Video Could Not Be Composed when using AVAssetExportPresetHighestQuality - ios

Question

I am tying to create an app that splices together a number of videos. The issue seems to be that when I combine instructions with AVAssetExportPresetHighestQuality I get an error stating that
Export failed -> Reason: The video could not be composed., User Info:
{
NSLocalizedDescription = "Operation Stopped";
NSLocalizedFailureReason = "The video could not be composed.";
NSUnderlyingError = "Error Domain=NSOSStatusErrorDomain Code=-17390 \"(null)\""; }
If I change it to AVAssetExportPresetPassthrough it works ok but the instructions are ignored. Does anyone know what the issue might be using the following code. Im nearly there but this issue is holding me up.
AVMutableComposition *mixComposition = [[AVMutableComposition alloc] init];
AVMutableCompositionTrack *track = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTrackID:kCMPersistentTrackID_Invalid];
AVMutableCompositionTrack *audioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio
preferredTrackID:kCMPersistentTrackID_Invalid];
CMTime insertTime = kCMTimeZero;
NSMutableArray *arrayInstructions = [[NSMutableArray alloc] init];
int i = 0;
for (NSMutableDictionary * dict in self.arraySelectedAssets) {
AVAsset *asset = [dict objectForKey:#"avasset"];
//[self orientationForTrack:asset];
AVAssetTrack* videoAssetTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
AVAssetTrack* audioAssetTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0];
[track insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:videoAssetTrack atTime:insertTime error:nil];
[audioTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:audioAssetTrack atTime:insertTime error:nil];
AVMutableVideoCompositionInstruction *firstVideoCompositionInstruction = [AVMutableVideoCompositionInstruction videoCompositionInstruction];
// Set the time range of the first instruction to span the duration of the first video track.
firstVideoCompositionInstruction.timeRange = CMTimeRangeMake(insertTime, videoAssetTrack.timeRange.duration);
AVMutableVideoCompositionLayerInstruction* firstVideoLayerInstruction = [AVMutableVideoCompositionLayerInstruction videoCompositionLayerInstructionWithAssetTrack:[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]];
CGAffineTransform translateToCenter = CGAffineTransformMakeTranslation( 0,-1334);
CGAffineTransform rotateBy90Degrees = CGAffineTransformMakeRotation( M_PI_2);
CGAffineTransform shrinkWidth = CGAffineTransformMakeScale(0.1, 0.1); // 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) );
[firstVideoLayerInstruction setTransform:finalTransform atTime:kCMTimeZero];
firstVideoCompositionInstruction.layerInstructions = #[firstVideoLayerInstruction];
[arrayInstructions addObject:firstVideoCompositionInstruction];
insertTime = CMTimeAdd(insertTime, videoAssetTrack.timeRange.duration);
i = i + 1;
}
AVMutableVideoComposition *mutableVideoComposition = [AVMutableVideoComposition videoComposition];
mutableVideoComposition.instructions = arrayInstructions;
mutableVideoComposition.renderSize = CGSizeMake(1334, 750);
mutableVideoComposition.frameDuration = CMTimeMake(1, 30);
// 4 - Get path
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *myPathDocs = [documentsDirectory stringByAppendingPathComponent:
[NSString stringWithFormat:#"mergeVideo-%d.mov",arc4random() % 1000]];
self.combinedVideoURL = [NSURL fileURLWithPath:myPathDocs];
// 5 - Create exporter
self.timerExporter = [NSTimer scheduledTimerWithTimeInterval:0.01f
target:self
selector:#selector(exporterProgress)
userInfo:nil
repeats:YES];
// 5 - Create exporter
self.exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition
presetName:AVAssetExportPresetHighestQuality];
self.exporter .outputURL=self.combinedVideoURL;
self.exporter .outputFileType = AVFileTypeQuickTimeMovie;
self.exporter .shouldOptimizeForNetworkUse = YES;
self.exporter.videoComposition = mutableVideoComposition;
[self.exporter exportAsynchronouslyWithCompletionHandler:^{
[self.timerExporter invalidate];
switch (self.exporter.status) {
case AVAssetExportSessionStatusFailed:
NSLog(#"Export failed -> Reason: %#, User Info: %#",
self.exporter.error.localizedFailureReason,
self.exporter.error.userInfo.description);
[self showError:self.exporter.error.localizedFailureReason];
break;
case AVAssetExportSessionStatusCancelled:
NSLog(#"Export cancelled");
break;
case AVAssetExportSessionStatusCompleted:
NSLog(#"Export finished");
dispatch_async(dispatch_get_main_queue(), ^{
self.labelProgressText.text = [NSString stringWithFormat:#"%# (100%%)", NSLocalizedString(#"Combining The Videos", nil)];
[self applyTheFilter];
});
break;
}
}];

Answer 1

This is not the answer you're looking for, I'm afraid. I had the same problem transforming and exporting a single video - AVAssetExportPresetHighestQuality would work for some assets and not for others.
My guess at the time was that the assets that didn't work weren't of a high enough size/framerate/quality to render using AVAssetExportPresetHighestQuality.
As you did, I ended up using AVAssetExportPresetPassthrough. In your case the end result will presumably be that all the assets you're splicing together will be rendered in their original format.