Unicode Lossful Format (ULF)

A deliberately silly text-based video format. ULF represents video frames using Unicode characters, choosing glyphs that visually resemble parts of the original image.

It supports audio, delta-frame compression, GPU acceleration, and MP4 export.

Comparison

Requirements

Python 3.10+.

Install the package (with all optional playback features):

python -m pip install "unicode-lossful-format[all]"

FFmpeg must be installed and available on your system PATH for MP4 export. It is an external system dependency and is not installed by pip or by any ULF extra. Verify it with ffmpeg -version before using ulf convert or ulf.convert().

Encode

ulf-encode input.mp4 output.ulf --size 80x40

Options

• --size WIDTHxHEIGHT: Character-grid resolution (default: 80x40).
• --fps N: Output frame rate.
• --font PATH: Font used for glyph matching.
• --every N: Encode every Nth source frame.
• --backend auto|vulkan|cpu: Select processing backend.
• --keyframe-interval N: Set the interval between full frames.
• --mute: Disable audio.
• --audio-waves N: Set audio reconstruction detail.
• --emojiless: Exclude emoji characters.
• --hackerman: Use printable keyboard ASCII characters only.
• --debug: Enable diagnostic output.

Play

ulf-play output.ulf

Options

• --window WIDTHxHEIGHT: Set playback window size.
• --font PATH: Select playback font.
• --backend auto|vulkan|cpu: Select playback backend.
• --mute: Disable audio.
• --debug: Enable diagnostic output.

Convert to MP4

ulf convert output.ulf output.mp4 --encoder auto --export-quality high

The legacy equivalent remains ulf-play output.ulf --export output.mp4.

Python API

The same options are available as keyword arguments, using underscores in place of CLI hyphens:

import ulf

ulf.encode("example.mp4", "example.ulf", size="80x40", backend="auto")
ulf.play("example.ulf", window="1280x720", mute=False)
ulf.convert("example.ulf", "example.mp4", encoder="auto", export_quality="high")

encode() derives an .ulf output path when its output argument is omitted. convert() requires FFmpeg on your system PATH, just like the CLI.

File format

ULF files use the .ulf extension and are stored as UTF-8 text.

The format uses the ULF/1.0 signature and supports full-frame and delta-frame video, with optional audio data.

Limitations

• Video is grayscale.
• Audio reconstruction is lossy.
• Visual quality depends on the selected font and renderer.
• Vulkan requires compatible hardware and drivers.
• MP4 export requires FFmpeg.
• Large resolutions can increase processing time and file size.

Have fun

ULF makes video less efficient on purpose.

Now with compression, GPU acceleration, sound, and MP4 export!