Arbitrary font type with ffmpeg

I set up a script that generates a simple video with one mp3 audio and one text on screen. I would like to add the option to specify a font type and use that for formatting of the text on the video.

This is my code:

import subprocessfrom pathlib import Pathfrom myproject import AUDIOS_FOLDER, FONTS_FOLDERfont_name = "Montserrat-LightItalic"font_path = str(FONTS_FOLDER / font_name) +'.ttf'assert Path(font_path).is_file()ffmpeg_command = ['ffmpeg','-y','-f', 'lavfi','-i', 'color=c=gray:s=640x480:d=4','-i', f'{str(AUDIOS_FOLDER / "i_have_a_cat.mp3")}','-vf', f'drawtext=text=\'I have a cat\':fontsize=24:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2:fontfile=\'{font_path}\'',    str(ffmpeg_poc_path / 'output.mp4')]subprocess.run(ffmpeg_command)

The problem I am facing is that the :fontfile=\'{font_path}\' setting doesn't get activated. The above code produces the exact same output as if I drop the :fontfile=\'{font_path}\' section entirely.

I tried using alternative font names without using the font_path, e.g.:

'-vf', f'drawtext=text=\'I have a cat\':fontsize=24:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2:fontfile=\'arialbd.ttf\''

or

'-vf', f'drawtext=text=\'I have a cat\':fontsize=24:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2:fontfile=\'sseriff.ttf\''

but these didn't work either, despite both files existing at C:\Windows\Fonts on my local device. So at this stage, I concluded that neither the system default fonts, nor the custom installed, project-specific ones work.

Note 1: I also tried with and without single and double quotes, with no success:

:fontfile='sseriff.ttf':fontfile=\'sseriff.ttf\':fontfile="sseriff.ttf":fontfile=\"sseriff.ttf\"

Note 2: As for the project-specific fonts which I intend to collect under: project_root/fonts directory, I came across this comment and I transformed the path as advised here; with no success:

font_path = font_path.replace("\\", "\\\\").replace("C:", "C\:")# example result: C\:\\user\\OneDrive\\Desktop\\myproject\\fonts\\Montserrat-LightItalic.ttf

Note 3: Based on Rotem's advice below, I copied the custom font files from C:\Windows\Fonts to my working directory. In the below case, I used the arialbd.ttf custom font:

'-vf', f'drawtext=text=\'I have a cat\':fontsize=24:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2:fontfile=arialbd.ttf'

Note that no quotes should be used around the filename; otherwise, the font won't be applied.

While this works perfectly, I am still unable to reference an arbitrary font type via an absolute path. The following approach doesn't work:

font_path = FONTS_FOLDER / "arialbd.ttf"assert font_path.is_file()font_path_str = str(font_path)# path looks like this: c:\user\OneDrive\myproject\fonts\arialbd.ttfffmpeg_command = ['ffmpeg','-y','-f', 'lavfi','-i', 'color=c=gray:s=640x480:d=4','-i', f'{str(audios_path / "i_have_a_cat.mp3")}','-vf', f'drawtext=text=\'I have a cat\':fontsize=24:fontcolor=white:x=(w-text_w)/2:y=(h-text_h)/2:fontfile={font_path_str}',    str(ffmpeg_poc_path / 'output.mp4')]

I also tried to duplicate all backslashes and convert C:\ to C\:\ but still no success.