iOS结合三个video – 旋转中心video

我有三个video 第一个来自后置摄像头。 第二个来自前置摄像头，第三个来自后置摄像头。 video总是以横向模式进行拍摄，右边的主页button。

后置video的方向正确。 使用前置摄像头拍摄的中心video以180度旋转（颠倒）。 我一直在研究和尝试许多方法来转换中心video，没有运气。 我每次都得到相同的结果。

我对整个过程感到非常沮丧。 我在网上阅读的所有内容以及评论者在这里的评论/build议应该可以正常工作，但是不起作用。 无论我尝试进行转换，video都是一样的。 它不断地performance得好像我没有应用任何转换。 没有。 我不明白为什么这个转变会被忽略。 我已经花了几个星期了，而且我到了最后 – 这根本行不通。

这是我的代码的当前迭代：

- (void)mergeVideos2:(NSMutableArray *)assets withCompletion:(void (^)(NSString *))completion { AVMutableComposition *mutableComposition = [AVMutableComposition composition]; AVMutableCompositionTrack *videoCompositionTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; __block NSMutableArray *instructions = [[NSMutableArray alloc] init]; __block CGSize size = CGSizeZero; __block CMTime time = kCMTimeZero; __block AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition]; __block CGAffineTransform transformflip = CGAffineTransformMakeScale(1, -1); // __block CGAffineTransform transformflip = CGAffineTransformMakeRotation(M_PI); __block int32_t commontimescale = 600; [assets enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) { NSURL *assetUrl = (NSURL *)obj; AVAsset *asset = [AVAsset assetWithURL:assetUrl]; CMTime cliptime = CMTimeConvertScale(asset.duration, commontimescale, kCMTimeRoundingMethod_QuickTime); NSLog(@"%s: Number of tracks: %lu", __PRETTY_FUNCTION__, (unsigned long)[[asset tracks] count]); AVAssetTrack *assetTrack = [asset tracksWithMediaType:AVMediaTypeVideo].firstObject; NSError *error; [videoCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, cliptime) ofTrack:assetTrack atTime:time error:&error]; if (error) { NSLog(@"%s: Error - %@", __PRETTY_FUNCTION__, error.debugDescription); } AVMutableVideoCompositionLayerInstruction *videoLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoCompositionTrack]; CGAffineTransform transform = assetTrack.preferredTransform; [videoLayerInstruction setTransform:CGAffineTransformConcat(transform, transformflip) atTime:time]; // the main instruction set - this is wrapping the time AVMutableVideoCompositionInstruction *videoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction]; videoCompositionInstruction.timeRange = CMTimeRangeMake(time, assetTrack.timeRange.duration); if (videoLayerInstruction != nil) videoCompositionInstruction.layerInstructions = @[videoLayerInstruction]; [instructions addObject:videoCompositionInstruction]; // time increment variables time = CMTimeAdd(time, cliptime); if (CGSizeEqualToSize(size, CGSizeZero)) { size = assetTrack.naturalSize;; } }]; mutableVideoComposition.instructions = instructions; // set the frame rate to 9fps mutableVideoComposition.frameDuration = CMTimeMake(1, 12); NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths firstObject]; int number = arc4random_uniform(10000); self.outputFile = [documentsDirectory stringByAppendingFormat:@"/export_%i.mov",number]; AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mutableComposition presetName:AVAssetExportPreset1280x720]; exporter.outputURL = [NSURL fileURLWithPath:self.outputFile]; //Set the output file type exporter.outputFileType = AVFileTypeQuickTimeMovie; exporter.shouldOptimizeForNetworkUse = YES; dispatch_group_t group = dispatch_group_create(); dispatch_group_enter(group); [exporter exportAsynchronouslyWithCompletionHandler:^{ dispatch_group_leave(group); }]; dispatch_group_notify(group, dispatch_get_main_queue(), ^{ // get the size of the file unsigned long long size= ([[[NSFileManager defaultManager] attributesOfItemAtPath:self.outputFile error:nil] fileSize]); NSString *filesize = [NSByteCountFormatter stringFromByteCount:size countStyle:NSByteCountFormatterCountStyleFile]; NSString *thereturn = [NSString stringWithFormat:@"%@: %@", self.outputFile, filesize]; NSLog(@"Export File (Final) - %@", self.outputFile); completion(thereturn); }); } 

任何想法或build议？

Answer 1

每个AVAssetTrack都有一个preferredTransform属性。 它包含有关如何旋转和翻译video以正确显示的信息，所以您不必猜测。 在每个图层指令中使用每个video的preferredTransform。

不要设置“videoCompositionTrack.preferredTransform = …”

删除变换斜坡“[videoLayerInstruction setTransformRampFromStartTransform：…”

在这个枚举中，只需使用：

 CGAffineTransform transform = assetTrack.preferredTransform; [videoLayerInstruction setTransform:transform atTime:time]; 

