第二步：本地视频生成GIF图
/**
生成GIF图片
@param videoURL 视频的路径URL
@param loopCount 播放次数
@param time 每帧的时间间隔 默认0.25s
@param imagePath 存放GIF图片的文件路径
@param completeBlock 完成的回调
*/
#pragma mark--制作GIF
- (void)createGIFfromURL:(NSURL*)videoURL loopCount:(int)loopCount delayTime:(CGFloat )time gifImagePath:(NSString *)imagePath complete:(CompleteBlock)completeBlock {
_completeBlock =completeBlock;
float delayTime = time?:0.25;
// Create properties dictionaries
NSDictionary *fileProperties = [self filePropertiesWithLoopCount:loopCount];
NSDictionary *frameProperties = [self framePropertiesWithDelayTime:delayTime];
AVURLAsset *asset = [AVURLAsset assetWithURL:videoURL];
float videoWidth = [[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].width;
float videoHeight = [[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] naturalSize].height;
GIFSize optimalSize = GIFSizeMedium;
if (videoWidth >= 1200 || videoHeight >= 1200)
optimalSize = GIFSizeVeryLow;
else if (videoWidth >= 800 || videoHeight >= 800)
optimalSize = GIFSizeLow;
else if (videoWidth >= 400 || videoHeight >= 400)
optimalSize = GIFSizeMedium;
else if (videoWidth < 400|| videoHeight < 400)
optimalSize = GIFSizeHigh;
// Get the length of the video in seconds
float videoLength = (float)asset.duration.value/asset.duration.timescale;
int framesPerSecond = 4;
int frameCount = videoLength*framesPerSecond;
// How far along the video track we want to move, in seconds.
float increment = (float)videoLength/frameCount;
// Add frames to the buffer
NSMutableArray *timePoints = [NSMutableArray array];
for (int currentFrame = 0; currentFrame<frameCount; ++currentFrame) {
float seconds = (float)increment * currentFrame;
CMTime time = CMTimeMakeWithSeconds(seconds, [timeInterval intValue]);
[timePoints addObject:[NSValue valueWithCMTime:time]];
}
//completion block
NSURL *gifURL = [self createGIFforTimePoints:timePoints fromURL:videoURL fileProperties:fileProperties frameProperties:frameProperties gifImagePath:imagePath frameCount:frameCount gifSize:_gifSize?:GIFSizeMedium];
if (_completeBlock) {
// Return GIF URL
_completeBlock(_error,gifURL);
}
}
经过上面两步，就可以生成本地的视频和GIF图了，存储在沙盒即可。贴上两步所用到的方法：
#pragma mark - Base methods
- (NSURL *)createGIFforTimePoints:(NSArray *)timePoints fromURL:(NSURL *)url fileProperties:(NSDictionary *)fileProperties frameProperties:(NSDictionary *)frameProperties gifImagePath:(NSString *)imagePath frameCount:(int)frameCount gifSize:(GIFSize)gifSize{
NSURL *fileURL = [NSURL fileURLWithPath:imagePath];
if (fileURL == nil)
return nil;
CGImageDestinationRef destination = CGImageDestinationCreateWithURL((__bridge CFURLRef)fileURL, kUTTypeGIF , frameCount, NULL);
CGImageDestinationSetProperties(destination, (CFDictionaryRef)fileProperties);
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:url options:nil];
AVAssetImageGenerator *generator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
generator.appliesPreferredTrackTransform = YES;
CMTime tol = CMTimeMakeWithSeconds([tolerance floatValue], [timeInterval intValue]);
generator.requestedTimeToleranceBefore = tol;
generator.requestedTimeToleranceAfter = tol;
NSError *error = nil;
CGImageRef previousImageRefCopy = nil;
for (NSValue *time in timePoints) {
CGImageRef imageRef;
#if TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR
imageRef = (float)gifSize/10 != 1 ? createImageWithScale([generator copyCGImageAtTime:[time CMTimeValue] actualTime:nil error:&error], (float)gifSize/10) : [generator copyCGImageAtTime:[time CMTimeValue] actualTime:nil error:&error];
#elif TARGET_OS_MAC
imageRef = [generator copyCGImageAtTime:[time CMTimeValue] actualTime:nil error:&error];
#endif
if (error) {
_error =error;
logdebug(@"Error copying image: %@", error);
return nil;
}
if (imageRef) {
CGImageRelease(previousImageRefCopy);
previousImageRefCopy = CGImageCreateCopy(imageRef);
} else if (previousImageRefCopy) {
imageRef = CGImageCreateCopy(previousImageRefCopy);
} else {
_error =[NSError errorWithDomain:NSStringFromClass([self class]) code:0 userInfo:@{NSLocalizedDescriptionKey:@"Error copying image and no previous frames to duplicate"}];
logdebug(@"Error copying image and no previous frames to duplicate");
return nil;
}
CGImageDestinationAddImage(destination, imageRef, (CFDictionaryRef)frameProperties);
CGImageRelease(imageRef);
}
CGImageRelease(previousImageRefCopy);
// Finalize the GIF
if (!CGImageDestinationFinalize(destination)) {
_error =error;
logdebug(@"Failed to finalize GIF destination: %@", error);
if (destination != nil) {
CFRelease(destination);
}
return nil;
}
CFRelease(destination);
return fileURL;
}
#pragma mark - Helpers
CGImageRef createImageWithScale(CGImageRef imageRef, float scale) {
#if TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR
CGSize newSize = CGSizeMake(CGImageGetWidth(imageRef)*scale, CGImageGetHeight(imageRef)*scale);
CGRect newRect = CGRectIntegral(CGRectMake(0, 0, newSize.width, newSize.height));
UIGraphicsBeginImageContextWithOptions(newSize, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
if (!context) {
return nil;
}
// Set the quality level to use when rescaling
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGAffineTransform flipVertical = CGAffineTransformMake(1, 0, 0, -1, 0, newSize.height);
CGContextConcatCTM(context, flipVertical);
// Draw into the context; this scales the image
CGContextDrawImage(context, newRect, imageRef);
//Release old image
CFRelease(imageRef);
// Get the resized image from the context and a UIImage
imageRef = CGBitmapContextCreateImage(context);
UIGraphicsEndImageContext();
#endif
return imageRef;
}
#pragma mark - Properties
- (NSDictionary *)filePropertiesWithLoopCount:(int)loopCount {
return @{(NSString *)kCGImagePropertyGIFDictionary:
@{(NSString *)kCGImagePropertyGIFLoopCount: @(loopCount)}
};
}
- (NSDictionary *)framePropertiesWithDelayTime:(float)delayTime {
return @{(NSString *)kCGImagePropertyGIFDictionary:
@{(NSString *)kCGImagePropertyGIFDelayTime: @(delayTime)},
(NSString *)kCGImagePropertyColorModel:(NSString *)kCGImagePropertyColorModelRGB
};
}
