def METHOD_NAME(self):
    r"""
    Return whether command ``ffmpeg`` in the path is functional.
    EXAMPLES::
        sage: from sage.features.ffmpeg import FFmpeg
        sage: FFmpeg().is_functional()   # optional - ffmpeg
        FeatureTestResult('ffmpeg', True)
    """
    # Create the content of 1-pixel png file
    content = b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x00\x01\x00\x00\x00\x01\x08\x00\x00\x00\x00:~\x9bU\x00\x00\x00\nIDATx\x9cc`\x00\x00\x00\x02\x00\x01H\xaf\xa4q\x00\x00\x00\x00IEND\xaeB`\x82'
    # NOTE:
    #
    # This is how the above content of a 1 pixel PNG was created::
    #
    #    sage: import numpy as np
    #    sage: from PIL import Image
    #    sage: image = Image.fromarray(np.array([[100]], dtype=np.uint8))
    #    sage: image.save('file.png')
    #    sage: with open('file.png', 'rb') as f:
    #    ....:     content = f.read()
    # create a png file with the content
    from sage.misc.temporary_file import tmp_filename
    base_filename_png = tmp_filename(ext='.png')
    with open(base_filename_png, 'wb') as f:
        f.write(content)
    # Set up filenames
    import os
    base, filename_png = os.path.split(base_filename_png)
    filename, _png = os.path.splitext(filename_png)
    # Setting a list of commands (taken from sage/plot/animate.py)
    # The `-nostdin` is needed to avoid the command to hang, see
    # https://stackoverflow.com/questions/16523746/ffmpeg-hangs-when-run-in-background
    commands = []
    for ext in ['.avi', '.flv', '.gif', '.mkv', '.mov', #'.mpg',
            '.mp4', '.ogg', '.ogv', '.webm', '.wmv']:
        cmd = ['ffmpeg', '-nostdin', '-y', '-f', 'image2', '-r', '5',
                '-i', filename_png, '-pix_fmt', 'rgb24', '-loop', '0',
                filename + ext]
        commands.append(cmd)
    for ext in ['.avi', '.flv', '.gif', '.mkv', '.mov', '.mpg',
            '.mp4', '.ogg', '.ogv', '.webm', '.wmv']:
        cmd = ['ffmpeg', '-nostdin', '-y', '-f', 'image2', '-i',
                filename_png, filename + ext]
        commands.append(cmd)
    # Running the commands and reporting any issue encountered
    from subprocess import run
    for cmd in commands:
        try:
            result = run(cmd, cwd=base, capture_output=True, text=True)
        except OSError as e:
            return FeatureTestResult(self, False, reason='Running command "{}" '
                        'raised an OSError "{}" '.format(' '.join(cmd), e))
        # If an error occurred, return False
        if result.returncode:
            return FeatureTestResult(self, False, reason='Running command "{}" '
                        'returned non-zero exit status "{}" with stderr '
                        '"{}" and stdout "{}".'.format(result.args,
                                                        result.returncode,
                                                        result.stderr.strip(),
                                                        result.stdout.strip()))
    # If necessary, run more tests here
    # ...
    # The command seems functional
    return FeatureTestResult(self, True)