title: Encoding HEVC video using OpenCV and ffmpeg backend
body: <p>I try to encode my webcam using OpenCV with ffmpeg backend and Python3 to an HEVC video.
  It works fine with other codecs like <code>mjpg</code>. 
  Here is my example script which uses the corresponding <a href="http://www.fourcc.org/hevc/" rel="nofollow noreferrer">fourcc</a> (also tried <code>hevc</code>, <code>h265</code>, <code>x265</code>, etc.):</p>
  
  <pre><code>#!/bin/python3
  
  import cv2
  import time
  import subprocess
  
  def video(seconds, frameRate):
      cap = cv2.VideoCapture(0)
      if(not cap.isOpened()):
          return "error"
  
      # Define the codec and create VideoWriter object
      fourcc = cv2.VideoWriter_fourcc(*'HEVC')
      name = "/tmp/" + time.strftime("%d-%m-%Y_%X")+".hevc"
      out = cv2.VideoWriter(name, fourcc, frameRate, (640,480))
      program_starts = time.time()
      result = subprocess.Popen(["ffprobe", name], stdout = subprocess.PIPE, stderr = subprocess.STDOUT, shell=True)
      nFrames=0
      while(nFrames&lt;seconds*frameRate):
          ret, frame = cap.read()
          if ret==True:
              out.write(frame)
              nFrames += 1
          else:
              break
      cap.release()
      return name 
  # Store a video to /tmp for 2 seconds
  print(video(2,15))
  </code></pre>
  
  <p><strong>Returning error:</strong></p>
  
  <pre><code>OpenCV: FFMPEG: tag 0x43564548/'HEVC' is not found (format 'hevc / raw HEVC video')'
  </code></pre>
  
  <p><strong>My Ubuntu system configuration is as follows:</strong></p>
  
  <pre><code>bash&gt; cat /etc/issue
  Ubuntu 16.04.6 LTS \n \l
  </code></pre>
  
  <pre><code>bash&gt; python3 -m pip list | grep opencv
  opencv-contrib-python-nonfree 4.1.1.1               
  opencv-python-nonfree         4.1.1.1
  </code></pre>
  
  <pre><code>bash&gt; ffmpeg -encoders
  ffmpeg version 2.8.15-0ubuntu0.16.04.1 Copyright (c) 2000-2018 the FFmpeg developers
    built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.10) 20160609
    configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
    libavutil      54. 31.100 / 54. 31.100
    libavcodec     56. 60.100 / 56. 60.100
    libavformat    56. 40.101 / 56. 40.101
    libavdevice    56.  4.100 / 56.  4.100
    libavfilter     5. 40.101 /  5. 40.101
    libavresample   2.  1.  0 /  2.  1.  0
    libswscale      3.  1.101 /  3.  1.101
    libswresample   1.  2.101 /  1.  2.101
    libpostproc    53.  3.100 / 53.  3.100
  Encoders:
  ...
   V..... libx265              libx265 H.265 / HEVC (codec hevc)
  ...
  </code></pre>