Telnet.me.uk

Stream any video as coloured ASCII/ANSI art over telnet or netcat — and optionally spin a roulette wheel that drops each viewer into one of several streams at random.

You supply the video. asciivid renders it to a compact frame cache and serves it over a plain TCP socket, so anyone can watch it in their terminal:

telnet your-host 2323

It ships with a small set of systemd utilities so you can run many independent streams at once, each on its own port, managed by name — plus a standalone roulette telnet server that bridges players to those streams at random.

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Contents

• Requirements
• Quick start
• How it works
• The CLI
  • render — make a .dat
  • serve — stream a .dat
  • play — render + serve in one go
• Running as a service (multiple streams)
  • One-time install
  • Add a stream
  • List / remove streams
  • Managing instances directly
• Roulette telnet server
  • Backends
  • Running it directly
  • Configuration
  • Running as a systemd service
  • Notes
• Ports and networking
• Exposing it publicly
• Troubleshooting
• Credits & licence

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Requirements

• Python 3.8+ — for serve (no third-party packages). The roulette server needs only Python 3.7+, also standard library only.
• ffmpeg (and optionally ffprobe) on PATH — only for render / play. Serving a pre-rendered .dat needs Python alone.
• A client: telnet or nc (netcat). For the roulette wheel, an ANSI-capable client in a real terminal.

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Quick start

# 1. Render a video you have the rights to into a frame cache
python3 asciivid.py render input.mp4 --width 100 --fps 12 --out myclip.dat

# 2. Serve it
python3 asciivid.py serve myclip.dat --port 2323

# 3. Watch it (from anywhere that can reach the host)
telnet localhost 2323

Or do steps 1–2 in one command:

python3 asciivid.py play input.mp4 --width 100 --fps 12 --port 2323

Playback loops by default. Press Ctrl-C in the client to disconnect cleanly — your terminal is restored to its original state.

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How it works

asciivid splits the job into two stages so serving is cheap and instant:

1. Render (render) uses ffmpeg to decode the video, scale it down to a terminal-sized grid, and convert every frame to an ANSI string. All frames, plus metadata (size, fps, colour mode), are pickled and zlib-compressed into a single .dat file — the frame cache.
2. Serve (serve) loads a .dat and streams its frames over TCP with correct frame timing. It needs no ffmpeg and starts instantly, which makes it ideal for a long-running service.

Each client connection is handled in its own forked process, so multiple people can watch the same stream simultaneously.

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The CLI

asciivid.py has three subcommands. Run python3 asciivid.py <cmd> -h for the full option list.

render — make a .dat

Converts a video into a frame cache.

python3 asciivid.py render input.mp4 --out myclip.dat

Option	Default	Description
--width	100	Frame width in characters.
--height	0 (auto)	Frame height in rows. 0 derives it from the source aspect ratio.
--fps	12	Frames per second to sample and play back.
--color	ansi256	ansi256, truecolor, or mono.
--out	frames.dat	Output cache path.

Notes on choosing values:

• Width is the biggest lever on both quality and file size. 100 suits a normal terminal; 160–200 looks sharper on a maximised window but makes a bigger .dat.
• Height auto-derivation accounts for terminal cells being roughly twice as tall as they are wide, so circles stay round. Override with --height only if you want to force a specific grid.
• --color truecolor looks best on modern terminals (24-bit) but produces a larger cache and more bytes on the wire. ansi256 is a good default; mono is tiny and works everywhere.
• --fps higher than ~15 rarely helps for ASCII and inflates the cache.

Example — a crisp, full-colour render:

python3 asciivid.py render input.mp4 --width 160 --fps 15 --color truecolor --out hq.dat

The command prints the resolved grid size and final cache size, e.g.:

rendering input.mp4 -> 160x60 @ 15fps (truecolor)
wrote hq.dat: 900 frames, 2048 KiB compressed

serve — stream a .dat

Serves a pre-rendered cache over TCP.

python3 asciivid.py serve myclip.dat --host 0.0.0.0 --port 2323

Option	Default	Description
--host	0.0.0.0	Interface to bind. 0.0.0.0 = all interfaces.
--port	2323	TCP port to listen on.
--no-loop	(off)	Play once and disconnect instead of looping.

