可以用video设置GIF图像吗？
我正在尝试将video与GIF图像结合起来，为此我使用MainCompositionInst.animationTool = [AVVideoCompositionCoreAnimationTool videoCompositionCoreAnimationToolWithPostProcessingAsVideoLayer:videoLayer inLayer:parentLayer]; 在video层我设置了GIF图像，但不幸的是它没有动画，所以我的问题是它可以这样做吗？ 请建议我..
提前致谢。
Apple对GIF的支持相当有限。
您可以使用此代码从GIF转换为video:(使用当前代码，gif将被裁剪为480×480。对于某些分辨率，输出图像的颜色会失真，因此请尝试使用您知道可行的固定帧。
用法：
#import "SCGIFConverter.h" NSURL *tempFileURL = //create a NSURL to a tempfile for output [SCGIFConverter processGIFData:data toFilePath:tempFileURL completed:^(NSString *outputFilePath, NSError *error) { //Now you can access your tempFileURL to read the movie //outputFilePath can be 'nil' if there was a problem }];
SCGIFConverter.h
FOUNDATION_EXTERN NSString * const kGIF2MP4ConversionErrorDomain; typedef enum { kGIF2MP4ConversionErrorInvalidGIFImage = 0, kGIF2MP4ConversionErrorAlreadyProcessing, kGIF2MP4ConversionErrorBufferingFailed, kGIF2MP4ConversionErrorInvalidResolution, kGIF2MP4ConversionErrorTimedOut, } kGIF2MP4ConversionError; typedef void (^kGIF2MP4ConversionCompleted) (NSString* outputFilePath, NSError* error); @interface SCGIFConverter : NSObject + (BOOL) processGIFData: (NSData*) data toFilePath: (NSURL*) outFilePath completed: (kGIF2MP4ConversionCompleted)handler; @end
SCGIFConverter.m
#import #import #import #import "SCGIFConverter.h" #define FPS 30 NSString * const kGIF2MP4ConversionErrorDomain = @"GIF2MP4ConversionError"; @implementation SCGIFConverter + (BOOL) processGIFData: (NSData*) data toFilePath: (NSURL*) outFilePath completed: (kGIF2MP4ConversionCompleted) completionHandler { [[NSFileManager defaultManager] removeItemAtURL:outFilePath error:nil]; CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)data, NULL); CGImageMetadataRef meta = CGImageSourceCopyMetadataAtIndex(source, 0, NULL); NSLog(@"%@",meta); unsigned char *bytes = (unsigned char*)data.bytes; NSError* error = nil; if( !CGImageSourceGetStatus(source) == kCGImageStatusComplete ) { error = [NSError errorWithDomain: kGIF2MP4ConversionErrorDomain code: kGIF2MP4ConversionErrorInvalidGIFImage userInfo: nil]; CFRelease(source); completionHandler(outFilePath.absoluteString, error); return NO; } size_t sourceWidth = bytes[6] + (bytes[7]<<8), sourceHeight = bytes[8] + (bytes[9]<<8); sourceWidth = 480; sourceHeight = 480; //size_t sourceFrameCount = CGImageSourceGetCount(source); __block size_t currentFrameNumber = 0; __block Float64 totalFrameDelay = 0.f; AVAssetWriter* videoWriter = [[AVAssetWriter alloc] initWithURL: outFilePath fileType: AVFileTypeQuickTimeMovie error: &error]; if( error ) { CFRelease(source); completionHandler(outFilePath.absoluteString, error); return NO; } if( sourceWidth > 6400 || sourceWidth == 0) { CFRelease(source); error = [NSError errorWithDomain: kGIF2MP4ConversionErrorDomain code: kGIF2MP4ConversionErrorInvalidResolution userInfo: nil]; completionHandler(outFilePath.absoluteString, error); return NO; } if( sourceHeight > 4800 || sourceHeight == 0 ) { CFRelease(source); error = [NSError errorWithDomain: kGIF2MP4ConversionErrorDomain code: kGIF2MP4ConversionErrorInvalidResolution userInfo: nil]; completionHandler(outFilePath.absoluteString, error); return NO; } size_t totalFrameCount = CGImageSourceGetCount(source); if( totalFrameCount <= 0 ) { CFRelease(source); error = [NSError errorWithDomain: kGIF2MP4ConversionErrorDomain code: kGIF2MP4ConversionErrorInvalidGIFImage userInfo: nil]; completionHandler(outFilePath.absoluteString, error); return NO; } NSDictionary *videoSettings = @{ AVVideoCodecKey : AVVideoCodecH264, AVVideoWidthKey : @(sourceWidth), AVVideoHeightKey : @(sourceHeight) }; AVAssetWriterInput* videoWriterInput = [AVAssetWriterInput assetWriterInputWithMediaType: AVMediaTypeVideo outputSettings: videoSettings]; videoWriterInput.expectsMediaDataInRealTime = YES; NSAssert([videoWriter canAddInput: videoWriterInput], @"Video writer can not add video writer input"); [videoWriter addInput: videoWriterInput]; NSDictionary* attributes = @{ (NSString*)kCVPixelBufferPixelFormatTypeKey : @(kCVPixelFormatType_32ARGB), (NSString*)kCVPixelBufferWidthKey : @(sourceWidth), (NSString*)kCVPixelBufferHeightKey : @(sourceHeight), (NSString*)kCVPixelBufferCGImageCompatibilityKey : @YES, (NSString*)kCVPixelBufferCGBitmapContextCompatibilityKey : @YES }; AVAssetWriterInputPixelBufferAdaptor* adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput: videoWriterInput sourcePixelBufferAttributes: attributes]; [videoWriter startWriting]; [videoWriter startSessionAtSourceTime: CMTimeMakeWithSeconds(0, FPS)]; while(YES) { if( videoWriterInput.isReadyForMoreMediaData ) { #if DEBUG //NSLog(@"Drawing frame %lu/%lu", currentFrameNumber, totalFrameCount); #endif NSDictionary* options = @{(NSString*)kCGImageSourceTypeIdentifierHint : (id)kUTTypeGIF}; CGImageRef imgRef = CGImageSourceCreateImageAtIndex(source, currentFrameNumber, (__bridge CFDictionaryRef)options); if( imgRef ) { CFDictionaryRef propertiesT = CGImageSourceCopyProperties(source, NULL); CFDictionaryRef properties = CGImageSourceCopyPropertiesAtIndex(source, currentFrameNumber, NULL); CFDictionaryRef gifProperties = CFDictionaryGetValue(properties, kCGImagePropertyGIFDictionary); if( gifProperties ) { CVPixelBufferRef pxBuffer = [self newBufferFrom: imgRef withPixelBufferPool: adaptor.pixelBufferPool andAttributes: adaptor.sourcePixelBufferAttributes]; if( pxBuffer ) { NSNumber* delayTime = CFDictionaryGetValue(gifProperties, kCGImagePropertyGIFDelayTime); if (currentFrameNumber!=0) { totalFrameDelay += delayTime.floatValue; } CMTime time = CMTimeMakeWithSeconds(totalFrameDelay, FPS); if( ![adaptor appendPixelBuffer: pxBuffer withPresentationTime: time] ) { NSLog(@"Could not save pixel buffer!: %@", videoWriter.error); CFRelease(properties); CGImageRelease(imgRef); CVBufferRelease(pxBuffer); break; } CVBufferRelease(pxBuffer); } } if( properties ) CFRelease(properties); CGImageRelease(imgRef); currentFrameNumber++; } else { //was no image returned -> end of file? [videoWriterInput markAsFinished]; void (^videoSaveFinished)(void) = ^{ AVAssetWriter * retainedVideoWriter = videoWriter; completionHandler(outFilePath.absoluteString, nil); retainedVideoWriter = nil; }; if( [videoWriter respondsToSelector: @selector(finishWritingWithCompletionHandler:)]) { [videoWriter finishWritingWithCompletionHandler: videoSaveFinished]; } else { [videoWriter finishWriting]; videoSaveFinished(); } break; } } else { //NSLog(@"Was not ready..."); [NSThread sleepForTimeInterval: 0.1]; } }; CFRelease(source); return YES; }; + (CVPixelBufferRef) newBufferFrom: (CGImageRef) frame withPixelBufferPool: (CVPixelBufferPoolRef) pixelBufferPool andAttributes: (NSDictionary*) attributes { NSParameterAssert(frame); size_t width = 480;//CGImageGetWidth(frame); size_t height = 480;//CGImageGetHeight(frame); size_t frameHeight = height; size_t frameWidth = CGImageGetWidth(frame)*height/CGImageGetHeight(frame); if (frameWidthwidth) { CGFloat factor = MAX(width/frameWidth,1-relax); frameWidth*=factor; } if (frameHeight>height) { CGFloat factor = MAX(height/frameHeight,1-relax); frameHeight*=factor; } size_t bpc = 8; CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CVPixelBufferRef pxBuffer = NULL; CVReturn status = kCVReturnSuccess; if( pixelBufferPool ) status = CVPixelBufferPoolCreatePixelBuffer(kCFAllocatorDefault, pixelBufferPool, &pxBuffer); else { status = CVPixelBufferCreate(kCFAllocatorDefault, width, height, kCVPixelFormatType_32ARGB, (__bridge CFDictionaryRef)attributes, &pxBuffer); } NSAssert(status == kCVReturnSuccess, @"Could not create a pixel buffer"); CVPixelBufferLockBaseAddress(pxBuffer, 0); void *pxData = CVPixelBufferGetBaseAddress(pxBuffer); size_t bytesPerRow = CVPixelBufferGetBytesPerRow(pxBuffer); CGContextRef context = CGBitmapContextCreate(pxData, width, height, bpc, bytesPerRow, colorSpace, kCGImageAlphaNoneSkipFirst); NSAssert(context, @"Could not create a context"); CGContextDrawImage(context, CGRectMake(-(frameWidth-(CGFloat)width)/2, -(frameHeight-(CGFloat)height)/2, frameWidth, frameHeight), frame); CVPixelBufferUnlockBaseAddress(pxBuffer, 0); CGContextRelease(context); CGColorSpaceRelease(colorSpace); return pxBuffer; } @end