OpenCv image unstable while running AES decryption - opencv

Question

I am trying to capture video from webcam using Opencv and transmit it over TCP. In addition, I wanted to encrypt the video using AES. But whenever run the AES decrpt function the video is unstable.
I am using the opencv over tcp example and AES example
Whenever I run this function:
img->imageData = aes_decrypt(&de, img->imageData, &imgsize);
my video gets unstable.
I have attached the code segment where I wrote the function.
/* start receiving images*/
while(1)
{
/* get raw data */
for (i = 0; i < imgsize; i += bytes) {
if ((bytes = recv(sock, sockdata + i, imgsize - i, 0)) == -1) {
quit("recv failed", 1);
}
}
pthread_mutex_lock(&mutex);
for (i = 0, k = 0; i < img->height; i++) {
for (j = 0; j < img->width; j++) {
((uchar*)(img->imageData + i * img->widthStep))[j] = sockdata[k++];
}
}
img->imageData = aes_decrypt(&de, img->imageData, &imgsize);
is_data_ready = 1;
pthread_mutex_unlock(&mutex);
/* have we terminated yet? */
pthread_testcancel();
/* no, take a rest for a while */
usleep(1000);
}
This is my first post, sorry for my bad English and format of the post.