Stop the server with Ctrl-C.

play — render + serve in one go

Convenience command: renders to a temporary cache, serves it, and deletes the cache on exit. Takes the union of render and serve options.

python3 asciivid.py play input.mp4 --width 100 --fps 12 --port 2323

Handy for a quick one-off; for anything long-running, prefer render once and serve the resulting .dat (that's what the service does).

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Running as a service (multiple streams)

The repo includes a systemd template unit and three helper commands so you can run any number of streams as managed, boot-persistent services — each with its own name, port, and clip.

Files involved:

File	Purpose
asciivid@.service	systemd template unit (one file, many instances)
install-service.sh	one-time setup: user, code, unit, helper commands
asciivid-add	create & start a new stream by name
asciivid-ls	list all streams, their ports and state
asciivid-rm	stop & remove a stream

One-time install

Run the installer once. It creates an unprivileged asciivid user, copies asciivid.py into /opt/asciivid, installs the template unit, and puts the helper commands on your PATH (/usr/local/bin).

sudo ./install-service.sh

You do not name any streams here — instances are created on demand afterwards.

Add a stream

Each stream is created by name. asciivid-add expects a rendered .dat, not a raw video — render first, then add:

# render the clip
python3 asciivid.py render never-gonna-give-you-up.mp4 --width 100 --fps 12 --out /tmp/rickroll.dat

# create + start a stream called "rickroll" on port 2323
sudo asciivid-add rickroll /tmp/rickroll.dat 2323

Syntax:

sudo asciivid-add NAME /path/to/frames.dat PORT [HOST]

• NAME — letters, digits, -, _ only. Becomes the systemd instance asciivid@NAME; its description shows telnet-NAME.
• PORT — 1–65535. asciivid-add warns if another instance already uses it.
• HOST — optional bind address; defaults to 0.0.0.0.

Each stream gets its own directory under /opt/asciivid/instances/NAME/ containing a copy of the cache (frames.dat) and an env file with its port. The instance is enabled (starts on boot) and started immediately.

Add as many as you like, each on a distinct port:

sudo asciivid-add starwars /tmp/starwars.dat 2324
sudo asciivid-add badapple /tmp/badapple.dat 2325

List / remove streams

asciivid-ls

NAME                 PORT    STATE    UNIT
----                 ----    -----    ----
telnet-rickroll      2323    active   asciivid@rickroll
telnet-starwars      2324    active   asciivid@starwars

Remove one (stops it, disables boot start, deletes its directory):

sudo asciivid-rm rickroll

Managing instances directly

The helpers are thin wrappers around normal systemctl, so you can also drive instances by hand:

sudo systemctl restart asciivid@rickroll     # after swapping its frames.dat
sudo systemctl stop asciivid@rickroll
sudo systemctl start asciivid@rickroll
journalctl -u asciivid@rickroll -f           # live logs for one stream

To change the clip on an existing stream, replace its cache and restart:

sudo install -m 0644 /tmp/newclip.dat /opt/asciivid/instances/rickroll/frames.dat
sudo chown asciivid:asciivid /opt/asciivid/instances/rickroll/frames.dat
sudo systemctl restart asciivid@rickroll

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🎰 Roulette Telnet Server

A telnet server that spins a roulette wheel and drops you into one of six backend services at random. Connect, watch the wheel decelerate and lock in, then get bridged straight to whatever it landed on. When a backend finishes, you're returned to the wheel to spin again.

It pairs naturally with the asciivid streams above: run a handful of clips as services, point the roulette at their ports, and let viewers gamble on what they get.

Backends

The server proxies to six local ports:

Port	Service
2323	rickroll
2324	nyan-cat
2325	what-does-the-fox-say
2326	gangnam-style
2327	chocolate-rain
2328	baby-shark

These are expected to be listening locally and to stream their content over a raw TCP/telnet connection. The roulette server itself only handles the wheel and the proxying — bring your own backends (e.g. asciivid streams).

Running it directly

python3 roulette_server.py

Then, from another terminal:

telnet 127.0.0.1 6666

The wheel spins, locks onto a random backend, and bridges you through. Press Enter at the finish prompt to spin again, or q to quit.

