问不同分辨率的剪辑合并

EN

-(void) mergeClips{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];      
    
    AVMutableCompositionTrack *mutableVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
    
    AVMutableCompositionTrack *mutableAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];

    // loop through the list of videos and add them to the track
    CMTime currentTime = kCMTimeZero;
    
    NSMutableArray* instructionArray = [[NSMutableArray alloc] init];
    if (_clipsArray){
        for (int i = 0; i < (int)[_clipsArray count]; i++){
            NSURL* url = [_clipsArray objectAtIndex:i];
            
            AVAsset *asset = [AVAsset assetWithURL:url];
            
            AVAssetTrack *videoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
            AVAssetTrack *audioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
            
            CGSize size = videoTrack.naturalSize;
            CGFloat widthScale = 1920.0f/size.width;
            CGFloat heightScale = 1080.0f/size.height;
            
// lines that performs resizing
            AVMutableVideoCompositionLayerInstruction *layerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:mutableVideoTrack];
            CGAffineTransform scale = CGAffineTransformMakeScale(widthScale,heightScale);
            CGAffineTransform move = CGAffineTransformMakeTranslation(0,0);
            [layerInstruction setTransform:CGAffineTransformConcat(scale, move) atTime:currentTime];
            [instructionArray addObject:layerInstruction];
            
            
            [mutableVideoTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration)
                                ofTrack:videoTrack
                                 atTime:currentTime error:nil];
            
            [mutableAudioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration)
                                ofTrack:audioTrack
                                 atTime:currentTime error:nil];
            
            currentTime = CMTimeMakeWithSeconds(CMTimeGetSeconds(asset.duration) + CMTimeGetSeconds(currentTime), asset.duration.timescale);
        }
    }
    
    AVMutableVideoCompositionInstruction * mainInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
    
    mainInstruction.timeRange = CMTimeRangeMake(kCMTimeZero, currentTime);
    mainInstruction.layerInstructions = instructionArray;
    
    
    // 4 - Get path
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *lastPostedDayPath = [documentsDirectory stringByAppendingPathComponent:@"lastPostedDay"];
    
    //Check if folder exists, if not create folder
    if (![[NSFileManager defaultManager] fileExistsAtPath:lastPostedDayPath]){
        [[NSFileManager defaultManager] createDirectoryAtPath:lastPostedDayPath withIntermediateDirectories:NO attributes:nil error:nil];
    }
    
    
    NSString *fileName = [NSString stringWithFormat:@"%li_%li_%li.mov", (long)_month, (long)_day, (long)_year];
    
    NSString *finalDayPath = [lastPostedDayPath stringByAppendingPathComponent:fileName];
    
    NSURL *url = [NSURL fileURLWithPath:finalDayPath];
    
    BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:finalDayPath];
    if (fileExists){
        NSLog(@"file exists");
        [[NSFileManager defaultManager] removeItemAtURL:url error:nil];
    }
    
    AVMutableVideoComposition *mainComposition = [AVMutableVideoComposition videoComposition];
    
    mainComposition.instructions = [NSArray arrayWithObject:mainInstruction];
    mainComposition.frameDuration = CMTimeMake(1, 30);
    mainComposition.renderSize = CGSizeMake(1920.0f, 1080.0f);
    
    // 5 - Create exporter
    _exportSession = [[AVAssetExportSession alloc] initWithAsset:mixComposition
                                                                            presetName:AVAssetExportPresetHighestQuality];
    _exportSession.outputURL=url;
    _exportSession.outputFileType = AVFileTypeQuickTimeMovie;
    _exportSession.shouldOptimizeForNetworkUse = YES;
    _exportSession.videoComposition = mainComposition;
    
    [_exportSession exportAsynchronouslyWithCompletionHandler:^{
        [merge_timer invalidate];
        merge_timer = nil;
        
        switch (_exportSession.status) {
            case AVAssetExportSessionStatusFailed:
                NSLog(@"Export failed -> Reason: %@, User Info: %@",
                      _exportSession.error.localizedDescription,
                      _exportSession.error.userInfo.description);
                [self showSavingFailedDialog];
                break;
                
            case AVAssetExportSessionStatusCancelled:
                NSLog(@"Export cancelled");
                [self showSavingFailedDialog];
                
                break;
                
            case AVAssetExportSessionStatusCompleted:
                NSLog(@"Export finished");
                [self addWatermarkToExportSession:_exportSession];
                
                break;
                
            default:
                break;
        }
    }];
});
}