HDMI Transfer

File Transfer over HDMI , turn a file into a video signal. Rebuild it on another computer with a capture card.

Quick start · Transfer speeds · Installation guide · Hardware setup · FAQ

HDMI Transfer encodes files into video frames displayed through an HDMI output. On the receiving computer, an HDMI-to-USB capture card captures those frames so the software can reconstruct the original file. The file payload travels through video; no network file share is required.

A browser-based sender, a USB capture-card receiver, fountain codes and a local Python/Flask web interface work together to move files between two computers.

Proof of concept (POC): this is an experimental project for demonstrating file transfer over HDMI video.

How it works

1. Choose a file in the browser sender or through the command line.
2. Display the encoded frames full-screen on the HDMI output connected to the capture card.
3. Receive through the local interface, then download the reconstructed file.

Why HDMI Transfer?

• Video transport: move a file between two computers using HDMI and a USB capture card.
• Standalone sender: open sender.html locally in a browser, with no Python installation on the sending computer.
• Browser-based reception: select a capture device, preview the signal, track progress, download files and browse history.
• Fountain codes: reconstruct a file from enough packets, even when some video frames are lost.
• Explicit settings: choose Balanced, Speed or Quality profiles and configure the encoding.
• CLI tools: send, receive, calibrate and benchmark for reproducible experiments.

Quick start

Docker

docker compose up --build -d --wait

Open http://localhost:5000

docker compose stop    # Stop; keep received files
docker compose start  # Start again

Native installation

1. Prepare the receiving computer

Install Git and uv, then open a terminal:

git clone https://github.com/Thunzyy/HDMI-transfer.git
cd HDMI-transfer

2. Launch

Windows — PowerShell or terminal:

.\start.bat

Linux / macOS — shell:

sh start.sh

The launchers install web dependencies into .venv, then start the server. The first launch requires access to dependency downloads. Open http://localhost:5000 and keep the terminal open. Stop the server with Ctrl+C.

Windows is the automated quality-gate platform. A POSIX launcher is provided for Linux/macOS; capture-card and driver compatibility must be checked on each system.

Manual commands, without a launcher

uv sync --locked --extra web
uv run --no-sync hdmi-web

3. Transfer your first file

1. Connect sender PC HDMI output → capture card HDMI input → receiver PC USB port.
2. Copy sender.html to the sending computer using an authorized method, then open it in a browser. It runs in offline mode by default.
3. On the receiver, open Receive, choose the capture card and select Fountain · Balanced · 2 bpc · Preview Low.
4. On the sender, choose a small test file and match the receiver’s protocol, profile and encoding settings.
5. Move the sender window to the display connected to the capture card. Click Start on the receiver, then Start transmission on the sender. The signal must fill the captured display.
6. Once reception is complete, use Download on the receiver. Stop the sender if it is still transmitting.

Need to load the sender over a LAN or test on a single PC? The step-by-step guide covers both options, display settings and common problems.

Choose your setup

Goal	Setup
Two PCs with no shared network	Local sender.html + local web receiver
Load the sender from the receiver on a trusted LAN	Start the server with --host 0.0.0.0, then open http://RECEIVER_IP:5000/sender
Test on one PC with an HDMI capture card	/sender/test — explicit local test mode
Automate sending or receiving	CLI commands

LAN mode uses the network to serve the interface. To avoid any network dependency between the two computers, prepare the standalone HTML file in advance. The local server exposes received files: restrict LAN access to a trusted network.

Profiles

Profile	Resolution	Target FPS	When to use it
Balanced	1920 × 1080	60	Recommended for your first transfer
Speed	1920 × 1080	240	A high-refresh-rate HDMI path and compatible capture card
Quality	3840 × 2160	30	Experiments with a 4K-compatible chain

Selecting Speed does not turn a 60 Hz capture card into a 240 Hz device. See calibration and signal checks.

Transfer speeds

The following are theoretical encoded-payload ceilings, not measured file-transfer speeds. They use Fountain, 2 bits per RGB channel, 8 × 8 pixel blocks, and assume every frame reaches the receiver at the stated cadence.

Profile	Resolution / effective FPS assumed	Payload per frame	Theoretical MB/s	Theoretical Mbps
Balanced	1920 × 1080 / 60	24,284 bytes	1.46	11.66
Speed	1920 × 1080 / 240	24,284 bytes	5.83	46.63
Quality	3840 × 2160 / 30	97,184 bytes	2.92	23.32

Actual useful-file throughput is lower because of Fountain redundancy, frame loss, calibration, decoding and file reconstruction. The browser caps sending to the detected display refresh rate: Speed on a 60 Hz path has the same theoretical ceiling as Balanced at 60 FPS. The capture card and receiver must also keep up. HDMI link bandwidth is not the file-transfer speed.

For a hardware measurement, transfer a known file, verify its SHA-256 result, and divide its size by the receiver's reported transfer duration. Include setup/calibration time separately when measuring total user wait time. Software benchmarks and Docker smoke tests do not measure HDMI throughput; the table above is not a hardware benchmark.

Scale comparison only, not a head-to-head benchmark.

Connection / example configuration	Rate (Mbps)	Equivalent MB/s
Bluetooth Classic, EDR 3 Mb/s mode	3	0.375
HDMI Transfer — Balanced	11.66	1.46
HDMI Transfer — Quality	23.32	2.92
HDMI Transfer — Speed	46.63	5.83
Wi-Fi 6 — Intel AX203, 2×2	1,200	150
USB 3.2 Gen 1 — USB 5Gbps	5,000	625

HDMI Transfer demonstrates a video-based file channel when a shared network is unavailable. For routine large-file transfers, a working Wi-Fi/Ethernet connection or suitable USB storage is generally a more practical choice.

FAQ

Can I transfer files with just an HDMI cable between two computers?

The receiving computer needs an HDMI input. Most PC HDMI ports are outputs, so an HDMI-to-USB capture card is required.

Do I need Internet access or a shared network?

Initial installation downloads dependencies. After setup, the file payload travels over HDMI. A local HTML sender and an already-installed receiver can operate without a shared network.

Is the transfer encrypted?

Video encoding and fountain codes are not encryption. Encrypt the file before sending it if confidentiality is required.

What throughput should I expect?

See Transfer speeds: the recommended Balanced configuration has a theoretical ceiling of 1.46 MB/s (11.66 Mbps) at 60 FPS. Actual file throughput depends on your hardware and protocol overhead; this POC does not guarantee that speed.

Why is the preview black, or why does decoding fail?

Check the capture source, close other applications using the card, verify the correct HDMI display and return to Fountain + Balanced + 2 bpc on both sides. See troubleshooting.

License

Licensed under the MIT License. Copyright (c) 2026 Thunzyy.