SlopEngine

SlopEngine generates vertical short-form videos from a topic.

The pipeline asks Gemini for a rewritten YouTube title, spoken narration, Pexels search keywords, and a visual search query. It then uses Edge TTS for narration, Whisper for word-level captions, Pexels for portrait background video, and MoviePy to render a 9:16 MP4. It can also upload the finished video to YouTube Shorts.

Outputs

Generated files go under outputs/ by default:

• <timestamp>-<topic>.mp4: rendered vertical video
• <timestamp>-<topic>.metadata.json: topic, generated title, script payload, word events, background files, output path, and YouTube upload metadata when present

Temporary media is created under /tmp/shorts_core by default and is cleaned after each run unless you pass --keep-temp.

Requirements

• Python 3.11+ recommended
• FFmpeg installed and available on PATH
• A Gemini API key
• A Pexels API key
• Optional: YouTube OAuth client secrets for upload

Install Python packages:

python3 -m pip install -r requirements.txt

For Whisper CUDA, avoid Python 3.14. Use a Python 3.12 environment and keep WHISPER_DEVICE=cuda in .env:

python3.12 -m venv .venv312
.venv312/bin/python -m pip install --upgrade pip
.venv312/bin/python -m pip install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cu130
.venv312/bin/python -m pip install -r requirements.txt
.venv312/bin/python shorts_core.py --upload

If your GPU driver needs a different CUDA wheel, choose the matching pip command from the PyTorch install selector.

If Whisper or MoviePy cannot read media, check FFmpeg first:

ffmpeg -version

Configuration

Copy the example env file and fill in your own keys:

cp .env.example .env

Do not commit real credentials. .env, client_secrets.json, and .youtube_token.json are ignored by git.

Required keys:

Variable	Purpose
GEMINI_API_KEY	Google AI Studio key for script, title, keywords, and Pexels query generation
PEXELS_API_KEY	Pexels API key for background videos

Common optional keys:

Variable	Default	Purpose
GEMINI_MODEL	gemini-2.5-flash	Gemini model for content generation
GEMINI_TIMEOUT_SECONDS	60	Gemini content generation timeout
EDGE_TTS_VOICE	en-US-AriaNeural	Edge TTS voice
EDGE_TTS_RATE	+7%	Speech rate
EDGE_TTS_PITCH	-3Hz	Speech pitch
EDGE_TTS_VOLUME	+0%	Speech volume
WHISPER_MODEL	base	Whisper model name
WHISPER_DEVICE	cpu	Whisper device. Keep cpu on Python 3.14 to avoid CUDA/Triton word-timestamp failures
SHORTS_OUTPUT_DIR	outputs	Rendered video and metadata directory
SHORTS_TEMP_ROOT	/tmp/shorts_core	Temporary media directory
CAPTION_FONT_PATH	auto-detected	Path to a scalable .ttf or .otf font
CAPTION_FONT_SIZE	220	Caption font size
BACKGROUND_MUSIC_PATH	blank	Optional local music file
BACKGROUND_MUSIC_VOLUME	0.12	Music volume multiplier

YouTube upload keys:

Variable	Default	Purpose
YOUTUBE_UPLOAD_ENABLED	false	Upload after rendering when true
YOUTUBE_CLIENT_SECRETS_FILE	client_secrets.json	OAuth client secrets file
YOUTUBE_TOKEN_FILE	.youtube_token.json	Stored OAuth token
YOUTUBE_PRIVACY_STATUS	private	private, unlisted, or public
YOUTUBE_CATEGORY_ID	22	YouTube category ID

Usage

Generate a video:

python3 shorts_core.py --topic "Why your 8-hour workday is failing"

Choose an output file:

python3 shorts_core.py --topic "The hidden cost of context switching" --output outputs/context-switching.mp4

Keep temporary media for debugging:

python3 shorts_core.py --topic "How cities became louder" --keep-temp

Use background music for one run:

python3 shorts_core.py --topic "Why old malls feel strange" --music ost.mp3 --music-volume 0.12

Upload after rendering:

python3 shorts_core.py --topic "Why your 8-hour workday is failing" --upload

If you omit --topic, the script prompts for a topic and optional output file.

Generated Titles

The YouTube title is not the raw topic. Gemini rewrites the topic into a shorter, more engaging title and stores it in script_payload.title inside the metadata file. Upload uses that generated title when metadata is present.

Example:

Topic: The '8-hour workday' is actually a scam designed for the 1800s, and it is destroying your productivity.
Generated title: Why Your 8-Hour Workday Is Failing

If a generated title is missing, SlopEngine falls back to the normalized topic and caps it at YouTube's 100-character limit without adding ellipses.

YouTube Upload

To upload, create an OAuth desktop client in Google Cloud and save the downloaded secrets JSON as client_secrets.json, or point YOUTUBE_CLIENT_SECRETS_FILE at the file.

On the first upload, the script opens a local OAuth flow and writes .youtube_token.json. Later uploads reuse that token when possible.

Upload metadata is merged into the rendered video's .metadata.json file:

{
  "youtube": {
    "video_id": "example-id",
    "url": "https://www.youtube.com/watch?v=example-id"
  }
}

Project Layout

Path	Purpose
shorts_core.py	Main pipeline, CLI, rendering, and upload code
requirements.txt	Python dependencies
.env.example	Safe config template
tests/	Unit tests
outputs/	Rendered videos and metadata

Verification

Run the project checks after Python changes:

python3 -m unittest discover
python3 -m py_compile shorts_core.py

For caption or visual changes, render a short sample and inspect at least one frame or preview video.

Troubleshooting

• GEMINI_API_KEY is required or PEXELS_API_KEY is required: set the missing key in .env.
• Gemini generate_content exceeded ... seconds: increase GEMINI_TIMEOUT_SECONDS in .env or retry later if Gemini is slow.
• Gemini high-demand warning: the script retries with another available generateContent model when possible.
• YouTube dependency error: install the packages in requirements.txt; upload needs google-api-python-client, google-auth-oauthlib, and google-auth-httplib2.
• Whisper CUDA or Triton timestamp errors on Python 3.14: use the Python 3.12 CUDA setup above, or set WHISPER_DEVICE=cpu.
• Captions render with the wrong font: set CAPTION_FONT_PATH to a real scalable font file.