when encrypt the video by HM 16.9,An error occurred.
I encrypt the merge index by encoder.the code are as follow
Void TEncSbac::codeMergeIndex( TComDataCU* pcCU, UInt uiAbsPartIdx )
{

UInt uiUnaryIdx = pcCU->getMergeIndex( uiAbsPartIdx );
Int Key_Mergeidx=0;
for(int i = 0;i< 2;i++)

{

if(num4 >7999) num4 = 0;
if(keyArr[num4++])
Key_Mergeidx+=1<<(2-i-1);

}
uiUnaryIdx=(uiUnaryIdx+Key_Mergeidx)%5;

and then I decrypt it by decoder via the codes below

Int Key_Mergeidx=0;

for(int i = 0;i< 2;i++)
{

if(num4 >7999) num4 = 0;
if(keyArr[num4++])

Key_Mergeidx+=1<<(2-i-1);

}
uiUnaryIdx=(uiUnaryIdx+5-Key_Mergeidx)%5;

the yuv sequence I get is a little different from the version which just encode and then decode. Actually I just change the merge index to a number between 0 and 4 at encoder,and it is reversible, but after decode and decrypt, in some frames, a little pixels are not the same as the version which just encode and then decode.can you tell why? thank you very much!,it is definitely important for me to solve this problem.