Screen Recording in ipad - objective-c

Question

I Am facing a problem from last two weeks. Actually I am working on an iPad app. In which I want to do annotation and also make screen recording of that annotations. Annotation part is working fine but it gives problem when I start recording. The problem is that it losts it's smoothness and gives lags during screen recording. For Screen Recording I am using AVAsset Writer. Codes are fine for both Annotation and Screen recording.... But I don't know where is the problem??
My ScreenShot Size is (1050,650)
Should I use Grand Central Dispatch to solve this problem???
Can anybody help me to solve out my problem.....
Plz plz help me....
MY CODE
// For Annotation
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
mouseSwiped = NO;
UITouch *touch = [touches anyObject];
if ([touch tapCount] == 2)
{
drawImage.image = nil; //Double click to undo drawing.
return;
}
lastPoint = [touch locationInView:self.view];
lastPoint.y -= 20;
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
mouseSwiped = YES;
UITouch *touch = [touches anyObject];
CGPoint currentPoint = [touch locationInView:self.view];
currentPoint.y -= 20;
// UIGraphicsBeginImageContext(canvasView.frame.size);
UIGraphicsBeginImageContext(drawImage.frame.size);
[drawImage.image drawInRect:CGRectMake(0, 0, drawImage.frame.size.width,drawImage.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 10.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
lastPoint = currentPoint;
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
if ([touch tapCount] == 2)
{
drawImage.image = nil;
return;
}
if(!mouseSwiped)
{
UIGraphicsBeginImageContext(drawImage.frame.size);
[drawImage.image drawInRect:CGRectMake(0, 0, drawImage.frame.size.width,drawImage.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
CGContextFlush(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
}
//For Screen Recording
#define FRAME_WIDTH 1024
#define FRAME_HEIGHT 650
#define TIME_SCALE 600
- (UIImage*)screenshot
{
UIGraphicsBeginImageContext(drawImage.frame.size);
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return viewImage;
}
-(NSURL*) pathToDocumentsDirectory {
NSString* outputPath = [[NSString alloc] initWithFormat:#"%#/%#", [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0], #"output.mov"];
outputURL = [[NSURL alloc] initFileURLWithPath:outputPath];
NSFileManager* fileManager = [NSFileManager defaultManager];
if ([fileManager fileExistsAtPath:outputPath]) {
NSError* error;
if ([fileManager removeItemAtPath:outputPath error:&error] == NO) {
NSLog(#"Could not delete old recording file at path: %#", outputPath);
}
}
[outputPath release];
return [outputURL autorelease];
}
-(void) writeSample: (NSTimer*) _timer
{
if (assetWriterInput.readyForMoreMediaData) {
// CMSampleBufferRef sample = nil;
CVReturn cvErr = kCVReturnSuccess;
// get screenshot image!
CGImageRef image = (CGImageRef) [[self screenshot] CGImage];
NSLog (#"made screenshot");
// prepare the pixel buffer
CVPixelBufferRef pixelBuffer = NULL;
CFDataRef imageData= CGDataProviderCopyData(CGImageGetDataProvider(image));
NSLog (#"copied image data");
cvErr = CVPixelBufferCreateWithBytes(kCFAllocatorDefault,
FRAME_WIDTH,
FRAME_HEIGHT,
kCVPixelFormatType_32BGRA,
(void*)CFDataGetBytePtr(imageData),
CGImageGetBytesPerRow(image),
NULL,
NULL,
NULL,
&pixelBuffer);
NSLog (#"CVPixelBufferCreateWithBytes returned %d", cvErr);
// calculate the time
CFAbsoluteTime thisFrameWallClockTime = CFAbsoluteTimeGetCurrent();
CFTimeInterval elapsedTime = thisFrameWallClockTime - firstFrameWallClockTime;
NSLog (#"elapsedTime: %f", elapsedTime);
CMTime presentationTime = CMTimeMake (elapsedTime * TIME_SCALE, TIME_SCALE);
// write the sample
BOOL appended = [assetWriterPixelBufferAdaptor appendPixelBuffer:pixelBuffer withPresentationTime:presentationTime];
if (appended) {
NSLog (#"appended sample at time %lf", CMTimeGetSeconds(presentationTime));
} else {
NSLog (#"failed to append");
[self stopRecording];
}
}
}
-(void) startRecording {
movieURL = [self pathToDocumentsDirectory];
NSLog(#"path=%#",movieURL);
movieError = nil;
[assetWriter release];
assetWriter = [[AVAssetWriter alloc] initWithURL:movieURL
fileType: AVFileTypeQuickTimeMovie
error: &movieError];
[self writer];
// start writing samples to it
NSDate* start = [NSDate date];
frameRate=40.0f;
float processingSeconds = [[NSDate date] timeIntervalSinceDate:start];
delayRemaining = (1.0 / self.frameRate) - processingSeconds;
[assetWriterTimer release];
assetWriterTimer = [NSTimer scheduledTimerWithTimeInterval:delayRemaining > 0.0 ? delayRemaining : 0.01
target:self
selector:#selector (writeSample:)
userInfo:nil
repeats:YES] ;
}
-(void)writer
{
NSDictionary *assetWriterInputSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:FRAME_WIDTH], AVVideoWidthKey,
[NSNumber numberWithInt:FRAME_HEIGHT], AVVideoHeightKey,
nil];
assetWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType: AVMediaTypeVideo
outputSettings:assetWriterInputSettings];
assetWriterInput.expectsMediaDataInRealTime = YES;
[assetWriter addInput:assetWriterInput];
[assetWriterPixelBufferAdaptor release];
assetWriterPixelBufferAdaptor = [[AVAssetWriterInputPixelBufferAdaptor alloc]
initWithAssetWriterInput:assetWriterInput
sourcePixelBufferAttributes:nil];
[assetWriter startWriting];
firstFrameWallClockTime = CFAbsoluteTimeGetCurrent();
[assetWriter startSessionAtSourceTime: CMTimeMake(0, TIME_SCALE)];
}
-(void) stopRecording {
[assetWriterTimer invalidate];
assetWriterTimer = nil;
[assetWriter finishWriting];
NSLog (#"finished writing");
}

Answer 1

Simplest approach is to try lower frame rates.