fragment.m

#import "AppDelegate.h"
#import <AVFoundation/AVFoundation.h>

@interface AppDelegate ()

@property (nonatomic) AVAssetWriter *writer;
@property (nonatomic) AVAssetWriterInputPixelBufferAdaptor *adaptor;
@property (nonatomic) dispatch_queue_t	q;

@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
	NSString *path = @"/Users/gchilds/Desktop/foo.mov";
	NSURL *fileUrl = [NSURL fileURLWithPath:path];
	[[NSFileManager defaultManager] removeItemAtURL:fileUrl error:nil];
	
	NSError *error;
	AVAssetWriter *writer = [[AVAssetWriter alloc] initWithURL:fileUrl fileType:AVFileTypeQuickTimeMovie error:&error];

	NSDictionary*	vidOpts = [NSDictionary dictionaryWithObjectsAndKeys:
							   AVVideoCodecH264, AVVideoCodecKey,	// the only supported codec. perfectly natural.
							   [NSNumber numberWithInt:640], AVVideoWidthKey,
							   [NSNumber numberWithInt:480], AVVideoHeightKey,
							   nil];
	AVAssetWriterInput *writerInput = [[AVAssetWriterInput alloc] initWithMediaType:AVMediaTypeVideo outputSettings:vidOpts];
	
	NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
														   [NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, nil];
	
	AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
								sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary];
	
	
	//writer.movieFragmentInterval = CMTimeMake(5, 1);
writer.movieFragmentInterval = CMTimeMakeWithSeconds(10, 1000000000);
	[writer addInput:writerInput];
	
	
	if (![writer startWriting]) {
		NSLog(@"BOO");
	}
	[writer startSessionAtSourceTime:kCMTimeZero];

	self.writer = writer;
	self.adaptor = adaptor;
	self.q = dispatch_queue_create("blerg", DISPATCH_QUEUE_SERIAL);

	
	
	UIImage *image = [UIImage imageNamed:@"Cosmos09.jpg"];
	
	__block int i = 0;

	CVPixelBufferRef img = [AppDelegate pixelBufferFromCGImage:image.CGImage];
	
	[writerInput requestMediaDataWhenReadyOnQueue:self.q usingBlock:^{
		if (![adaptor appendPixelBuffer:img withPresentationTime:CMTimeMake(i++, 30)]) {
			NSLog(@"zzz %@", writer.error);
		}
	}];
	
//	[adaptor appendPixelBuffer:[AppDelegate pixelBufferFromCGImage:image.CGImage] withPresentationTime:kCMTimeZero];
	if (false) {
	[writer finishWritingWithCompletionHandler:^{
		NSLog(@"fini");
	}];
	}
	
	return YES;
}

+ (CVPixelBufferRef)pixelBufferFromCGImage:(CGImageRef)image
{
	CGSize frameSize = CGSizeMake(CGImageGetWidth(image), CGImageGetHeight(image));
	NSDictionary *options = @{
							  (__bridge NSString *)kCVPixelBufferCGImageCompatibilityKey: @(NO),
							  (__bridge NSString *)kCVPixelBufferCGBitmapContextCompatibilityKey: @(NO)
							  };
	CVPixelBufferRef pixelBuffer;
	CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, frameSize.width,
										  frameSize.height,  kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef) options,
										  &pixelBuffer);
	if (status != kCVReturnSuccess) {
		return NULL;
	}
	
	CVPixelBufferLockBaseAddress(pixelBuffer, 0);
	void *data = CVPixelBufferGetBaseAddress(pixelBuffer);
	CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
	CGContextRef context = CGBitmapContextCreate(data, frameSize.width, frameSize.height,
												 8, CVPixelBufferGetBytesPerRow(pixelBuffer), rgbColorSpace,
												 (CGBitmapInfo) kCGImageAlphaNoneSkipFirst);
	CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
										   CGImageGetHeight(image)), image);
	CGColorSpaceRelease(rgbColorSpace);
	CGContextRelease(context);
	CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);
	
	return pixelBuffer;
}


@end

Raising the fragment interval seems to help - I'm not getting errors with 3 seconds.

That does appear to fix the problem! Thank you!

Glad to be of help!