Grid

mg_grid

mg_grid(self, height=300, rows=3, columns=3, padding=0, margin=0, target_name=None, overwrite=True, return_array=False)

Generates frame strip video preview using ffmpeg.

Parameters:

Name	Type	Description	Default
height	int	Frame height, width is adjusted automatically to keep the correct aspect ratio. Defaults to 300.	300
rows	int	Number of rows of the grid. Defaults to 3.	3
columns	int	Number of columns of the grid. Defaults to 3.	3
padding	int	Padding size between the frames. Defaults to 0.	0
margin	int	Margin size for the grid. Defaults to 0.	0
target_name	[type]	Target output name for the grid image. Defaults to None.	None
overwrite	bool	Whether to allow overwriting existing files or to automatically increment target filenames to avoid overwriting. Defaults to True.	True
return_array	bool	Whether to return an array of not. If set to False the function writes the grid image to disk. Defaults to False.	False

Returns:

Name	Type	Description
MgImage		An MgImage object referring to the internal grid image.

Source code in musicalgestures/_grid.py

def mg_grid(self, height=300, rows=3, columns=3, padding=0, margin=0, target_name=None, overwrite=True, return_array=False):
    """
    Generates frame strip video preview using ffmpeg.

    Args:
        height (int, optional): Frame height, width is adjusted automatically to keep the correct aspect ratio. Defaults to 300.
        rows (int, optional): Number of rows of the grid. Defaults to 3.
        columns (int, optional): Number of columns of the grid. Defaults to 3.
        padding (int, optional): Padding size between the frames. Defaults to 0.
        margin (int, optional): Margin size for the grid. Defaults to 0.
        target_name ([type], optional): Target output name for the grid image. Defaults to None.
        overwrite (bool, optional): Whether to allow overwriting existing files or to automatically increment target filenames to avoid overwriting. Defaults to True.
        return_array (bool, optional): Whether to return an array of not. If set to False the function writes the grid image to disk. Defaults to False.

    Returns:
        MgImage: An MgImage object referring to the internal grid image.
    """

    of, fex = os.path.splitext(self.filename)
    target_name = resolve_filename(of, '_grid.png', target_name, overwrite)

    # Get the number of frames
    cap = cv2.VideoCapture(self.filename)
    nb_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
    nth_frame = int(nb_frames / (rows*columns))

    # Define the grid specifications
    width = int((float(self.width) / self.height) * height)
    grid = rf"select=not(mod(n\,{nth_frame})),scale={width}:{height},tile={columns}x{rows}:padding={padding}:margin={margin}"

    # Declare the ffmpeg commands
    if return_array:
        cmd = ['ffmpeg', '-y', '-i', self.filename, '-frames', '1', '-q:v', '0', '-vf', grid]
        process = ffmpeg_cmd(cmd, get_length(self.filename), pb_prefix='Rendering video frame grid:', pipe='load')

        # Convert bytes to array and convert from BGR to RGB
        array = np.frombuffer(process.stdout, dtype=np.uint8).reshape([height*rows, int(width*columns), 3])[...,::-1] 

        return array
    else:
        cmd = ['ffmpeg', '-i', self.filename, '-y', '-frames', '1', '-q:v', '0', '-vf', grid, target_name]
        ffmpeg_cmd(cmd, get_length(self.filename), pb_prefix='Rendering video frame grid:')
        # Initialize the MgImage object
        img = MgImage(target_name)

        return img