视频转GIF的实现

/**
 *  视频转GIF
 *  @param videoURL videoURL
 *  @param beginSecond 录制开始时间
 *  @param durationSecond 录制持续时间
 *  @param successBlock 成功
 */
+ (void)thumbnailImageForVideo:(NSURL *)videoURL begin:(int)beginSecond Duration:(int)durationSecond responseSuccess:(void (^)(NSArray *resultArr))successBlock{
NSMutableArray *imgArr = [[NSMutableArray alloc] init];
AVAsset *myAsset = [[AVURLAsset alloc] initWithURL:videoURL options:nil];
NSParameterAssert(myAsset);


CMTime cmtime = myAsset.duration; //视频时间信息结构体
CMTimeScale fps = 10;//生成gif的帧率 视频帧率myAsset.duration.timescale  fps
Float64 durationSeconds = CMTimeGetSeconds(cmtime); //视频总秒数
NSMutableArray *times = [NSMutableArray array];

float count = durationSecond*fps;
for (int i = 0; i < count ; i++) {
    CMTime timeFrame = CMTimeMake(beginSecond*fps+i, fps); //第i帧 帧率
    NSValue *timeValue = [NSValue valueWithCMTime:timeFrame];
    [times addObject:timeValue];
}

AVAssetImageGenerator *imgGenerator = [[AVAssetImageGenerator alloc] initWithAsset:myAsset]; //防止时间出现偏差
imgGenerator.requestedTimeToleranceBefore = kCMTimeZero;
imgGenerator.requestedTimeToleranceAfter = kCMTimeZero;

[imgGenerator generateCGImagesAsynchronouslyForTimes:times completionHandler:^(CMTime requestedTime, CGImageRef _Nullable image, CMTime actualTime, AVAssetImageGeneratorResult result, NSError * _Nullable error) {
     if (image){
         [CATransaction begin];
         [CATransaction setDisableActions:YES];
         UIImage *img = [UIImage imageWithCGImage:image];
         [imgArr addObject:img];
         [CATransaction commit];
     }
     if (result == AVAssetImageGeneratorSucceeded) {
         // Do something interesting with the image.
         if (imgArr.count==times.count) {
             [self makeGifImgViewAction:imgArr fps:1/fps];
             successBlock(imgArr);
             return ;
         }
     }
    
     if (result == AVAssetImageGeneratorFailed) {
         DDLogDebug(@"Failed with error: %@", [error localizedDescription]);
     }
     if (result == AVAssetImageGeneratorCancelled) {
         DDLogDebug(@"Canceled");
     }
 }];

}

// 生成gif图片
+(void)makeGifImgViewAction:(NSArray*)imageArr fps:(float)fps{
 //gif的制作
//图像目标
CGImageDestinationRef destination;

//创建输出路径
NSArray *document = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentStr = [document objectAtIndex:0];
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *textDirectory = [documentStr stringByAppendingPathComponent:@"gif"];
[fileManager createDirectoryAtPath:textDirectory withIntermediateDirectories:YES attributes:nil error:nil];
NSString *path = [textDirectory stringByAppendingPathComponent:@"test101.gif"];


DDLogDebug(@"%@",path);

//创建CFURL对象
/*
 CFURLCreateWithFileSystemPath(CFAllocatorRef allocator, CFStringRef filePath, CFURLPathStyle pathStyle, Boolean isDirectory)
 
 allocator : 分配器,通常使用kCFAllocatorDefault
 filePath : 路径
 pathStyle : 路径风格,我们就填写kCFURLPOSIXPathStyle 更多请打问号自己进去帮助看
 isDirectory : 一个布尔值,用于指定是否filePath被当作一个目录路径解决时相对路径组件
 */
CFURLRef url = CFURLCreateWithFileSystemPath (
                                              kCFAllocatorDefault,
                                              (CFStringRef)path,
                                              kCFURLPOSIXPathStyle,
                                              false);

//通过一个url返回图像目标 kUTTypeGIF  CFStringRef

destination = CGImageDestinationCreateWithURL(url, kUTTypeGIF, imageArr.count, NULL);

//设置gif的信息,播放间隔时间,基本数据,和delay时间
NSDictionary *frameProperties = [NSDictionary
                                 dictionaryWithObject:[NSMutableDictionary dictionaryWithObjectsAndKeys:
                                                       [NSNumber numberWithFloat:fps],
                                                       (NSString *)kCGImagePropertyGIFDelayTime,
                                                       nil]
                                 forKey:(NSString *)kCGImagePropertyGIFDictionary];

//设置gif信息
NSMutableDictionary *dict = [NSMutableDictionary dictionaryWithCapacity:2];
//
[dict setObject:[NSNumber numberWithBool:YES] forKey:(NSString*)kCGImagePropertyGIFHasGlobalColorMap];

[dict setObject:(NSString *)kCGImagePropertyColorModelRGB forKey:(NSString *)kCGImagePropertyColorModel];

[dict setObject:[NSNumber numberWithInt:8] forKey:(NSString*)kCGImagePropertyDepth];

[dict setObject:[NSNumber numberWithInt:0] forKey:(NSString *)kCGImagePropertyGIFLoopCount];
NSDictionary *gifProperties = [NSDictionary dictionaryWithObject:dict
                                                          forKey:(NSString *)kCGImagePropertyGIFDictionary];
//合成gif
for (UIImage* dImg in imageArr)
{
    CGImageDestinationAddImage(destination, dImg.CGImage, (__bridge CFDictionaryRef)frameProperties);
}
CGImageDestinationSetProperties(destination, (__bridge CFDictionaryRef)gifProperties);
CGImageDestinationFinalize(destination);
CFRelease(destination);


DDLogDebug(@"animated GIF file created at %@", path);

NSData *data = [NSData dataWithContentsOfFile:path];
NSDictionary *metadata = @{@"UTI":(__bridge NSString *)kUTTypeGIF};
// 保存到本地相册
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library writeImageDataToSavedPhotosAlbum:data metadata:metadata completionBlock:^(NSURL *assetURL, NSError *error) {
    
    if (error) {
        DDLogDebug(@"写数据失败:%@",error);
    }else{
        
        [library assetForURL:assetURL resultBlock:^(ALAsset *asset) {
            DDLogDebug(@"成功保存到相册");
        } failureBlock:^(NSError *error) {
            DDLogDebug(@"gif保存到的ALAsset有问题, URL:%@,err:%@",assetURL,error);
        }];
    }
}] ;

}

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