ios9 - Issues with cropping CVImageBuffer - ios

Question

I am facing few issues related to cropping with iOS9 SDK.
I have the following code to resize a image (converting from 4:3 to 16:9 by cropping in middle). This used to work fine till iOS8 SDK. With iOS 9, the bottom area is blank.
(CMSampleBufferRef)resizeImage:(CMSampleBufferRef) sampleBuffer {
{
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(imageBuffer,0);
int target_width = CVPixelBufferGetWidth(imageBuffer);
int target_height = CVPixelBufferGetHeight(imageBuffer);
int height = CVPixelBufferGetHeight(imageBuffer);
int width = CVPixelBufferGetWidth(imageBuffer);
int x=0, y=0;
// Convert 16:9 to 4:3
if (((target_width*3)/target_height) == 4)
{
target_height = ((target_width*9)/16);
target_height = ((target_height + 15) / 16) * 16;
y = (height - target_height)/2;
}
else
if ((target_width == 352) && (target_height == 288))
{
target_height = ((target_width*9)/16);
target_height = ((target_height + 15) / 16) * 16;
y = (height - target_height)/2;
}
else
if (((target_height*3)/target_width) == 4)
{
target_width = ((target_height*9)/16);
target_width = ((target_width + 15) / 16) * 16;
x = ((width - target_width)/2);
}
else
if ((target_width == 288) && (target_height == 352))
{
target_width = ((target_height*9)/16);
target_width = ((target_width + 15) / 16) * 16;
x = ((width - target_width)/2);
}
CGRect cropRect;
NSLog(#"resizeImage x %d, y %d, target_width %d, target_height %d", x, y, target_width, target_height );
cropRect = CGRectMake(x, y, target_width, target_height);
CFDictionaryRef empty; // empty value for attr value.
CFMutableDictionaryRef attrs;
empty = CFDictionaryCreate(kCFAllocatorDefault, // our empty IOSurface properties dictionary
NULL,
NULL,
0,
&kCFTypeDictionaryKeyCallBacks,
&kCFTypeDictionaryValueCallBacks);
attrs = CFDictionaryCreateMutable(kCFAllocatorDefault,
1,
&kCFTypeDictionaryKeyCallBacks,
&kCFTypeDictionaryValueCallBacks);
CFDictionarySetValue(attrs,
kCVPixelBufferIOSurfacePropertiesKey,
empty);
OSStatus status;
CIImage *ciImage = [CIImage imageWithCVPixelBuffer:imageBuffer]; //options: [NSDictionary dictionaryWithObjectsAndKeys:[NSNull null], kCIImageColorSpace, nil]];
CVPixelBufferRef pixelBuffer;
status = CVPixelBufferCreate(kCFAllocatorSystemDefault, target_width, target_height, kCVPixelFormatType_420YpCbCr8BiPlanarFullRange, attrs, &pixelBuffer);
if (status != 0)
{
NSLog(#"CVPixelBufferCreate error %d", (int)status);
}
[ciContext render:ciImage toCVPixelBuffer:pixelBuffer bounds:cropRect colorSpace:nil];
CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 );
CVPixelBufferUnlockBaseAddress( imageBuffer,0);
CMSampleTimingInfo sampleTime = {
.duration = CMSampleBufferGetDuration(sampleBuffer),
.presentationTimeStamp = CMSampleBufferGetPresentationTimeStamp(sampleBuffer),
.decodeTimeStamp = CMSampleBufferGetDecodeTimeStamp(sampleBuffer)
};
CMVideoFormatDescriptionRef videoInfo = NULL;
status = CMVideoFormatDescriptionCreateForImageBuffer(kCFAllocatorDefault, pixelBuffer, &videoInfo);
if (status != 0)
{
NSLog(#"CMVideoFormatDescriptionCreateForImageBuffer error %d", (int)status);
}
CMSampleBufferRef oBuf;
status = CMSampleBufferCreateForImageBuffer(kCFAllocatorDefault, pixelBuffer, true, NULL, NULL, videoInfo, &sampleTime, &oBuf);
if (status != 0)
{
NSLog(#"CMSampleBufferCreateForImageBuffer error %d", (int)status);
}
CFRelease(pixelBuffer);
ciImage = nil;
pixelBuffer = nil;
return oBuf;
}
}
Any ideas or suggestions regarding this? I tried changing the crop rectangle but with no effect.
Thanks

Answer 1

Are you aware that the doc comment of the function [CIContext toCVPixelBuffer: bounds: colorSpace:] says about iOS8- and iOS9+? (I could've not found any online resource to link, though.)
/* Render 'image' to the given CVPixelBufferRef.
* The 'bounds' parameter has the following behavior:
* In OS X and iOS 9 and later: The 'image' is rendered into 'buffer' so that
* point (0,0) of 'image' aligns to the lower left corner of 'buffer'.
* The 'bounds' acts like a clip rect to limit what region of 'buffer' is modified.
* In iOS 8 and earlier: The 'bounds' parameter acts to specify the region of 'image' to render.
* This region (regarless of its origin) is rendered at upper-left corner of 'buffer'.
*/
Taking it into account I solved my problem, which looks the same as yours.