iOS 录制视频MOV格式转MP4

使用UIImagePickerController系统控制器录制视频时，默认生成的格式是MOV,如果要转成MP4格式的，我们需要使用AVAssetExportSession;

支持转换的视频质量：低，中，高，640*480，720p,1080p等

如下代码片段转换

- (void)mov2mp4:(NSURL *)movUrl
{
    AVURLAsset *avAsset = [AVURLAsset URLAssetWithURL:movUrl options:nil];
    NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:avAsset];
    /**
     AVAssetExportPresetMediumQuality 表示视频的转换质量，
     */
    if ([compatiblePresets containsObject:AVAssetExportPresetMediumQuality]) {
        AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:avAsset presetName:AVAssetExportPresetMediumQuality];

        //转换完成保存的文件路径
        NSString * resultPath = [NSHomeDirectory() stringByAppendingFormat:@"/Documents/output-%@.mp4",@"cvt"];

        exportSession.outputURL = [NSURL fileURLWithPath:resultPath];

        //要转换的格式，这里使用 MP4
        exportSession.outputFileType = AVFileTypeMPEG4;

        //转换的数据是否对网络使用优化
        exportSession.shouldOptimizeForNetworkUse = YES;

        //异步处理开始转换
        [exportSession exportAsynchronouslyWithCompletionHandler:^(void)

         {
             //转换状态监控
             switch (exportSession.status) {
                 case AVAssetExportSessionStatusUnknown:
                     NSLog(@"AVAssetExportSessionStatusUnknown");
                     break;

                 case AVAssetExportSessionStatusWaiting:
                     NSLog(@"AVAssetExportSessionStatusWaiting");
                     break;

                 case AVAssetExportSessionStatusExporting:
                     NSLog(@"AVAssetExportSessionStatusExporting");
                     break;
                 case AVAssetExportSessionStatusFailed:
                     NSLog(@"AVAssetExportSessionStatusFailed");
                     break;
                 case AVAssetExportSessionStatusCancelled:
                     NSLog(@"AVAssetExportSessionStatusCancelled");
                     break;

                 case AVAssetExportSessionStatusCompleted:
                 {
                     //转换完成
                     NSLog(@"AVAssetExportSessionStatusCompleted");

                     //测试使用，保存在手机相册里面
                     ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init];
                     [assetLibrary writeVideoAtPathToSavedPhotosAlbum:exportSession.outputURL completionBlock:^(NSURL *assetURL, NSError *error){
                         if (error) {
                             NSLog(@"%@",error);
                         }
                     }];
                     break;
                 }
             }

         }];  

    }  

}

完整的调用以及转换代码

#import <AssetsLibrary/AssetsLibrary.h>
#import <MobileCoreServices/MobileCoreServices.h>
#import <AVFoundation/AVFoundation.h>

@interface ViewController ()<UIImagePickerControllerDelegate,UINavigationControllerDelegate>

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

}

- (IBAction)startCampVD:(id)sender {

    UIImagePickerController *pickerCon = [[UIImagePickerController alloc]init];
    pickerCon.sourceType = UIImagePickerControllerSourceTypeCamera;
    pickerCon.mediaTypes = @[(NSString *)kUTTypeMovie];//设定相机为视频
    pickerCon.cameraDevice = UIImagePickerControllerCameraDeviceFront;//设置相机后摄像头
    pickerCon.videoMaximumDuration = ;//最长拍摄时间
    pickerCon.videoQuality = UIImagePickerControllerQualityType640x480;//拍摄质量
    pickerCon.allowsEditing = NO;//是否可编辑
    pickerCon.delegate = self;

    [self presentViewController:pickerCon animated:YES completion:nil];

}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

    NSLog(@"视频录制完成...");
    NSLog(@"%@",info);

    [self mov2mp4:[info objectForKey:UIImagePickerControllerMediaURL]];

    [self dismissViewControllerAnimated:YES completion:nil];

}

- (void)mov2mp4:(NSURL *)movUrl
{
    AVURLAsset *avAsset = [AVURLAsset URLAssetWithURL:movUrl options:nil];
    NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:avAsset];
    /**
     AVAssetExportPresetMediumQuality 表示视频的转换质量，
     */
    if ([compatiblePresets containsObject:AVAssetExportPresetMediumQuality]) {
        AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:avAsset presetName:AVAssetExportPresetMediumQuality];

        //转换完成保存的文件路径
        NSString * resultPath = [NSHomeDirectory() stringByAppendingFormat:@"/Documents/output-%@.mp4",@"cvt"];

        exportSession.outputURL = [NSURL fileURLWithPath:resultPath];

        //要转换的格式，这里使用 MP4
        exportSession.outputFileType = AVFileTypeMPEG4;

        //转换的数据是否对网络使用优化
        exportSession.shouldOptimizeForNetworkUse = YES;

        //异步处理开始转换
        [exportSession exportAsynchronouslyWithCompletionHandler:^(void)

         {
             //转换状态监控
             switch (exportSession.status) {
                 case AVAssetExportSessionStatusUnknown:
                     NSLog(@"AVAssetExportSessionStatusUnknown");
                     break;

                 case AVAssetExportSessionStatusWaiting:
                     NSLog(@"AVAssetExportSessionStatusWaiting");
                     break;

                 case AVAssetExportSessionStatusExporting:
                     NSLog(@"AVAssetExportSessionStatusExporting");
                     break;
                 case AVAssetExportSessionStatusFailed:
                     NSLog(@"AVAssetExportSessionStatusFailed");
                     break;
                 case AVAssetExportSessionStatusCancelled:
                     NSLog(@"AVAssetExportSessionStatusCancelled");
                     break;

                 case AVAssetExportSessionStatusCompleted:
                 {
                     //转换完成
                     NSLog(@"AVAssetExportSessionStatusCompleted");

                     //测试使用，保存在手机相册里面
                     ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init];
                     [assetLibrary writeVideoAtPathToSavedPhotosAlbum:exportSession.outputURL completionBlock:^(NSURL *assetURL, NSError *error){
                         if (error) {
                             NSLog(@"%@",error);
                         }
                     }];
                     break;
                 }
             }

         }];  

    }  

}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    [picker dismissViewControllerAnimated:YES completion:^{}];

    NSLog(@"视频录制取消了...");

}