          """ Extract video to image frames """
          logger.debug("input_: %s, output: %s, fps: %s, extract_ext: '%s', start: %s, duration: %s",
                       input_, output, fps, extract_ext, start, duration)
          _input_opts = Effmpeg._common_ffmpeg_args[:]
          _input = {input_.path: _input_opts}
          _output_opts = '-y -vf fps="' + str(fps) + '" -q:v 1'
          _output_path = output.path + "/" + input_.name + "_%05d" + extract_ext
          _output = {_output_path: _output_opts}
 
</s> remove     def extract(input_=None, output=None, fps=None, extract_ext=None,
 </s> add     def extract(input_=None, output=None, fps=None, extract_ext=None, start=None, duration=None,
        if start is not None and duration is not None:
            _input_opts += '-ss {} -t {}'.format(start, duration)
          """ Extract video to image frames """
          logger.debug("input_: %s, output: %s, fps: %s, extract_ext: '%s', start: %s, duration: %s",
                       input_, output, fps, extract_ext, start, duration)
          _input_opts = Effmpeg._common_ffmpeg_args[:]
        if start is not None and duration is not None:
            _input_opts += '-ss {} -t {}'.format(start, duration)
          _input = {input_.path: _input_opts}
          _output_opts = '-y -vf fps="' + str(fps) + '" -q:v 1'
          _output_path = output.path + "/" + input_.name + "_%05d" + extract_ext
          _output = {_output_path: _output_opts}
keep keep keep add keep keep keep keep
 Fix duration for effmpeg extract 
tools/effmpeg.py