{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Convert video to gray scale using OpenCV"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import cv2\n",
    "from IPython.display import HTML\n",
    "from scripts.jupyter.helpers import play_video"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "2018-12-31 12:23:42 URL:http://techslides.com/demos/sample-videos/small.mp4 [383631/383631] -> \"../downloads/small.mp4\" [1]\r\n"
     ]
    }
   ],
   "source": [
    "# Download some sample movie\n",
    "!wget -nc -nv http://techslides.com/demos/sample-videos/small.mp4 -P ../downloads"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "\n",
       "        <video width=\"320\" height=\"240\" controls>\n",
       "        <source src=\"downloads/small.mp4\" type=\"video/mp4\">\n",
       "        Your browser does not support the video tag.\n",
       "        </video>\n",
       "        "
      ],
      "text/plain": [
       "<IPython.core.display.HTML object>"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Let's play it\n",
    "play_video('downloads/small.mp4')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Width=560 Height=320 FPS=30\n"
     ]
    }
   ],
   "source": [
    "# Load the video with OpenCV and check it's properties\n",
    "cap = cv2.VideoCapture('downloads/small.mp4')\n",
    "width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))\n",
    "height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))\n",
    "fps = int(cap.get(cv2.CAP_PROP_FPS))\n",
    "print(\"Width={} Height={} FPS={}\".format(width, height, fps))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Processed 166 frames\n"
     ]
    }
   ],
   "source": [
    "# Convert video to grayscale and save it to file\n",
    "\n",
    "# Seek to first frame in input video\n",
    "cap.set(cv2.CAP_PROP_POS_FRAMES, 0)\n",
    "\n",
    "# Open video writer\n",
    "vid = cv2.VideoWriter('../output/small_bw.mp4',\n",
    "                      cv2.VideoWriter_fourcc(*'H264'),\n",
    "                      fps,\n",
    "                      (width, height),\n",
    "                      isColor=False)\n",
    "\n",
    "# Initialize number of frames counter\n",
    "frames_count = 0\n",
    "\n",
    "while(True):\n",
    "    ret, frame = cap.read()\n",
    "    frames_count += 1 if ret else 0\n",
    "    if ret:\n",
    "        # Convert frame from color to grayscale and write it\n",
    "        frame_bw = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)\n",
    "        vid.write(frame_bw)\n",
    "    else:\n",
    "        vid.release()\n",
    "        break\n",
    "\n",
    "print(\"Processed {} frames\".format(frames_count))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "\n",
       "        <video width=\"320\" height=\"240\" controls>\n",
       "        <source src=\"output/small_bw.mp4\" type=\"video/mp4\">\n",
       "        Your browser does not support the video tag.\n",
       "        </video>\n",
       "        "
      ],
      "text/plain": [
       "<IPython.core.display.HTML object>"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Check the result\n",
    "play_video('output/small_bw.mp4')"
   ]
  }
 ],
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