Problem
My AVAssetWriter is failing after appending 5 or so images to it using a AVAssetWriterInputPixelBufferAdaptor, and I have no idea why.
Details
This popular question helped but isn't working for my needs:
How do I export UIImage array as a movie?
Everything works as planned, I even delay the assetWriterInput until it can handle more media. But for some reason, it always fails after 5 or so images. The images I'm using are extracted frames from a GIF
Code
Here is my iteration code:
-(void)writeImageData
{
__block int i = 0;
videoQueue = dispatch_queue_create("com.videoQueue", DISPATCH_QUEUE_SERIAL);
[self.writerInput requestMediaDataWhenReadyOnQueue:dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0) usingBlock:^{
while (self.writerInput.readyForMoreMediaData) {
if (i >= self.imageRefs.count){
[self endSession];
videoQueue = nil;
[self saveToLibraryWithCompletion:^{
NSLog(@"Saved");
}];
break;
}
if (self.writerInput.readyForMoreMediaData){
CGImageRef imageRef = (__bridge CGImageRef)self.imageRefs[i];
CVPixelBufferRef buffer = [self pixelBufferFromCGImageRef:imageRef];
CGFloat timeScale = (CGFloat)self.imageRefs.count / self.originalDuration;
BOOL accepted = [self.adaptor appendPixelBuffer:buffer withPresentationTime:CMTimeMake(i, timeScale)];
CVBufferRelease(buffer);
if (!accepted){
NSLog(@"Buffer did not add %@, index %d, timescale %f", self.writer.error, i, timeScale);
}else{
NSLog(@"Buffer did nothing wrong");
}
i++;
}
}
}];
}
My other bits of code match the code from the Link above. This is only slightly different:
-(CVPixelBufferRef)pixelBufferFromCGImageRef:(CGImageRef)image
{
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
nil];
CVPixelBufferRef pxbuffer = NULL;
CGFloat width = 640;
CGFloat height = 640;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, width,
height, kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef) options,
&pxbuffer);
NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
NSParameterAssert(pxdata != NULL);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, width,
height, 8, 4*width, rgbColorSpace,
kCGImageAlphaNoneSkipFirst);
NSParameterAssert(context);
CGContextDrawImage(context, CGRectMake(0, 0, width,
height), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}
