AVAssetExportSession giving me a green border on right and bottom of output video

Question

Here\'s the code:

AVAssetExportSession *exporter = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetHighestQuality];
             


        

Answer 1

This did the magic for me (iOS9, Swift 3, iPhone 6):

Based on: https://www.raywenderlich.com/94404/play-record-merge-videos-ios-swift

Changing mainComposition.renderSize to:

mainComposition.renderSize = CGSize(width: self.mainCompositionWidth, height: self.mainCompositionHeight)

where mainCompositionWidth, mainCompositionHeight are CGFloats and are calculated like this:

 self.mainCompositionWidth = UIScreen.mainScreen().bounds.width
    self.mainCompositionHeight = UIScreen.mainScreen().bounds.height

    while (self.mainCompositionWidth%16>0) { // find the right resolution that can be divided by 16
        self.mainCompositionWidth = self.mainCompositionWidth + 1.0
    }

    while (self.mainCompositionHeight%16>0) { // find the right resolution that can be divided by 16
        self.mainCompositionHeight = self.mainCompositionHeight + 1.0
    }

Also modifying scaleFitRatio in the videoCompositionInstructionForTrack function to:

scaleToFitRatio = self.mainCompositionWidth / assetTrack.naturalSize.height

This made the bottom green line disappear and the video fills the screen.