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我從前兩週面臨一個問題。其實我正在開發一款iPad應用程序。我想在其中進行註釋並對該註釋進行屏幕錄製。註釋部分工作正常，但是當我開始錄製時會出現問題。問題在於它失去了平滑性，並在屏幕錄製過程中出現滯後現象。對於屏幕錄製，我正在使用AVAsset Writer。代碼對於註釋和屏幕錄製都很好......但我不知道問題出在哪裏？在ipad上錄製屏幕
我的截圖大小爲（1050,650）
我應該使用大中央調度來解決這個問題？？？ 任何人可以幫助我解決了我的問題.....
PLZ plz幫助我....
我的代碼
// 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");
}