ios 视频/图片压缩

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    NSString*path=[[NSBundle mainBundle]pathForResource:@"dachao" ofType:@"m4v"];
    NSString*outpath=[NSString stringWithFormat:@"%@/%@/%@",NSHomeDirectory(),@"Documents",@"dachaotest"];
    NSLog(@"%@",NSHomeDirectory());
    NSDate *currentDate = [NSDate date];//获取当前时间，日期
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"YYYY/MM/dd hh:mm:ss SS"];
    NSString *dateString = [dateFormatter stringFromDate:currentDate];
    NSLog(@"dateString:%@",dateString);
    [self lowQuailtyWithInputURL:[[NSURL alloc]initFileURLWithPath:path] outputURL:[NSURL fileURLWithPath:outpath] blockHandler:^(AVAssetExportSession *session) {
        if (session.status==AVAssetExportSessionStatusCompleted) {
            NSLog(@"complete");
            NSDate *currentDate = [NSDate date];//获取当前时间，日期
            NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
            [dateFormatter setDateFormat:@"YYYY/MM/dd hh:mm:ss SS"];
            NSString *dateString = [dateFormatter stringFromDate:currentDate];
            NSLog(@"dateString:%@",dateString);
        }else{
            NSLog(@"fail");
        }
    }];
    NSLog(@"代码结束");

}
//视频压缩代码
- (void) lowQuailtyWithInputURL:(NSURL*)inputURL
                      outputURL:(NSURL*)outputURL
                   blockHandler:(void (^)(AVAssetExportSession*))handler
{
    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:inputURL options:nil];
    AVAssetExportSession *session = [[AVAssetExportSession alloc] initWithAsset:asset     presetName:AVAssetExportPresetMediumQuality];
    session.outputURL = outputURL;
　　//压缩格式
    session.outputFileType = AVFileTypeQuickTimeMovie;
    [session exportAsynchronouslyWithCompletionHandler:^(void)
     {
         handler(session);
     }];
}
//图片等比例压缩 有损压缩
-(UIImage *) imageCompressForSize:(UIImage *)sourceImage targetSize:(CGSize)size{
    UIImage *newImage = nil;
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = size.width;
    CGFloat targetHeight = size.height;
    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;
    CGPoint thumbnailPoint = CGPointMake(0.0, 0.0);
    if(CGSizeEqualToSize(imageSize, size) == NO){
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;
        if(widthFactor > heightFactor){
            scaleFactor = widthFactor;
        }
        else{
            scaleFactor = heightFactor;
        }
        scaledWidth = width * scaleFactor;
        scaledHeight = height * scaleFactor;
        if(widthFactor > heightFactor){
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
        }else if(widthFactor < heightFactor){
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }
    }
    
    UIGraphicsBeginImageContext(size);
    
    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width = scaledWidth;
    thumbnailRect.size.height = scaledHeight;
    [sourceImage drawInRect:thumbnailRect];
    newImage = UIGraphicsGetImageFromCurrentImageContext();
    
    if(newImage == nil){
        NSLog(@"scale image fail");
    }
    
    UIGraphicsEndImageContext();
    
    return newImage;
}
//图片无损压缩 
-(UIImage*)imageCompressWithImage:(UIImage*)image andQuality:(float)ql{
    NSData*data=UIImageJPEGRepresentation(image, ql);
    UIImage*newImage=[UIImage imageWithData:data];
    data=nil;
    return newImage;
}

视频压缩格式：

/*!
 @constant AVFileTypeQuickTimeMovie
 @abstract A UTI for the QuickTime movie file format.
 @discussion
 The value of this UTI is @"com.apple.quicktime-movie".
 Files are identified with the .mov and .qt extensions.
 */
AVF_EXPORT NSString *const AVFileTypeQuickTimeMovie NS_AVAILABLE(10_7, 4_0);

/*!
 @constant AVFileTypeMPEG4
 @abstract A UTI for the MPEG-4 file format.
 @discussion
 The value of this UTI is @"public.mpeg-4".
 Files are identified with the .mp4 extension.
 */
AVF_EXPORT NSString *const AVFileTypeMPEG4 NS_AVAILABLE(10_7, 4_0);

/*!
 @constant AVFileTypeAppleM4V
 @discussion
 The value of this UTI is @"com.apple.m4v-video".
 Files are identified with the .m4v extension.
 */
AVF_EXPORT NSString *const AVFileTypeAppleM4V NS_AVAILABLE(10_7, 4_0);

/*!
 @constant AVFileTypeAppleM4A
 @discussion
 The value of this UTI is @"com.apple.m4a-audio".
 Files are identified with the .m4a extension.
 */
AVF_EXPORT NSString *const AVFileTypeAppleM4A NS_AVAILABLE(10_7, 4_0);

/*!
 @constant AVFileType3GPP
 @abstract A UTI for the 3GPP file format.
 @discussion
 The value of this UTI is @"public.3gpp".
 Files are identified with the .3gp, .3gpp, and .sdv extensions.
 */
AVF_EXPORT NSString *const AVFileType3GPP NS_AVAILABLE(10_11, 4_0);

压缩视频有三级：

AVF_EXPORT NSString *const AVAssetExportPresetLowQuality        NS_AVAILABLE(10_11, 4_0);
AVF_EXPORT NSString *const AVAssetExportPresetMediumQuality     NS_AVAILABLE(10_11, 4_0);
AVF_EXPORT NSString *const AVAssetExportPresetHighestQuality    NS_AVAILABLE(10_11, 4_0);

AVF_EXPORT NSString *const AVAssetExportPreset640x480            NS_AVAILABLE(10_7, 4_0);
AVF_EXPORT NSString *const AVAssetExportPreset960x540           NS_AVAILABLE(10_7, 4_0);
AVF_EXPORT NSString *const AVAssetExportPreset1280x720          NS_AVAILABLE(10_7, 4_0);
AVF_EXPORT NSString *const AVAssetExportPreset1920x1080            NS_AVAILABLE(10_7, 5_0);
AVF_EXPORT NSString *const AVAssetExportPreset3840x2160            NS_AVAILABLE(10_10, 9_0);

经测试：

iPhone6高品质视频：一分钟 57mb   中品质压缩后：6.7mb  低品质压缩后：1.4mb  建议压缩：中品质。压缩时间大约1分钟

同品质之间的压缩不会压缩大小，时间也相对短，如对中品质视频进行中品质压缩后，其大小不变，时长大约20s；

另外：

视频的传入传出的路径为file：格式 用：[NSURL fileURLWithPath:outpath]；