Someone asked me before if I knew how to do record the screen in Cocos2d as a video. I didn’t know how to record a video, so this guy sent me some codes, but his problem is that his code is recording the screen (taking screenshots) as a UIWindow. So my idea for him was to replace his screenshot code with AWScreenshot (by Manucorporat, search the Cocos2d forums for his code).
And here are the code bits:
#import <AVFoundation/AVFoundation.h>
#import <AVFoundation/AVAssetWriter.h>
#import <CoreVideo/CVPixelBuffer.h>
#import <CoreMedia/CMTime.h>#import “AWScreenshot.h”
#define FRAME_WIDTH 320
#define FRAME_HEIGHT 480
#define TIME_SCALE 60 // frames per second-(void) startScreenRecording
{
NSLog(@”start screen recording”);
// create the AVAssetWriter
NSString *moviePath = [[self pathToDocumentsDirectory] stringByAppendingPathComponent: @”video.mov”];
if ([[NSFileManager defaultManager] fileExistsAtPath:moviePath])
{ [[NSFileManager defaultManager] removeItemAtPath:moviePath error:nil];
}
NSURL *movieURL = [NSURL fileURLWithPath:moviePath];
NSError *movieError = nil;
[assetWriter release];
assetWriter = [[AVAssetWriter alloc] initWithURL:movieURL
fileType: AVFileTypeQuickTimeMovie
error: &movieError];
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)];
// start writing samples to it
[assetWriterTimer release];
assetWriterTimer = [NSTimer scheduledTimerWithTimeInterval:0.1
target:self
selector:@selector (writeSample:)
userInfo:nil
repeats:YES] ;
}-(void) stopScreenRecording
{ [assetWriterTimer invalidate];
assetWriterTimer = nil;
[assetWriter finishWriting];
NSLog (@”finished writing”);
}
As you can see startScreenRecording is calls writeSample.
-(void) writeSample: (NSTimer*) _timer
{ if (assetWriterInput.readyForMoreMediaData)
{
CVReturn cvErr = kCVReturnSuccess;
// get screenshot image!
CGImageRef image = (CGImageRef) [[self createARGBImageFromRGBAImage:[self screenshot]] CGImage];
// prepare the pixel buffer
CVPixelBufferRef pixelBuffer = NULL;
CFDataRef imageData= CGDataProviderCopyData(CGImageGetDataProvider(image));
cvErr = CVPixelBufferCreateWithBytes(kCFAllocatorDefault,
FRAME_WIDTH,
FRAME_HEIGHT,
kCVPixelFormatType_32ARGB,
(void*)CFDataGetBytePtr(imageData),
CGImageGetBytesPerRow(image),
NULL,
NULL,
NULL,
&pixelBuffer);
// 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 stopScreenRecording];
}
}
}
And the code I used to take screenshot:
– (UIImage*)screenshot
{ return [AWScreenshot takeAsImage];
}
Notice how I called [[self createARGBImageFromRGBAImage: [self screenshot]], it’s because my UIImage is a RGBAImage, while the CVPixelBuffer’s format type is kCVPixelFormatType_32ARGB, so I had to fix thing so they match or else, my video would come up in weird tints.
I found the Googled for the createARGBImageFromRGBAImage code, and here it is:
-(UIImage *) createARGBImageFromRGBAImage: (UIImage*)image
{ CGSize dimensions = [image size];
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * dimensions.width;
NSUInteger bitsPerComponent = 8;
unsigned char *rgba = malloc(bytesPerPixel * dimensions.width * dimensions.height);
unsigned char *argb = malloc(bytesPerPixel * dimensions.width * dimensions.height);
CGColorSpaceRef colorSpace = NULL;
CGContextRef context = NULL;
colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(rgba, dimensions.width, dimensions.height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrderDefault); // kCGBitmapByteOrder32Big
CGContextDrawImage(context, CGRectMake(0, 0, dimensions.width, dimensions.height), [image CGImage]);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
for (int x = 0; x < dimensions.width; x++) {
for (int y = 0; y < dimensions.height; y++) {
NSUInteger offset = ((dimensions.width * y) + x) * bytesPerPixel;
argb[offset + 0] = rgba[offset + 3];
argb[offset + 1] = rgba[offset + 0];
argb[offset + 2] = rgba[offset + 1];
argb[offset + 3] = rgba[offset + 2];
}
}
colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(argb, dimensions.width, dimensions.height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrderDefault); // kCGBitmapByteOrder32Big
CGImageRef imageRef = CGBitmapContextCreateImage(context);
image = [UIImage imageWithCGImage: imageRef];
CGImageRelease(imageRef);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
free(rgba);
free(argb);
return image;
}
And there we go, I managed to record the screen of my Cocos2d app and then save it as a video file.
My next problem is, how do I add audio to my video?
Michelle Chen 