FAQ & Troubleshooting¶

Frequently asked questions and common issues.

General Questions¶

Where is the output video saved?¶

After calling render(), the final MP4 is placed next to Manim’s internal render output, using the name you provided via video_name:

./media/videos/1080p60/{video_name}.mp4

The exact sub-directory (e.g. 1080p60) depends on Manim’s current quality configuration.

Cairo vs. OpenGL – which should I use?¶

Cairo (default, renderer='cairo') – CPU-based, works on virtually all systems.
OpenGL (renderer='opengl') – GPU-based, can be faster but requires compatible graphics drivers.

If you encounter rendering errors with OpenGL, switch back to Cairo:

video = CameraFollowCursorCV(
    code=('string', 'code'),
    language='python',
    renderer='cairo'
)

Does it support Chinese characters?¶

Yes. CodeVideoRenderer bundles CodeVideoRendererFont to support CJK characters. If you see garbled text, ensure your input code is valid UTF-8.

Common Issues¶

FFmpeg not found¶

If rendering fails with an FFmpeg-related error, verify FFmpeg is installed and available in your PATH:

ffmpeg -version

If the command is not found, reinstall FFmpeg (see Installation) and restart your terminal.

Invalid characters error¶

CodeVideoRenderer rejects the following characters because they can break Manim’s text layout:

\r (carriage return)
\v (vertical tab)
\f (form feed)

If your code contains these (often copied from certain editors), replace them with regular spaces or newlines before passing the string to CameraFollowCursorCV.

Code is cut off or too large¶

If your code block overflows the visible area or the camera zoom feels wrong, adjust camera_scale:

# Zoom out for large files
video = CameraFollowCursorCV(
    code=('file', 'large_script.py'),
    language='python',
    camera_scale=0.3
)

Values smaller than the default 0.5 zoom the camera out; larger values zoom in.

How do I suppress console output during rendering?¶

Pass output=False to render():

video.render(output=False)

This disables progress bars and timing logs while still producing the video file.

Why does Manim caching not work?¶

CodeVideoRenderer internally sets config.disable_caching = True to prevent stale cache files from interfering with the code-typing animation. This is intentional and not a bug.

Why is my code slightly misaligned vertically?¶

Certain characters (acegmnopqrsuvwxyz+,-.:;<=>_~) trigger a known Manim text-layout alignment bug. CodeVideoRenderer automatically applies a workaround offset (CODE_OFFSET) for these characters. If you still see issues, try adjusting camera_scale or avoid those characters in critical positions.

Are tabs expanded? Can I change the tab size?¶

Yes — tabs are always expanded to spaces using a tab size of 4 (the DEFAULT_TAB_WIDTH constant). Currently this value cannot be changed at runtime; if you need a different tab size, preprocess your code string before passing it to CameraFollowCursorCV.

What happens if `video_name` is empty?¶

The constructor raises ValueError("video_name must be provided") if video_name is empty or falsy. Always provide a non-empty string.

Rendering is slow¶

Try renderer='opengl' if you have a compatible GPU.
Reduce the code length or split it into multiple shorter videos.
Ensure you are not running inside a very slow virtual machine without GPU passthrough.