class_docstr: Video output implemented by streaming to FFmpeg with .mp4 output.
class_docstr_tok: ["Video","output","implemented","by","streaming","to","FFmpeg","with",".mp4","output","."]
code: def emit_frame(self, np_array):
      try:
          self.ffmpeg.stdin.write(np_array.tobytes())
          self.ffmpeg.stdin.flush()
      except IOError:
          self._handle_error()
          raise IOError("Failure invoking FFmpeg")
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import abc
  import os
  import subprocess
  import time
  import numpy
label_desc: Use image node_id 4 for calling the FFmpegVideoOutput obj's underlying member method code with example usage: obj.emit_frame(np_array) without return types