From fcd877fdc1c56846fc5d609354f52747177255dc Mon Sep 17 00:00:00 2001
From: Jerry <jerry.qiushi@gmail.com>
Date: Thu, 5 Nov 2020 18:09:47 +0800
Subject: [PATCH] fix bug.
 https://github.com/rs/SDAVAssetExportSession/issues/79.

---
 SDAVAssetExportSession.m | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/SDAVAssetExportSession.m b/SDAVAssetExportSession.m
index e99993b..9f53757 100755
--- a/SDAVAssetExportSession.m
+++ b/SDAVAssetExportSession.m
@@ -309,6 +309,13 @@ - (AVMutableVideoComposition *)buildDefaultVideoComposition
 	CGSize targetSize = CGSizeMake([self.videoSettings[AVVideoWidthKey] floatValue], [self.videoSettings[AVVideoHeightKey] floatValue]);
 	CGSize naturalSize = [videoTrack naturalSize];
 	CGAffineTransform transform = videoTrack.preferredTransform;
+    
+    CGRect rect = {{0, 0}, naturalSize};
+    CGRect transformedRect = CGRectApplyAffineTransform(rect, transform);
+    // transformedRect should have origin at 0 if correct; otherwise add offset to correct it
+    transform.tx -= transformedRect.origin.x;
+    transform.ty -= transformedRect.origin.y;
+    
 	// Workaround radar 31928389, see https://github.com/rs/SDAVAssetExportSession/pull/70 for more info
 	if (transform.ty == -560) {
 		transform.ty = 0;