Configuration

Edit the constants at the top of roulette_server.py:

• LISTEN_HOST / LISTEN_PORT — where the roulette server listens (default 0.0.0.0:6666)
• BACKENDS — the (host, port, name) list to spin between

If you set LISTEN_PORT below 1024, either run as root or grant the capability (see the systemd note below).

Running as a systemd service

A unit file (roulette.service) is included. It runs the server as a dedicated unprivileged user with a hardened sandbox.

# Place the script and create a service user
sudo mkdir -p /opt/roulette
sudo cp roulette_server.py /opt/roulette/
sudo useradd --system --no-create-home --shell /usr/sbin/nologin roulette
sudo chown -R roulette:roulette /opt/roulette

# Install and enable the unit
sudo cp roulette.service /etc/systemd/system/
sudo systemctl daemon-reload
sudo systemctl enable --now roulette.service

# Check status and follow logs
sudo systemctl status roulette.service
journalctl -u roulette.service -f

Adjust ExecStart, User, Group, and ReadOnlyPaths in the unit if you use a different path or user. For a privileged port (< 1024), add AmbientCapabilities=CAP_NET_BIND_SERVICE to the [Service] section.

Notes

• The wheel animation needs an ANSI-capable client; a plain socket dump won't render the colours or cursor moves.
• If the chosen backend isn't listening, you'll see an "unavailable" message and be returned to the wheel rather than dropped.
• The server is threaded and handles multiple concurrent players, each with their own independent spin.

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Ports and networking

• Each stream listens on one TCP port. Pick a distinct port per stream.

• Ports below 1024 (including the real telnet port 23) require a privileged bind. The template unit is hardened with no capabilities, so it can't bind low ports as shipped. To use port 23, add these two lines to the [Service] section of asciivid@.service, replacing the empty capability lines, then daemon-reload and restart:

  AmbientCapabilities=CAP_NET_BIND_SERVICE
  CapabilityBoundingSet=CAP_NET_BIND_SERVICE

• Confirm what's listening:

  ss -ltnp | grep asciivid

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Exposing it publicly

By default the service binds 0.0.0.0 (all interfaces), but reaching it from outside still depends on your network:

• Local firewall — open the port, e.g. sudo ufw allow 2323/tcp.
• Home network — forward the port on your router to the host's LAN IP; viewers connect to your public IP (curl ifconfig.me to find it).
• Cloud VM — open the port in the provider's security group as well as any host firewall.

⚠️ This is an unauthenticated public TCP service. It forks a process per connection with only light limits (LimitNOFILE, TasksMax), so a determined client could open many sockets. Fine for a fun demo; if you leave it up, put it behind a firewall allowlist, a reverse proxy with connection limits, or a private overlay network (e.g. a mesh VPN) rather than the open internet.

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Troubleshooting

Unit asciivid@NAME.service does not exist The template unit isn't installed. Run sudo ./install-service.sh, or install just the template:

sudo install -m 0644 asciivid@.service /etc/systemd/system/asciivid@.service
sudo systemctl daemon-reload

command not found when running asciivid-add Either the installer hasn't run yet, or sudo's restricted PATH excludes /usr/local/bin. Use the full path: sudo /usr/local/bin/asciivid-add ….

Permission denied running ./asciivid-add The copy in the repo isn't executable, and it's meant to be run from /usr/local/bin after install anyway. Run the installer, then call it by bare name without ./.

The stream starts but is empty / errors on load serve and asciivid-add take a .dat, not an .mp4. Render the video first with asciivid.py render.

Terminal looks garbled after connecting with an old client The server negotiates telnet character mode and uses the alternate screen buffer. Very old or non-standard clients may not honour this; nc always works.

Client hangs on connect Check the port is actually listening (ss -ltnp) and not blocked by a firewall between you and the host.

Roulette lands on a backend but shows "unavailable" That backend port isn't listening. Start the corresponding asciivid stream (or other service) on the port listed in BACKENDS.

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Credits & licence

• Streaming, telnet negotiation, the .dat format, the server, the roulette wheel, and the systemd utilities are original to this project.
• Rendering is delegated to ffmpeg (called as an external program; not bundled).
• Telnet character-mode negotiation follows RFCs 854/855/857/858. The ASCII luminance ramp and ANSI escape sequences are long-standing common techniques.

Licensed under the GNU General Public License v3.0. See the LICENSE file for the full text.