iphone ios 视频特效 将图像插入到视频中（转）

如果对av foundation 不熟悉得话，建议先看看wwdc 2010 关于av foundation得讲座。http://blog.csdn.net/linzhiji/article/details/6752722

- (CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image andSize:(CGSize) size
{
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, (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,
kCGImageAlphaNoneSkipFirst);
NSParameterAssert(context);
CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);

CVPixelBufferUnlockBaseAddress(pxbuffer, 0);

return pxbuffer;
}

- (void) writeImages:(NSArray *)imagesArray ToMovieAtPath:(NSString *) path withSize:(CGSize) size
inDuration:(float)duration byFPS:(int32_t)fps{
//Wire the writer:
NSError *error = nil;
AVAssetWriter *videoWriter = [[[AVAssetWriter alloc] initWithURL:[NSURL fileURLWithPath:path]
fileType:AVFileTypeQuickTimeMovie
error:&error] autorelease];
NSParameterAssert(videoWriter);

NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:size.width], AVVideoWidthKey,
[NSNumber numberWithInt:size.height], AVVideoHeightKey,
nil];

AVAssetWriterInput* videoWriterInput = [[AVAssetWriterInput
assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings] retain];

AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoWriterInput
sourcePixelBufferAttributes:nil];
NSParameterAssert(videoWriterInput);
NSParameterAssert([videoWriter canAddInput:videoWriterInput]);
[videoWriter addInput:videoWriterInput];

//Start a session:
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];

//Write some samples:
CVPixelBufferRef buffer = NULL;

int frameCount = 0;

int imagesCount = [imagesArray count];
float averageTime = duration/imagesCount;
int averageFrame = (int)(averageTime * fps);

for(UIImage * img in imagesArray)
{
buffer = [self pixelBufferFromCGImage:[img CGImage] andSize:size];

BOOL append_ok = NO;
int j = 0;
while (!append_ok && j < 30)
{
if (adaptor.assetWriterInput.readyForMoreMediaData)
{
printf("appending %d attemp %d\n", frameCount, j);

CMTime frameTime = CMTimeMake(frameCount,(int32_t) fps);
float frameSeconds = CMTimeGetSeconds(frameTime);
NSLog(@"frameCount:%d,kRecordingFPS:%d,frameSeconds:%f",frameCount,fps,frameSeconds);
append_ok = [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];

if(buffer)
[NSThread sleepForTimeInterval:0.05];
}
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", frameCount, j);
}

frameCount = frameCount + averageFrame;
}

//Finish the session:
[videoWriterInput markAsFinished];
[videoWriter finishWriting];
NSLog(@"finishWriting");
}