From b58d9edc6a536bc6da9ad2718298257b236323f8 Mon Sep 17 00:00:00 2001
From: Vadim Pisarevsky <no@email>
Date: Sat, 21 May 2011 18:07:28 +0000
Subject: [PATCH] return NULL in the case of incorrect camera index (ticket
 #710)

---
 modules/highgui/src/cap_qtkit.mm | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/modules/highgui/src/cap_qtkit.mm b/modules/highgui/src/cap_qtkit.mm
index f88929d750..80b043c817 100644
--- a/modules/highgui/src/cap_qtkit.mm
+++ b/modules/highgui/src/cap_qtkit.mm
@@ -338,11 +338,10 @@ int CvCaptureCAM::startCaptureDevice(int cameraNum) {
 	}
 	
 	if (cameraNum >= 0) {
-		camNum = cameraNum % [devices count]; 
-		if (camNum != cameraNum) {
-			cout << "Warning: Max Camera Num is " << [devices count]-1 << "; Using camera " << camNum << endl; 
-		}
-		device = [devices objectAtIndex:camNum] ;
+		int nCameras = [devices count];
+        if( cameraNum < 0 || cameraNum >= nCameras )
+            return 0;
+		device = [devices objectAtIndex:cameraNum] ;
 	} else {
 		device = [QTCaptureDevice defaultInputDeviceWithMediaType:QTMediaTypeVideo]  ;
 	}