EXC_BAD_ACCESS KERN_INVALID_ADDRESS crash in AVFoundation when stopping recording

Question

I am getting a randomly occurring crash relating to the finishWritingWithCompletionHandler: method of AVAssetWriter.

This references roCleanupSampleBufferOperation and a

EXC_BAD_ACCESS KERN_INVALID_ADDRESS.

It occur very occasionally and is difficult to reproduce.

Here is the stack trace:

#12. Crashed: com.apple.avfoundation.videodataoutput.bufferqueue
0  libobjc.A.dylib                0x189db57f4 objc_object::release() + 8
1  CoreMedia                      0x18dc5746c roCleanupSampleBufferOperation + 44
2  CoreMedia                      0x18dc55f98 __FigRemoteOperationReceiverCreateMessageReceiver_block_invoke + 308
3  CoreMedia                      0x18dc74e9c __FigRemoteQueueReceiverSetHandler_block_invoke.2 + 224
4  libdispatch.dylib              0x18a1ee9a0 _dispatch_client_callout + 16
5  libdispatch.dylib              0x18a1fb604 _dispatch_continuation_pop + 448
6  libdispatch.dylib              0x18a207c1c _dispatch_source_latch_and_call + 204
7  libdispatch.dylib              0x18a1f08a0 _dispatch_source_invoke + 804
8  libdispatch.dylib              0x18a1fc964 _dispatch_queue_serial_drain + 560
9  libdispatch.dylib              0x18a1f22cc _dispatch_queue_invoke + 884
10 libdispatch.dylib              0x18a1fc964 _dispatch_queue_serial_drain + 560
11 libdispatch.dylib              0x18a1f22cc _dispatch_queue_invoke + 884
12 libdispatch.dylib              0x18a1fd950 _dispatch_root_queue_drain_deferred_item + 256
13 libdispatch.dylib              0x18a204170 _dispatch_kevent_worker_thread + 760
14 libsystem_pthread.dylib        0x18a3f6fbc _pthread_wqthread + 772
15 libsystem_pthread.dylib        0x18a3f6cac start_wqthread + 4

#13. com.apple.root.user-interactive-qos
0  AppleJPEG                      0x18cf856e8 aj_RGBA8888_YUV420 + 528
1  AppleJPEG                      0x18cfa40e4 aj_col_trans_row + 172
2  AppleJPEG                      0x18cf7be5c aj_encode_row + 136
3  AppleJPEG                      0x18cfaca98 applejpeg_encode_image_row + 472
4  ImageIO                        0x18d159c88 AppleJPEGWritePlugin::writeOne(IIOImagePixelDataProvider*, __CFDictionary const*) + 1708
5  ImageIO                        0x18d159f50 AppleJPEGWritePlugin::writeAll() + 448
6  ImageIO                        0x18d15a17c AppleJPEGWritePlugin::WriteProc(void*, __CFDictionary const*, __CFArray const*, __CFArray const*) + 84
7  ImageIO                        0x18d0f1648 IIOImageDestination::finalize() + 556
8  ImageIO                        0x18d0f28d0 CGImageDestinationFinalize + 76
9  UIKit                          0x19172971c _UIImageJPEGRepresentation + 652
10 projectApp                0x100294e0c -[AVCamCaptureManager(InternalUtilityMethods) createThumbFromPath:] + 4296969740
11 projectApp                0x1002957ac -[AVCamCaptureManager(RecorderDelegate) recorder:recordingDidFinishToOutputFileURL:error:] + 4296972204
12 projectApp                0x100299008 __30-[AVCamRecorder stopRecording]_block_invoke + 4296986632
13 Foundation                     0x18be0466c __103+[__NSOperationInternal _observeValueForKeyPath:ofObject:changeKind:oldValue:newValue:indexes:context:]_block_invoke.119 + 28
14 libdispatch.dylib              0x18a1ee9e0 _dispatch_call_block_and_release + 24
15 libdispatch.dylib              0x18a1ee9a0 _dispatch_client_callout + 16
16 libdispatch.dylib              0x18a1febac _dispatch_root_queue_drain + 888
17 libdispatch.dylib              0x18a1fe7d0 _dispatch_worker_thread3 + 124
18 libsystem_pthread.dylib        0x18a3f7100 _pthread_wqthread + 1096
19 libsystem_pthread.dylib        0x18a3f6cac start_wqthread + 4

And here is the code that is run when recording is completed:

[self.assetWriterVideoInput markAsFinished];
        [self.assetWriter finishWritingWithCompletionHandler:^(void){
                if ([[self delegate] respondsToSelector:@selector(recorder:recordingDidFinishToOutputFileURL:error:)]) {
                    NSError* error = nil;
                    [[self delegate] recorder:self recordingDidFinishToOutputFileURL:self.outputFileURL error:error];
                }
            }];

Any help much appreciated

(Update) Here is the delegate method:

-(void)recorder:(AVCamRecorder *)recorder recordingDidFinishToOutputFileURL:(NSURL *)outputFileURL error:(NSError *)error {
    if (error) {
        NSLog(@"recordingDidFinishToOutputFileURL received error: %@",error);   

        if ([[self delegate] respondsToSelector:@selector(captureManagerRecordingFinished:recordedVideo:)]) {
            [[self delegate] captureManagerRecordingFinished:self recordedVideo:nil];
        }
        return;
    }

    [self createThumbFromPath:[ProjectSingleton getVideoPath:outputFileURL]];       

    if ([[self delegate] respondsToSelector:@selector(captureManagerRecordingFinished:recordedVideo:)]) {
        [[self delegate] captureManagerRecordingFinished:self recordedVideo:[outputFileURL path]];
    }
}