snippet-cast 0.1.33

Turn annotated Python snippets into narrated screencast videos.

snippet-cast

Turn an annotated Python snippet into a narrated screencast video.

Narration is written as trailing #: comments on the snippet's own lines, so the input stays valid, runnable Python:

def fib(n):             #: We define fib, taking one argument, n.
    a, b = 0, 1          #: Start from the first two Fibonacci numbers.
    for _ in range(n):   #: Loop n times.
        a, b = b, a + b  #: Advance the pair; b becomes the running sum.
    return a             #: Return a — the nth Fibonacci number.

Each #: line becomes one "beat": the code is revealed up to that line, the line is highlighted, and its narration is spoken. snippet-cast renders syntax-highlighted code frames with a progressive reveal, a Python-Tutor-style live variable panel, optional burned-in captions and a typing-in animation, synthesises speech per line, and stitches everything into an MP4 with ffmpeg.

Installation

Requires Python 3.10+ and ffmpeg (with ffprobe) on PATH.

pip install snippet-cast
# or
pixi add snippet-cast
# or
conda install -c munch-group snippet-cast

Usage

snippet-cast snippet.py -o out.mp4 --tts silent --subtitles   # fast, voiceless proof
snippet-cast snippet.py -o out.mp4 --typing --subtitles       # type each new line in
snippet-cast loop.py    -o out.mp4 --every --subtitles        # animate each loop iteration

Or from Python:

from snippet_cast import build

build("snippet.py", "out.mp4", tts="silent", subtitles=True)

Or in a Jupyter notebook — write the snippet directly in a cell instead of a separate .py file:

pip install snippet-cast[jupyter]

%load_ext snippet_cast.magic

%%snippet-cast -o out.mp4 --tts silent --subtitles
def fib(n):             #: We define fib, taking one argument, n.
    a, b = 0, 1          #: Start from the first two Fibonacci numbers.
    for _ in range(n):   #: Loop n times.
        a, b = b, a + b  #: Advance the pair; b becomes the running sum.
    return a             #: Return a — the nth Fibonacci number.
result = fib(7)          #: Call fib with seven; result becomes {result}.

The cell magic takes the same flags as the CLI and displays the rendered MP4 inline.

See SETUP.md for configuring the Piper (local) and ElevenLabs (cloud) text-to-speech backends, and snippet-cast --help for all options.

Development

This repository is built from the munch-group library template.

Initial set up

pixi run init

Get updates to upstream fork

Add upstream if not already added

git remote add upstream https://github.com/munch-group/snippet-cast.git

Fetch upstream changes

git fetch upstream

Either rebase your changes on top of upstream (cleaner history)

git rebase upstream/main

Or, merge upstream into your fork (preserves history)

git merge upstream/main

If you want to see what's changed upstream before applying:

git log HEAD..upstream/main

See the actual diff

git diff HEAD...upstream/main

Then push your updated fork:

git push origin main

If you rebased and need to force push

git push origin main --force-with-lease