Explicit memory management for CMSampleBufferRef

- Explicitly CFRetain/CFRelease CMSampleBufferRef and CVImageBufferRef
  to prevent memory issues
- CVPixelBufferLockBaseAddress and CVPixelBufferUnlockBaseAddress while
  image buffer data is retained
- See issue #194

Author: Bryant Luk

Classes/CardIOIplImage.mm

@@ -13,6 +13,7 @@
 @interface CardIOIplImage ()
 
 @property(nonatomic, assign, readwrite) IplImage *image;
+@property(nonatomic, assign, readwrite) CVImageBufferRef imageBuffer;
 
 @end
 
@@ -26,8 +27,10 @@ + (CardIOIplImage *)imageWithSize:(CvSize)size depth:(int)depth channels:(int)ch
 }
 
 + (CardIOIplImage *)imageFromYCbCrBuffer:(CVImageBufferRef)imageBuffer plane:(size_t)plane {
+  CVPixelBufferLockBaseAddress(imageBuffer, 0);
   char *planeBaseAddress = (char *)CVPixelBufferGetBaseAddressOfPlane(imageBuffer, plane);
-  
+  // CVPixelBufferUnlocked in dealloc of CardIOIplImage to ensure lock of memory
+
   size_t width = CVPixelBufferGetWidthOfPlane(imageBuffer, plane);
   size_t height = CVPixelBufferGetHeightOfPlane(imageBuffer, plane);
   size_t bytesPerRow = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer, plane);
@@ -37,16 +40,25 @@ + (CardIOIplImage *)imageFromYCbCrBuffer:(CVImageBufferRef)imageBuffer plane:(si
   colocatedImage->imageData = planeBaseAddress;
   colocatedImage->widthStep = (int)bytesPerRow;
 
-  return [self imageWithIplImage:colocatedImage];
+  return [[self alloc] initWithIplImage:colocatedImage imageBuffer:imageBuffer];
 }
 
 + (CardIOIplImage *)imageWithIplImage:(IplImage *)anImage {
   return [[self alloc] initWithIplImage:anImage];
 }
 
 - (id)initWithIplImage:(IplImage *)anImage {
+  return [self initWithIplImage:anImage imageBuffer:NULL];
+}
+
+- (id)initWithIplImage:(IplImage *)anImage imageBuffer:(CVImageBufferRef)imageBuffer {
   if((self = [super init])) {
     self.image = anImage;
+
+    self.imageBuffer = imageBuffer;
+    if (imageBuffer != NULL) {
+      CFRetain(imageBuffer);
+    }
   }
   return self;
 }
@@ -78,6 +90,10 @@ - (NSString *)description {
 
 - (void)dealloc {
   cvReleaseImage(&image);
+  if(_imageBuffer != nil) {
+    CVPixelBufferUnlockBaseAddress(_imageBuffer, 0);
+    CFRelease(_imageBuffer);
+  }
 }
 
 - (IplImage *)image {

Classes/CardIOVideoFrame.mm

@@ -52,12 +52,18 @@ @implementation CardIOVideoFrame
 - (id)initWithSampleBuffer:(CMSampleBufferRef)sampleBuffer interfaceOrientation:(UIInterfaceOrientation)currentOrientation {
   if((self = [super init])) {
     _buffer = sampleBuffer;
+    CFRetain(_buffer);
+
     _orientation = currentOrientation; // not using setters/getters, for performance
     _dmz = NULL;  // use NULL b/c non-object pointer
   }
   return self;
 }
 
+- (void)dealloc {
+  CFRelease(_buffer);
+}
+
 #if USE_CAMERA
 
 - (void)process {