come controllare l'orientamento del video assemblato con AVMutableComposition

Question

Sto assemblando un gruppo di videoclip filmati su iPhone in modalità verticale. Per assemblare li sto prendendo approccio diretto come segue:

AVURLAsset per entrare in possesso dei diversi video poi spintoni questi in un AVMutableCompositionTrack e poi mettere questo in un AVMutableComposition quale sto esportazione di file con AVAssetExportSession

mio il problema è che quando vengo a visualizzare il video in una UIWebView, appare in modalità orizzontale. Tuttavia, se visualizzo una delle viste componente che compaiono in vista verticale. Qualcuno sa come risolvere l'orientamento. Ho provato a fare confusione con AVMutableComposition naturalSize, modificando la larghezza e l'altezza, ma questo ha fatto sembrare la mia gente corta e grassa! (Mentre dalla loro parte)

Grazie in anticipo per eventuali pensieri/suggerimenti

Tudor

Answer 1

Setup una composizione video che gestirà ruotare + scala:

AVMutableVideoComposition* videoComposition = [[AVMutableVideoComposition videoComposition]retain]; 
videoComposition.renderSize = CGSizeMake(320, 240); 
videoComposition.frameDuration = CMTimeMake(1, 30); 

AVMutableVideoCompositionInstruction *instruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction]; 
instruction.timeRange = CMTimeRangeMake(kCMTimeZero, CMTimeMakeWithSeconds(60, 30)); 

AVMutableVideoCompositionLayerInstruction* rotator = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]]; 
CGAffineTransform translateToCenter = CGAffineTransformMakeTranslation(0,-320);  
CGAffineTransform rotateBy90Degrees = CGAffineTransformMakeRotation(M_PI_2); 
CGAffineTransform shrinkWidth = CGAffineTransformMakeScale(0.66, 1); // needed because Apple does a "stretch" by default - really, we should find and undo apple's stretch - I suspect it'll be a CALayer defaultTransform, or UIView property causing this 
CGAffineTransform finalTransform = CGAffineTransformConcat(shrinkWidth, CGAffineTransformConcat(translateToCenter, rotateBy90Degrees)); 
[rotator setTransform:finalTransform atTime:kCMTimeZero]; 

instruction.layerInstructions = [NSArray arrayWithObject: rotator]; 
videoComposition.instructions = [NSArray arrayWithObject: instruction]; 

Answer 2

Ecco un po 'di codice che regolata la rotazione utilizzando la trasformazione preferita:

// our composition, with one video and one audio track 
AVMutableComposition* composition = [AVMutableComposition composition]; 
AVMutableCompositionTrack *videoTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; 
AVMutableCompositionTrack *audioTrack = [composition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid]; 

// loop through all the clips, adding them to our track and inserting composition instructions 
NSDictionary* options = @{ AVURLAssetPreferPreciseDurationAndTimingKey: @YES }; 
CMTime insertionPoint = kCMTimeZero; 
NSMutableArray* instructions = [NSMutableArray array]; 
NSError* error = nil; 
for (NSURL* outputFileURL in self.movieFileURLs) { 
    AVURLAsset *asset = [AVURLAsset URLAssetWithURL:outputFileURL options:options]; 

    // insert this clip's video track into our composition 
    NSArray *videoAssetTracks = [asset tracksWithMediaType:AVMediaTypeVideo]; 
    AVAssetTrack *videoAssetTrack = (videoAssetTracks.count > 0 ? [videoAssetTracks objectAtIndex:0] : nil); 
    [videoTrack insertTimeRange:CMTimeRangeFromTimeToTime(kCMTimeZero, asset.duration) ofTrack:videoAssetTrack atTime:insertionPoint error:&error]; 

    // create a layer instruction at the start of this clip to apply the preferred transform to correct orientation issues 
    AVMutableVideoCompositionLayerInstruction *instruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:videoAssetTrack]; 
    [instruction setTransform:videoAssetTrack.preferredTransform atTime:kCMTimeZero]; 

    // create the composition instructions for the range of this clip 
    AVMutableVideoCompositionInstruction * videoTrackInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction]; 
    videoTrackInstruction.timeRange = CMTimeRangeMake(insertionPoint, asset.duration); 
    videoTrackInstruction.layerInstructions = @[instruction]; 
    [instructions addObject:videoTrackInstruction]; 

    // insert this clip's audio track into our composition 
    NSArray *audioAssetTracks = [asset tracksWithMediaType:AVMediaTypeAudio]; 
    AVAssetTrack *audioAssetTrack = (audioAssetTracks.count > 0 ? [audioAssetTracks objectAtIndex:0] : nil); 
    [audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:audioAssetTrack atTime:insertionPoint error:nil]; 

    // advance the insertion point to the end of the clip 
    insertionPoint = CMTimeAdd(insertionPoint, asset.duration); 
} 

// create our video composition which will be assigned to the player item 
AVMutableVideoComposition *videoComposition = [AVMutableVideoComposition videoComposition]; 
videoComposition.instructions = instructions; 
videoComposition.frameDuration = CMTimeMake(1, videoTrack.naturalTimeScale); 
videoComposition.renderSize = videoTrack.naturalSize; 
_videoComposition = videoComposition; 

Answer 3

Se tutto che vogliamo è preservare voi orientamento il video si può decidere di assegnare il valore AVMutableCompositionTrack prefferedTransition da AVAssetTrack come questo:

AVAssetTrack *videoAssetTrack= [[videoAsset tracksWithMediaType:AVMediaTypeVideo] lastObject]; 

AVMutableCompositionTrack *videoCompositionTrack = [composition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid]; 
[videoCompositionTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, videoAsset.duration) ofTrack:videoAssetTrack atTime:kCMTimeZero error:&error]; 

videoCompositionTrack.preferredTransform = videoAssetTrack.preferredTransform;