Open Radar

 
When setting the 'kCMSampleBufferAttachmentKey_PostNotificationWhenConsumed' attachment on a CMSampleBufferRef and enqueueing the CMSampleBufferRef into a AVSampleBufferDisplayLayer, I expect the 'kCMSampleBufferConsumerNotification_BufferConsumed' notification to be posted when the buffer has been consumed. 

It works as expected when running in the simulator, but the notification is never posted when running on a real device.
    




Code to reproduce issue:

#import "ViewController.h"
@import AVFoundation;
@import UIKit;
@import CoreVideo;

@interface SampleBufferView : UIView
@property (nonatomic, readonly) AVSampleBufferDisplayLayer *sampleBufferDisplayLayer;
@end

@implementation SampleBufferView

+ (Class)layerClass {
    return [AVSampleBufferDisplayLayer class];
}
- (AVSampleBufferDisplayLayer *)sampleBufferDisplayLayer {
    return (AVSampleBufferDisplayLayer *)self.layer;
}
@end

@interface ViewController ()
@property (nonatomic, readonly) SampleBufferView *sampleBufferView;
@end

@implementation ViewController

///This callback is only called when running in simulator - not when running on an actual device.
void cmSampleBufferConsumedNotificationCallback (CFNotificationCenterRef center,
                           void * observer,
                           CFStringRef name,
                           const void * object,
                           CFDictionaryRef userInfo) {
    NSLog(@"Successfully received notification: '%@'", name);
}

- (void)loadView {
    self.view = [SampleBufferView new];
}

-(void)viewDidLoad
{
    [super viewDidLoad];

    //Register observer for the 'kCMSampleBufferConsumerNotification_BufferConsumed' notification
    CFNotificationCenterRef center = CFNotificationCenterGetLocalCenter();
    CFNotificationCenterAddObserver(center, NULL, cmSampleBufferConsumedNotificationCallback,
                                    kCMSampleBufferConsumerNotification_BufferConsumed,
                                    NULL,
                                    CFNotificationSuspensionBehaviorDeliverImmediately);

}

- (SampleBufferView *)sampleBufferView {
    return (SampleBufferView *)self.view;
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
    [self displayTestBuffer];
}

- (void)displayTestBuffer {

    NSDictionary *attributes = @{ (id)kCVPixelBufferIOSurfacePropertiesKey: @{} };

    CVPixelBufferRef pixelBuffer;
    if (CVPixelBufferCreate(kCFAllocatorDefault,
                            1920,
                            1080,
                            kCVPixelFormatType_420YpCbCr8BiPlanarVideoRange,
                            (__bridge CFDictionaryRef)attributes,
                            &pixelBuffer) != kCVReturnSuccess) {
        [NSException raise:NSInternalInconsistencyException
                    format:@"Failure in CVPixelBufferCreate"];
        return;
    }

    CMVideoFormatDescriptionRef formatDescription;
    if (CMVideoFormatDescriptionCreateForImageBuffer(kCFAllocatorDefault,
                                                     pixelBuffer,
                                                     &formatDescription) != noErr) {
        [NSException raise:NSInternalInconsistencyException
                    format:@"Failure in CMVideoFormatDescriptionCreateForImageBuffer"];
        return;
    }

    CMSampleBufferRef sampleBuffer;
    if (CMSampleBufferCreateReadyWithImageBuffer(kCFAllocatorDefault,
                                                 pixelBuffer,
                                                 formatDescription,
                                                 &kCMTimingInfoInvalid,
                                                 &sampleBuffer) != noErr) {
        [NSException raise:NSInternalInconsistencyException
                    format:@"Failure in CMSampleBufferCreateReadyWithImageBuffer"];
        return;
    }

    //Set attachment 'kCMSampleBufferAttachmentKey_PostNotificationWhenConsumed' - will only post a notification when running in simulator, not when running on a real device
    CFDictionaryRef userInfo = CFDictionaryCreate(NULL, NULL, NULL, 0, NULL, NULL);
    CMSetAttachment(sampleBuffer, kCMSampleBufferAttachmentKey_PostNotificationWhenConsumed,
                    userInfo, kCMAttachmentMode_ShouldPropagate);
    CFRelease(userInfo);


    //Set attachment 'kCMSampleAttachmentKey_DisplayImmediately'
    CFArrayRef attachmentsArray = CMSampleBufferGetSampleAttachmentsArray(sampleBuffer, true);
    CFMutableDictionaryRef attachments = (CFMutableDictionaryRef)CFArrayGetValueAtIndex(attachmentsArray, 0);
    CFDictionarySetValue(attachments, kCMSampleAttachmentKey_DisplayImmediately, kCFBooleanTrue);

    [self.sampleBufferView.sampleBufferDisplayLayer enqueueSampleBuffer:sampleBuffer];

    CVPixelBufferRelease(pixelBuffer);
    CFRelease(formatDescription);
    CFRelease(sampleBuffer);
}

@end