Ответ 1
Да, возможно объединить 2 видео:
1. Добавьте оба актива в AVMutableComposition во время запуска 0.
2. Установите предпочтительное преобразование в дорожки в этом примере масштабирования.
- (void) mergeVideos{
///... after getting hold or your assets....firstAsset, secondAsset
AVMutableComposition* mixComposition = [AVMutableComposition composition];
AVMutableCompositionTrack *firstTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTracfirst:kCMPersistentTracfirst_Invalid];
[firstTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, firstAsset.duration)
ofTrack:[[firstAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
atTime:kCMTimeZero error:nil];
AVMutableCompositionTrack *secondTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo
preferredTracfirst:kCMPersistentTracfirst_Invalid];
[secondTrack insertTimeRange:CMTimeRangeMake(kCMTimeZero, secondAsset.duration)
ofTrack:[[secondAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0]
atTime:kCMTimeZero error:nil];
[secondTrack setPreferredTransform:CGAffineTransformMakeScale(0.25f,0.25f)];
//... export video here...
}