使用AVAssetExportSession无法裁剪视频

Question

我想剪辑一个视频：

-(void)trimVideo:(NSURL*)outputURL
{
    //[[NSFileManager defaultManager] removeItemAtURL:outputURL error:nil];
    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:outputURL options:nil];
    AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetLowQuality];

    NSString * outputFilePath = NSHomeDirectory();
    outputFilePath = [outputFilePath stringByAppendingPathComponent:@"Library"];
    outputFilePath = [outputFilePath stringByAppendingPathComponent:@"temp.mov"];
    NSURL * outputFileUrl = [NSURL fileURLWithPath:outputFilePath];

    exportSession.outputURL =  outputFileUrl;
    exportSession.shouldOptimizeForNetworkUse = YES;
    exportSession.outputFileType = AVFileTypeMPEG4;
    CMTime start = CMTimeMakeWithSeconds(1.0, 600);
    CMTime duration = CMTimeMakeWithSeconds(3.0, 600);
    CMTimeRange range = CMTimeRangeMake(start, duration);
    exportSession.timeRange = range;
    [exportSession exportAsynchronouslyWithCompletionHandler:^(void)
     {
         NSLog(@"Export Complete %d %@", exportSession.status, exportSession.error);
         //[exportSession release];
     }];
}

但是我遇到了错误：

Export Complete 4 Error Domain=AVFoundationErrorDomain Code=-11823 "Cannot Save" UserInfo=0x2008f420 {NSLocalizedRecoverySuggestion=Try saving again., NSLocalizedDescription=Cannot Save}

不太确定如何解决。

- Sheehan Alam

Answer 1

这个方法很管用：

-(void)trimVideo:(NSURL*)videoToTrimURL
{
    //[[NSFileManager defaultManager] removeItemAtURL:outputURL error:nil];
    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:videoToTrimURL options:nil];
    AVAssetExportSession *exportSession = [[AVAssetExportSession alloc] initWithAsset:asset presetName:AVAssetExportPresetHighestQuality];

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *outputURL = paths[0];
    NSFileManager *manager = [NSFileManager defaultManager];
    [manager createDirectoryAtPath:outputURL withIntermediateDirectories:YES attributes:nil error:nil];
    outputURL = [outputURL stringByAppendingPathComponent:@"output.mp4"];
    // Remove Existing File
    [manager removeItemAtPath:outputURL error:nil];


    exportSession.outputURL = [NSURL fileURLWithPath:outputURL];
    exportSession.shouldOptimizeForNetworkUse = YES;
    exportSession.outputFileType = AVFileTypeQuickTimeMovie;
    CMTime start = CMTimeMakeWithSeconds(1.0, 600);
    CMTime duration = CMTimeMakeWithSeconds(3.0, 600);
    CMTimeRange range = CMTimeRangeMake(start, duration);
    exportSession.timeRange = range;
    [exportSession exportAsynchronouslyWithCompletionHandler:^(void)
     {         
         switch (exportSession.status) {
             case AVAssetExportSessionStatusCompleted:
                 [self writeVideoToPhotoLibrary:[NSURL fileURLWithPath:outputURL]];
                 NSLog(@"Export Complete %d %@", exportSession.status, exportSession.error);
                break;
             case AVAssetExportSessionStatusFailed:
                 NSLog(@"Failed:%@",exportSession.error);
                 break;
             case AVAssetExportSessionStatusCancelled:
                 NSLog(@"Canceled:%@",exportSession.error);
                 break;
             default:
                 break;
         }

         //[exportSession release];
     }];
}

- Sheehan Alam

---

出现错误：-- [manager writeVideoToPhotoLibrary:[NSURL fileURLWithPath:outputURL]]; - Prince Kumar Sharma

你好Khoool，你需要在你的类中创建这个方法。 -(void)writeVideoToPhotoLibrary:(NSURL *)nsurlToSave{ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init]; NSURL *recordedVideoURL= nsurlToSave; if ([library videoAtPathIsCompatibleWithSavedPhotosAlbum:recordedVideoURL]) { [library writeVideoAtPathToSavedPhotosAlbum:recordedVideoURL completionBlock:^(NSURL *assetURL, NSError *error){} ]; } [library release] } - TurboManolo

终于过了几个小时！你解决了这个问题。fileURLWithPath 真是太神奇了。 - jgvb

问题在于尝试向一个已经存在的文件中写入内容。使用removeItemAtPath在导出之前删除了该文件，从而解决了问题。 - David Pettigrew

@DavidPettigrew 感谢您，David！对于2018年使用Swift 4的任何人来说，代码如下：FileManager.default.removeItem(atPath: exportPath)。 - AdjunctProfessorFalcon