我有一组视频片段，我想将它们合并在一起，然后在上面放上水印。
我可以单独执行这两个功能，但是同时执行它们会出现问题。
将要合并的所有剪辑均为1920x1080或960x540。
由于某些原因，AVASsetExportSession无法将它们很好地显示在一起。
以下是基于3种不同情况的2个错误:
该图像是以下结果的结果:
如您所见，这里没有错，输出视频产生了预期的效果。
但是，当我尝试添加水印时，它会产生以下问题:
该图像是以下结果的结果:
错误1:出于某些原因，视频中的某些剪辑会调整大小，而其他剪辑则不会。
该图像是以下结果的结果:
错误2 现在，需要重新调整大小的剪辑已重新调整大小，但是旧的未调整大小的剪辑仍然存在。
合并/调整大小代码:
-(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;
}
}];
});
}
我的代码或过程中有什么地方做错了吗？
有没有更简单的方法可以实现这一目标？
感谢您的时间!
最佳答案
我能够解决我的问题。
由于某些原因，AVASsetExportSession实际上不会为合并的剪辑创建一个“平坦”的视频文件，因此在添加水印导致其调整大小时，它仍能识别较低分辨率的剪辑及其位置。
我要做的是，首先使用AVAssetWriter合并我的剪辑并创建一个“平面”文件。然后，我可以添加水印而不会出现大小调整问题。
希望这对将来可能遇到此问题的任何人有所帮助!
关于ios - 合并具有不同分辨率的剪辑，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/31363396/