我假设您的video以与您的输出尺寸相同的尺寸进行拍摄，中间video的宽度和高度相反。 如果他们不是，你将不得不添加适当的缩放：

 float scaleFactor = ...// ie (outputWidth / videoWidth) CGAffineTransform scale = CGAffineTransformMakeScale(scaleFactor,scaleFactor) transform = CGAffineTransformConcat(transform, scale); [videoLayerInstruction setTransform:transform atTime:time]; 

编辑 ：它看起来倒过来在构图的源video是颠倒的开始，但有一个身份CGAffineTransform。 这段代码的工作方式正确：

 - (void)mergeVideos2:(NSMutableArray *)assets withCompletion:(void (^)(NSString *))completion { AVMutableComposition *mutableComposition = [AVMutableComposition composition]; AVMutableCompositionTrack *videoCompositionTrack = [mutableComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; __block NSMutableArray *instructions = [[NSMutableArray alloc] init]; __block CMTime time = kCMTimeZero; __block AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition]; __block int32_t commontimescale = 600; // Create one layer instruction. We have one video track, and there should be one layer instruction per video track. AVMutableVideoCompositionLayerInstruction *videoLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoCompositionTrack]; [assets enumerateObjectsUsingBlock:^(id _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) { NSURL *assetUrl = (NSURL *)obj; AVAsset *asset = [AVAsset assetWithURL:assetUrl]; CMTime cliptime = CMTimeConvertScale(asset.duration, commontimescale, kCMTimeRoundingMethod_QuickTime); NSLog(@"%s: Number of tracks: %lu", __PRETTY_FUNCTION__, (unsigned long)[[asset tracks] count]); AVAssetTrack *assetTrack = [asset tracksWithMediaType:AVMediaTypeVideo].firstObject; CGSize naturalSize = assetTrack.naturalSize; NSError *error; //insert the video from the assetTrack into the composition track [videoCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, cliptime) ofTrack:assetTrack atTime:time error:&error]; if (error) { NSLog(@"%s: Error - %@", __PRETTY_FUNCTION__, error.debugDescription); } CGAffineTransform transform = assetTrack.preferredTransform; //set the layer to have this videos transform at the time that this video starts if (<* the video is an intermediate video - has the wrong orientation*>) { //these videos have the identity transform, yet they are upside down. //we need to rotate them by M_PI radians (180 degrees) and shift the video back into place CGAffineTransform rotateTransform = CGAffineTransformMakeRotation(M_PI); CGAffineTransform translateTransform = CGAffineTransformMakeTranslation(naturalSize.width, naturalSize.height); [videoLayerInstruction setTransform:CGAffineTransformConcat(rotateTransform, translateTransform) atTime:time]; } else { [videoLayerInstruction setTransform:transform atTime:time]; } // time increment variables time = CMTimeAdd(time, cliptime); }]; // the main instruction set - this is wrapping the time AVMutableVideoCompositionInstruction *videoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction]; videoCompositionInstruction.timeRange = CMTimeRangeMake(kCMTimeZero,mutableComposition.duration); //make the instruction last for the entire composition videoCompositionInstruction.layerInstructions = @[videoLayerInstruction]; [instructions addObject:videoCompositionInstruction]; mutableVideoComposition.instructions = instructions; // set the frame rate to 9fps mutableVideoComposition.frameDuration = CMTimeMake(1, 12); //set the rendersize for the video we're about to write mutableVideoComposition.renderSize = CGSizeMake(1280,720); NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths firstObject]; int number = arc4random_uniform(10000); self.outputFile = [documentsDirectory stringByAppendingFormat:@"/export_%i.mov",number]; //let the rendersize of the video composition dictate size. use quality preset here AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mutableComposition presetName:AVAssetExportPresetHighestQuality]; exporter.outputURL = [NSURL fileURLWithPath:self.outputFile]; //Set the output file type exporter.outputFileType = AVFileTypeQuickTimeMovie; exporter.shouldOptimizeForNetworkUse = YES; exporter.videoComposition = mutableVideoComposition; dispatch_group_t group = dispatch_group_create(); dispatch_group_enter(group); [exporter exportAsynchronouslyWithCompletionHandler:^{ dispatch_group_leave(group); }]; dispatch_group_notify(group, dispatch_get_main_queue(), ^{ // get the size of the file unsigned long long size= ([[[NSFileManager defaultManager] attributesOfItemAtPath:self.outputFile error:nil] fileSize]); NSString *filesize = [NSByteCountFormatter stringFromByteCount:size countStyle:NSByteCountFormatterCountStyleFile]; NSString *thereturn = [NSString stringWithFormat:@"%@: %@", self.outputFile, filesize]; NSLog(@"Export File (Final) - %@", self.outputFile); completion(thereturn); }); }