 @@ private:
 
   qint64 consumption_;
 
+  QMutex lock_;
+
 };
 
 #endif // DISKMANAGER_H