How to make a movie from a set of images using UIGetScreenImage

Question

I used this method and get some images. I can successfully create a film, but my problem is that when I play a movie, it seems to play too fast, that is, the film does not have all the frames. Here is my code.

-(UIImage *)uiImageScreen { CGImageRef screen = UIGetScreenImage(); UIImage* image = [UIImage imageWithCGImage:screen]; CGImageRelease(screen); UIImageWriteToSavedPhotosAlbum(image, self,nil, nil); return image; } -(void) writeSample: (NSTimer*) _timer { if (assetWriterInput.readyForMoreMediaData) { // CMSampleBufferRef sample = nil; CVReturn cvErr = kCVReturnSuccess; // get screenshot image! CGImageRef image = (CGImageRef) [[self uiImageScreen] 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 * 600, 600); // 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"); } } } 

Then I call this method to create a movie.

 -(void)StartRecording { NSString *moviePath = [[self pathToDocumentsDirectory] stringByAppendingPathComponent:OUTPUT_FILE_NAME]; if ([[NSFileManager defaultManager] fileExistsAtPath:moviePath]) { [[NSFileManager defaultManager] removeItemAtPath:moviePath error:nil]; } NSURL *movieURL = [NSURL fileURLWithPath:moviePath]; NSLog(@"path=%@",movieURL); NSError *movieError = nil; [assetWriter release]; assetWriter = [[AVAssetWriter alloc] initWithURL:movieURL fileType: AVFileTypeQuickTimeMovie error: &movieError]; NSDictionary *assetWriterInputSettings = [NSDictionary dictionaryWithObjectsAndKeys: AVVideoCodecH264, AVVideoCodecKey, [NSNumber numberWithInt:320], AVVideoWidthKey, [NSNumber numberWithInt:480], 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, 1000)]; // start writing samples to it [assetWriterTimer release]; assetWriterTimer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector (writeSample:) userInfo:nil repeats:YES] ; } 

Answer 1

try this method ....

 if (![videoWriterInput isReadyForMoreMediaData]) { NSLog(@"Not ready for video data"); } else { @synchronized (self) { UIImage* newFrame = [self.currentScreen retain]; CVPixelBufferRef pixelBuffer = NULL; CGImageRef cgImage = CGImageCreateCopy([newFrame CGImage]); CFDataRef image = CGDataProviderCopyData(CGImageGetDataProvider(cgImage)); int status = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, avAdaptor.pixelBufferPool, &pixelBuffer); if(status != 0){ //could not get a buffer from the pool NSLog(@"Error creating pixel buffer: status=%d", status); } // set image data into pixel buffer CVPixelBufferLockBaseAddress( pixelBuffer, 0 ); uint8_t* destPixels = CVPixelBufferGetBaseAddress(pixelBuffer); CFDataGetBytes(image, CFRangeMake(0, CFDataGetLength(image)), destPixels); //XXX: will work if the pixel buffer is contiguous and has the same bytesPerRow as the input data if(status == 0){ BOOL success = [avAdaptor appendPixelBuffer:pixelBuffer withPresentationTime:time]; if (!success) NSLog(@"Warning: Unable to write buffer to video"); } //clean up [newFrame release]; CVPixelBufferUnlockBaseAddress( pixelBuffer, 0 ); CVPixelBufferRelease( pixelBuffer ); CFRelease(image); CGImageRelease(cgImage); } }