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

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1. - (CVPixelBufferRef) pixelBufferFromCGImage: (CGImageRef) image andSize:(CGSize) size  
2. {  
3.     NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:  
4.                              [NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,  
5.                              [NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,  
6.                              nil];  
7.     CVPixelBufferRef pxbuffer = NULL;  
8.       
9.     CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, size.width,  
10.                                           size.height, kCVPixelFormatType_32ARGB, (CFDictionaryRef) options,   
11.                                           &pxbuffer);  
12.     NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);  
13.       
14.     CVPixelBufferLockBaseAddress(pxbuffer, 0);  
15.     void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);  
16.     NSParameterAssert(pxdata != NULL);  
17.       
18.     CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();  
19.     CGContextRef context = CGBitmapContextCreate(pxdata, size.width,  
20.                                                  size.height, 8, 4*size.width, rgbColorSpace,   
21.                                                  kCGImageAlphaNoneSkipFirst);  
22.     NSParameterAssert(context);  
23.     CGContextConcatCTM(context, CGAffineTransformMakeRotation(0));  
24.     CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),   
25.                                            CGImageGetHeight(image)), image);  
26.     CGColorSpaceRelease(rgbColorSpace);  
27.     CGContextRelease(context);  
28.       
29.     CVPixelBufferUnlockBaseAddress(pxbuffer, 0);  
30.       
31.     return pxbuffer;  
32. }  

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1. - (void) writeImages:(NSArray *)imagesArray ToMovieAtPath:(NSString *) path withSize:(CGSize) size   
2.           inDuration:(float)duration byFPS:(int32_t)fps{  
3.     //Wire the writer:  
4.     NSError *error = nil;  
5.     AVAssetWriter *videoWriter = [[[AVAssetWriter alloc] initWithURL:[NSURL fileURLWithPath:path]   
6.                                                            fileType:AVFileTypeQuickTimeMovie  
7.                                                               error:&error] autorelease];  
8.     NSParameterAssert(videoWriter);  
9.       
10.     NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:  
11.                                    AVVideoCodecH264, AVVideoCodecKey,  
12.                                    [NSNumber numberWithInt:size.width], AVVideoWidthKey,  
13.                                    [NSNumber numberWithInt:size.height], AVVideoHeightKey,  
14.                                    nil];  
15.       
16.     AVAssetWriterInput* videoWriterInput = [[AVAssetWriterInput  
17.                                              assetWriterInputWithMediaType:AVMediaTypeVideo  
18.                                              outputSettings:videoSettings] retain];  
19.       
20.       
21.     AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor  
22.                                                      assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoWriterInput  
23.                                                      sourcePixelBufferAttributes:nil];  
24.     NSParameterAssert(videoWriterInput);  
25.     NSParameterAssert([videoWriter canAddInput:videoWriterInput]);  
26.     [videoWriter addInput:videoWriterInput];  
27.       
28.     //Start a session:  
29.     [videoWriter startWriting];  
30.     [videoWriter startSessionAtSourceTime:kCMTimeZero];  
31.       
32.     //Write some samples:  
33.     CVPixelBufferRef buffer = NULL;  
34.       
35.     int frameCount = 0;  
36.       
37.     int imagesCount = [imagesArray count];      
38.     float averageTime = duration/imagesCount;  
39.     int averageFrame = (int)(averageTime * fps);  
40.       
41.     for(UIImage * img in imagesArray)  
42.     {  
43.         buffer = [self pixelBufferFromCGImage:[img CGImage] andSize:size];  
44.           
45.         BOOL append_ok = NO;  
46.         int j = 0;  
47.         while (!append_ok && j < 30)   
48.         {  
49.             if (adaptor.assetWriterInput.readyForMoreMediaData)   
50.             {  
51.                 printf("appending %d attemp %d\n", frameCount, j);  
52.                   
53.                 CMTime frameTime = CMTimeMake(frameCount,(int32_t) fps);  
54.                 float frameSeconds = CMTimeGetSeconds(frameTime);  
55.                 NSLog(@"frameCount:%d,kRecordingFPS:%d,frameSeconds:%f",frameCount,fps,frameSeconds);  
56.                 append_ok = [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];  
57.                   
58.                 if(buffer)  
59.                     [NSThread sleepForTimeInterval:0.05];  
60.             }   
61.             else   
62.             {  
63.                 printf("adaptor not ready %d, %d\n", frameCount, j);  
64.                 [NSThread sleepForTimeInterval:0.1];  
65.             }  
66.             j++;  
67.         }  
68.         if (!append_ok) {  
69.             printf("error appending image %d times %d\n", frameCount, j);  
70.         }  
71.           
72.         frameCount = frameCount + averageFrame;  
73.     }  
74.       
75.     //Finish the session:  
76.     [videoWriterInput markAsFinished];  
77.     [videoWriter finishWriting];  
78.     NSLog(@"finishWriting");  
79. }