def get_frame_filename_template(frame_end, filename_prefix=None, ext=None):
    """Get file template with frame key for rendered files.

    This is simple template contains `{frame}{ext}` for sequential outputs
    and `single_file{ext}` for single file output. Output is rendered to
    temporary folder so filename should not matter as integrator change
    them.
    """
    frame_padding = 4
    frame_end_str_len = len(str(frame_end))
    if frame_end_str_len > frame_padding:
        frame_padding = frame_end_str_len

    ext = ext or ".png"
    filename_prefix = filename_prefix or ""

    return "{}{{frame:0>{}}}{}".format(filename_prefix, frame_padding, ext)