修剪视频而不显示UIVideoEditorController？

Question

目前，我正在开发一个处理视频的应用程序。在我的应用程序中，用户可以修剪视频，我有一个自定义控件来选择开始时间和结束时间。我需要用这两个值来修剪视频。我试过使用UIVideoEditorController，如下所示。

    UIVideoEditorController* videoEditor = [[[UIVideoEditorController alloc] init] autorelease];
    videoEditor.delegate = self;
    NSString* videoPath = [[NSBundle mainBundle] pathForResource:@"test" ofType:@"MOV"];
    if ( [UIVideoEditorController canEditVideoAtPath:videoPath] )
    {
      videoEditor.videoPath = videoPath;
      [self presentModalViewController:videoEditor animated:YES];
    }
    else
    {
      NSLog( @"can't edit video at %@", videoPath );
    }

但问题是上面的代码会显示苹果的视频编辑器控件，用户可以在这个视图上做一些操作。我不想显示这个视图，因为我已经在MPMoviePlayer上显示了视频，并收到了用户输入(start time和end time)，用于在自定义控件上微调视频。如何在不显示UIVideoEditorController的情况下修剪视频？

Answer 1

最后我找到了解决办法。

我们可以使用AVAssetExportSession对视频进行裁剪，而无需显示UIVideoEditorController。

我的代码是：

- (void)splitVideo:(NSString *)outputURL
{

    @try
    {
        NSString *videoBundleURL = [[NSBundle mainBundle] pathForResource:@"Video_Album" ofType:@"mp4"];

        AVAsset *asset = [[AVURLAsset alloc] initWithURL:[NSURL fileURLWithPath:videoBundleURL] options:nil];

        NSArray *compatiblePresets = [AVAssetExportSession exportPresetsCompatibleWithAsset:asset];

        if ([compatiblePresets containsObject:AVAssetExportPresetLowQuality])
        {

            [self trimVideo:outputURL assetObject:asset];

        }
        videoBundleURL = nil;

        [asset release];
        asset = nil;

        compatiblePresets = nil;
    }
    @catch (NSException * e)
    {
        NSLog(@"Exception Name:%@ Reason:%@",[e name],[e reason]);
    }
}

该方法对视频进行裁剪。

- (void)trimVideo:(NSString *)outputURL assetObject:(AVAsset *)asset
  {

    @try
    {

        AVAssetExportSession *exportSession = [[AVAssetExportSession alloc]initWithAsset:asset presetName:AVAssetExportPresetLowQuality];

        exportSession.outputURL = [NSURL fileURLWithPath:outputURL];

        exportSession.outputFileType = AVFileTypeQuickTimeMovie;

        CMTime start = CMTimeMakeWithSeconds(splitedDetails.startTime, 1);

        CMTime duration = CMTimeMakeWithSeconds((splitedDetails.stopTime - splitedDetails.startTime), 1);

        CMTimeRange range = CMTimeRangeMake(start, duration);

        exportSession.timeRange = range;

        exportSession.outputFileType = AVFileTypeQuickTimeMovie;

        [self checkExportSessionStatus:exportSession];

        [exportSession release];
        exportSession = nil;

    }
    @catch (NSException * e)
    {
        NSLog(@"Exception Name:%@ Reason:%@",[e name],[e reason]);
    }
}

此方法检查修整的状态：

- (void)checkExportSessionStatus:(AVAssetExportSession *)exportSession
  {

    [exportSession exportAsynchronouslyWithCompletionHandler:^(void)
    {

        switch ([exportSession status])
            {

            case AVAssetExportSessionStatusCompleted:

                NSLog(@"Export Completed");
                break;

            case AVAssetExportSessionStatusFailed:

                NSLog(@"Error in exporting");
                break;

            default:
                break;

        }
    }];
}

我从导出按钮操作方法调用splitVideo方法，并将输出URL作为参数传递。

Answer 2

我们可以进口AVFoundation/AVFound.h

-(BOOL)trimVideofile
{

    float videoStartTime;//define start time of video
    float videoEndTime;//define end time of video
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd_HH-mm-ss"];
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory, NSUserDomainMask, YES);
    NSString *libraryCachesDirectory = [paths objectAtIndex:0];
    libraryCachesDirectory = [libraryCachesDirectory stringByAppendingPathComponent:@"Caches"];
    NSString *OutputFilePath = [libraryCachesDirectory stringByAppendingFormat:@"/output_%@.mov", [dateFormatter stringFromDate:[NSDate date]]];
    NSURL *videoFileOutput = [NSURL fileURLWithPath:OutputFilePath];
    NSURL *videoFileInput;//<Path of orignal Video file>

    if (!videoFileInput || !videoFileOutput)
    {
        return NO;
    }

    [[NSFileManager defaultManager] removeItemAtURL:videoFileOutput error:NULL];
    AVAsset *asset = [AVAsset assetWithURL:videoFileInput];

    AVAssetExportSession *exportSession = [AVAssetExportSession exportSessionWithAsset:asset
                                                                            presetName:AVAssetExportPresetLowQuality];
    if (exportSession == nil)
    {
        return NO;
    }
    CMTime startTime = CMTimeMake((int)(floor(videoStartTime * 100)), 100);
    CMTime stopTime = CMTimeMake((int)(ceil(videoEndTime * 100)), 100);
    CMTimeRange exportTimeRange = CMTimeRangeFromTimeToTime(startTime, stopTime);

    exportSession.outputURL = videoFileOutput;
    exportSession.timeRange = exportTimeRange;
    exportSession.outputFileType = AVFileTypeQuickTimeMovie;

    [exportSession exportAsynchronouslyWithCompletionHandler:^
     {
         if (AVAssetExportSessionStatusCompleted == exportSession.status)
         {
            NSLog(@"Export OK");
         }
         else if (AVAssetExportSessionStatusFailed == exportSession.status)
         {
             NSLog(@"Export failed: %@", [[exportSession error] localizedDescription]);
         }
     }];
    return YES;
}