视频压缩和修改角度、大小

#import 

//调用
//_VideoFilePath:视频文件路径
NSDateFormatter *formater = [[NSDateFormatter alloc] init];//用时间给文件全名，以免重复，在测试的时候其实可以判断文件是否存在若存在，则删除，重新生成文件即可
[formater setDateFormat:@"yyyy-MM-dd-HH:mm:ss"];
NSString * resultPath = [NSHomeDirectory() stringByAppendingFormat:@"/Documents/output-%@.mov", [formater stringFromDate:[NSDate date]]];
[Toolkit lowQuailtyWithInputURL:_VideoFilePath outputURL:[NSURL fileURLWithPath:resultPath] blockHandler:^(AVAssetExportSession *session) {
        if (session.status == AVAssetExportSessionStatusCompleted)
        {
            NSLog(@"压缩完成");
        }else if (session.status == AVAssetExportSessionStatusFailed) {
            NSLog(@"压缩失败");
        }
    }];

//视频压缩
+ (void) lowQuailtyWithInputURL:(NSURL*)inputURL
                      outputURL:(NSURL*)outputURL
                   blockHandler:(void (^)(AVAssetExportSession*))handler
{
    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:inputURL options:nil];
    NSArray *tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
    AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
    
    CGAffineTransform translateToCenter;
    CGAffineTransform mixedTransform;
    AVMutableVideoComposition *waterMarkVideoComposition = [AVMutableVideoComposition videoComposition];
    waterMarkVideoComposition.frameDuration = CMTimeMake(1, 30);
    
    int degrees = [Toolkit degressFromVideoFileWithURL:inputURL];
    if (degrees == 0) {
        AVAssetExportSession *session = [[AVAssetExportSession alloc] initWithAsset:asset     presetName:AVAssetExportPresetMediumQuality];
        session.outputURL = outputURL;
        session.outputFileType = AVFileTypeQuickTimeMovie;
        [session exportAsynchronouslyWithCompletionHandler:^(void)
         {
             handler(session);
         }];
    }else{
        if(degrees == 90){
            //顺时针旋转90°
            NSLog(@"视频旋转90度,home按键在左");
            translateToCenter = CGAffineTransformMakeTranslation(videoTrack.naturalSize.height, 0.0);
            mixedTransform = CGAffineTransformRotate(translateToCenter,M_PI_2);
            waterMarkVideoComposition.renderSize = CGSizeMake(videoTrack.naturalSize.height,videoTrack.naturalSize.width);
        }else if(degrees == 180){
            //顺时针旋转180°
            NSLog(@"视频旋转180度，home按键在上");
            translateToCenter = CGAffineTransformMakeTranslation(videoTrack.naturalSize.width, videoTrack.naturalSize.height);
            mixedTransform = CGAffineTransformRotate(translateToCenter,M_PI);
            waterMarkVideoComposition.renderSize = CGSizeMake(videoTrack.naturalSize.width,videoTrack.naturalSize.height);
        }else if(degrees == 270){
            //顺时针旋转270°
            NSLog(@"视频旋转270度，home按键在右");
            translateToCenter = CGAffineTransformMakeTranslation(0.0, videoTrack.naturalSize.width);
            mixedTransform = CGAffineTransformRotate(translateToCenter,M_PI_2*3.0);
            waterMarkVideoComposition.renderSize = CGSizeMake(videoTrack.naturalSize.height,videoTrack.naturalSize.width);
        }
        
        
        AVMutableVideoCompositionInstruction *roateInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
        roateInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, [asset duration]);
        AVMutableVideoCompositionLayerInstruction *roateLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoTrack];
        
        [roateLayerInstruction setTransform:mixedTransform atTime:kCMTimeZero];
        
        roateInstruction.layerInstructions = @[roateLayerInstruction];
        //将视频方向旋转加入到视频处理中
        waterMarkVideoComposition.instructions = @[roateInstruction];
        
        AVAssetExportSession *session = [[AVAssetExportSession alloc] initWithAsset:asset     presetName:AVAssetExportPresetMediumQuality];
        session.outputURL = outputURL;
        session.videoComposition = waterMarkVideoComposition;
        session.outputFileType = AVFileTypeQuickTimeMovie;
        [session exportAsynchronouslyWithCompletionHandler:^(void)
         {
             handler(session);
         }];
    }
}

//获取视频角度
+(int)degressFromVideoFileWithURL:(NSURL *)url
{
    int degress = 0;
    
    AVAsset *asset = [AVAsset assetWithURL:url];
    NSArray *tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
    if([tracks count] > 0) {
        AVAssetTrack *videoTrack = [tracks objectAtIndex:0];
        CGAffineTransform t = videoTrack.preferredTransform;
        
        if(t.a == 0 && t.b == 1.0 && t.c == -1.0 && t.d == 0){
            // Portrait
            degress = 90;
        }else if(t.a == 0 && t.b == -1.0 && t.c == 1.0 && t.d == 0){
            // PortraitUpsideDown
            degress = 270;
        }else if(t.a == 1.0 && t.b == 0 && t.c == 0 && t.d == 1.0){
            // LandscapeRight
            degress = 0;
        }else if(t.a == -1.0 && t.b == 0 && t.c == 0 && t.d == -1.0){
            // LandscapeLeft
            degress = 180;
        }
    }
    
    return degress;
}

//获取视频文件大小
+ (CGFloat) getFileSize:(NSString *)path
{
    NSFileManager *fileManager = [[NSFileManager alloc] init];
    float filesize = -1.0;
    if ([fileManager fileExistsAtPath:path]) {
        NSDictionary *fileDic = [fileManager attributesOfItemAtPath:path error:nil];//获取文件的属性
        unsigned long long size = [[fileDic objectForKey:NSFileSize] longLongValue];
        filesize = 1.0*size/1024;
    }
    return filesize;
}