利用AVFoundation框架实现视频格式转码，下面以mov转mp4为例：<pre>/**mov转mp4格式*/-(void)convertMovSourceURL:(NSURL *)sourceUrl{AVURLAsset *avAsset = [AVURLAsset URLAssetWithURL:sourceUrl options:nil];NSArray *compatiblePresets=[AVAssetExportSession exportPresetsCompatibleWithAsset:avAsset];//NSLog(@"%@",compatiblePresets);if ([compatiblePresets containsObject:AVAssetExportPresetHighestQuality]) {AVAssetExportSession *exportSession=[[AVAssetExportSession alloc] initWithAsset:avAsset presetName:AVAssetExportPresetHighestQuality];NSDateFormatter *formater=[[NSDateFormatter alloc] init];//用时间给文件全名[formater setDateFormat:@"yyyyMMddHHmmss"];NSString *mp4Path=[[NSUserDefaults standardUserDefaults] objectForKey:@"kMP4FilePath"];NSString *resultPath=[NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES)[0] stringByAppendingFormat:@"/output-%@.mp4", [formater stringFromDate:[NSDate date]]];

    exportSession.outputURL=[NSURL fileURLWithPath:resultPath];exportSession.outputFileType = AVFileTypeMPEG4;exportSession.shouldOptimizeForNetworkUse = YES;[exportSession exportAsynchronouslyWithCompletionHandler:^(void){switch (exportSession.status) {case AVAssetExportSessionStatusCancelled:NSLog(@"AVAssetExportSessionStatusCancelled");break;case AVAssetExportSessionStatusUnknown:NSLog(@"AVAssetExportSessionStatusUnknown");break;case AVAssetExportSessionStatusWaiting:NSLog(@"AVAssetExportSessionStatusWaiting");break;case AVAssetExportSessionStatusExporting:NSLog(@"AVAssetExportSessionStatusExporting");break;case AVAssetExportSessionStatusCompleted:{//NSLog(@"resultPath = %@",resultPath);UIAlertController \*alert=[UIAlertController alertControllerWithTitle:@"提示" message:@"转换完成" preferredStyle:UIAlertControllerStyleAlert];UIAlertAction \*confirm=[UIAlertAction actionWithTitle:@"确定" style:UIAlertActionStyleDefault handler:nil];[alert addAction:confirm];[[UIApplication sharedApplication].keyWindow.rootViewController presentViewController:alert animated:YES completion:nil];BOOL success=[[NSFileManager defaultManager]moveItemAtPath:resultPath toPath:[mp4Path stringByAppendingPathComponent:@"1.mp4"] error:nil];if(success){NSArray \*files=[[NSFileManager defaultManager] contentsOfDirectoryAtPath:mp4Path error:nil];NSLog(@"%@",files);NSLog(@"success");}break;}case AVAssetExportSessionStatusFailed:NSLog(@"AVAssetExportSessionStatusFailed");break;}}];
}

}</pre>
用法如下：
<pre>
@interface ViewController ()<UIImagePickerControllerDelegate,UINavigationControllerDelegate>

@end

@implementation ViewController

• (void)viewDidLoad {
  [super viewDidLoad];
  self.view.backgroundColor=[UIColor whiteColor];
  self.navigationController.navigationBar.barStyle=UIBarStyleBlack;
  self.title=@"视屏格式转换";

  UIButton *btn=[[UIButton alloc]initWithFrame:CGRectMake(0, 0, 100, 50)];
  [btn setTitle:@"转换" forState:UIControlStateNormal];
  btn.backgroundColor=[UIColor orangeColor];
  [self.view addSubview:btn];
  [btn addTarget:self action:@selector(convert:) forControlEvents:UIControlEventTouchUpInside];
  btn.center=self.view.center;
  }

pragma mark - UIImagePicker

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
NSURL *videoURL=[info objectForKey:@"UIImagePickerControllerMediaURL"];
//[ProgressHUD show:@"转换中..."];
[self convertMovSourceURL:videoURL];
[picker dismissViewControllerAnimated:YES completion:nil];
}
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
[picker dismissViewControllerAnimated:YES completion:nil];
}
</pre>