In my app, I'm recording small videos and adding them into an NSMutableArray as AVAsset so that i keep record of what has been captured. when the user press a button to merge them, the final result is only the first video taken (example, if three short videos where taken, the final result after merging is only the first video and the others do not appear). my code on iterating in the NSMutableArray and stitching the videos together is here:
if (self.capturedVideos.count != 0) {
//Create AVMutableComposition Object.This object will hold our multiple AVMutableCompositionTrack.
AVMutableComposition* mixComposition = [[AVMutableComposition alloc] init];
for (AVAsset *asset in self.capturedVideos) {
//check if the video is the first one captures so that it is placed at time 0.
if ([self.capturedVideos indexOfObject:asset] == 0) {
AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:kCMTimeZero error:nil];
previousAsset = asset;
} else{
AVMutableCompositionTrack *track = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[track insertTimeRange:CMTimeRangeMake(kCMTimeZero, asset.duration) ofTrack:[[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:previousAsset.duration error:nil];
previousAsset = asset;
}
}
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *myPathDocs = [documentsDirectory stringByAppendingPathComponent:
[NSString stringWithFormat:@"mergeVideo-%d.mov",arc4random() % 1000]];
NSURL *url = [NSURL fileURLWithPath:myPathDocs];
// 5 - Create exporter
AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
exporter.outputURL=url;
exporter.outputFileType = AVFileTypeQuickTimeMovie;
exporter.shouldOptimizeForNetworkUse = YES;
[exporter exportAsynchronouslyWithCompletionHandler:^{
dispatch_async(dispatch_get_main_queue(), ^{
[self exportDidFinish:exporter];
});
}];
}
what's after the for loop is for exporting the video to be saved in camera roll. so where is my mistake? the durations are right (so there is no over lapping). however, i'm doubting in something. There is an instance variable i added after @implementation in braces which is previousAsset which tracks the previous asset added thus knowing where to place the next one. it's of class AVAsset so i didn't initialize it because when i try to it's showing me an error.
previousAsset = [[AVAsset alloc] init];
