How to Animate Images while converting to Video - ios

Question

I want to animate images smoothly while converting them to video. Dispite of searching SO, I am unable to understand how to achive it. I tried changing the Rotation angle(CGAffineTransformRotation), Translations and Scaling but didn't found a way to for the smooth animations. Heres how I am converting array of photos to video :
- (void)createVideoWithArrayImages:(NSMutableArray*)images size:(CGSize)size time:(float)time output:(NSURL*)output {
//getting a random path
NSError *error;
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:output fileType:AVFileTypeMPEG4 error: &error];
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys: AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:size.width], AVVideoWidthKey,
[NSNumber numberWithInt:size.height], AVVideoHeightKey,
nil];
AVAssetWriterInput* videoWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput: videoWriterInput sourcePixelBufferAttributes:nil];
videoWriterInput.expectsMediaDataInRealTime = YES;
[videoWriter addInput: videoWriterInput];
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];
CVPixelBufferRef buffer = NULL;
//convert uiimage to CGImage.
//convert uiimage to CGImage.
NSInteger fps = 30;
int frameCount = 0;
for(UIImage *img in images) {
//for(VideoFrame * frm in imageArray)
NSLog(#"**************************************************");
//UIImage * img = frm._imageFrame;
buffer = [self videoPixelBufferFromCGImage:[img CGImage] andSize:size andAngle:(int)[images indexOfObject:img]];
double numberOfSecondsPerFrame = time / images.count;
double frameDuration = fps * numberOfSecondsPerFrame;
BOOL append_ok = NO;
int j = 0;
while (!append_ok && j < fps) {
if (adaptor.assetWriterInput.readyForMoreMediaData) {
//print out status:
NSLog(#"Processing video frame (%d,%d)",frameCount,(int)[images count]);
CMTime frameTime = CMTimeMake(frameCount * frameDuration,(int32_t) fps);
NSLog(#"Frame Time : %f", CMTimeGetSeconds(frameTime));
append_ok = [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];
if(!append_ok) {
NSError *error = videoWriter.error;
if(error!=nil) {
NSLog(#"Unresolved error %#,%#.", error, [error userInfo]);
}
}
}
else {
printf("adaptor not ready %d, %d\n", frameCount, j);
[NSThread sleepForTimeInterval:0.1];
}
j++;
}
if (!append_ok) {
printf("error appending image %d times %d\n, with error.", frameCount, j);
}
frameCount++;
NSLog(#"**************************************************");
}
[videoWriterInput markAsFinished];
[videoWriter finishWriting];
videoWriter = nil;
if(buffer != NULL)
CVPixelBufferRelease(buffer);
NSLog(#"************ write standard video successful ************");
}
Here CVPixelBufferRef is returned as follows :
- (CVPixelBufferRef)videoPixelBufferFromCGImage: (CGImageRef) image andSize:(CGSize) size andAngle:(int)angle {
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey, [NSNumber numberWithBool:YES],kCVPixelBufferCGBitmapContextCompatibilityKey, nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, size.width, size.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, size.width, size.height, 8, 4*size.width, rgbColorSpace, kCGImageAlphaPremultipliedFirst);
NSParameterAssert(context);
CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
CGContextDrawImage(context, CGRectMake(0, 0, size.width, size.height), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}
I tried adding Translations to the CVPixelBufferRef but thing didn't worked out for me. Any guide, any help would be very useful.

Answer 1

YOu don't specify what you want to achieve, but I've used AVVideoCompositionCoreAnimationTool to include animated CALayers in a AVMutableVideoComposition.
Here is the reference to that class
Hope that helps!