Lorenzo's Blog About me

A Twitch bot to create memes and show them live

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During the dark side of quarantine, I had to keep my hands busy, and instead of writing on this blog (sorry!) I started streaming on Twitch instead. To add some interactivity with my viewers, I made my own bot to let my viewers create and display custom Images and GIFs with text… Basically, a Meme Generator! This is the story of designing it, building it in Go, and running it Heroku 🀩

See it in action:

The Bot Idea

The idea is simple. If you write on my chat while I stream something like:

!meme hello Hello Lorenzo!

It will show you something like this on my stream:

Example of a Meme generated using the Bot

Example of a Meme generated using the Bot

People could generate Memes based on what was happening on the screen, and since I have been playing a lot of Dead By Daylight, there were plenty of moments to have fun creating new images while I was running away from the killer. 😜

I have decided to make it using Go and hosting it on Heroku. If you want to skip straight to the app running, you can do it here and you can check the source code here, where you can follow the instructions on how to deploy it on your Twitch channel!

Building it was fun because it was challenging

I built this live while streaming and the viewers as rubber ducks! In general, there were a few challenges like: How do I connect to Twitch? How can I make an OBS show the Image? How do I generate Images in Go? How can I make it easy to deploy? and also, what should be the name of the bot? 🀣

In the end, I named it Koalalorenzo’s Twitch Meme Bot… LOL!

Twitch uses IRC for chat

In the beginning, I was thinking about using a full-blown Twitch Bot, but setting it up would have been way more complex than needed. Instead I have discovered that Twitch uses IRC (or sort of) for every stream. I don’t have to deal with authentication unless I need to write to the channel. Since the bot is just listening, I found a go module that would just listen to the IRC interface. Jackpot!

Ingredients: Goroutines, WebSockets, Go channels

I found out that the easiest way to show content on my stream was to use a specific widget in Open Broadcaster Software (OBS for friends). I discovered that almost all the streaming services are using a clever trick: Streamlabs, Sound Alert, and many others use a transparent HTML page to show images, content, and animations. This means that it is super easy for me to implement this and display a picture on my stream!

I figured out that I needed a little more than constantly refreshing the HTML page. I had to make my hands dirty with WebSockets in Go and connect them to some Go channel.

The approach follows: Once a new message reaches the Twitch bot, a goroutine will analyze it and generate the image. Once that is done, it will send a message containing the custom Image URL to the main go channel.

Then a function consumes messages from this main channel and sends them to various other channels, one for each WebSocket open. Like this:

%%{init: {'theme': 'default'}}%% flowchart TD; TPar[\"twitch.parser()"/]; IGa["GenerateMeme() 1st"]; IGb["GenerateMeme() 2nd"]; IGn["GenerateMeme() Nth"]; MainChannel{{"mainChannel queue"}}; WBC[/"channelPipe() broadcast"\]; NMSG([IRC Messages]) ==> TPar; TPar-- Starts a goroutine -->IGa; TPar-- Starts a goroutine -->IGb; TPar-- Starts a goroutine -->IGn; IGa-- sends Image URL-->MainChannel; IGb-- sends Image URL -->MainChannel; IGn-- sends Image URL -->MainChannel; MainChannel==>WBC; WBC--"channel 1"-->wsChannela["reader() (OBS Channel)"]; WBC--"channel 2"-->wsChannelb["reader() (Safari Channel)"]; wsChannela-- Web Socket -->B(["Web Page in OBS"]); wsChannelb-- Web Socket --->C(["Web Page in Safari"]);

Why this complex structure? πŸ˜… When a web page opens, using some JavaScript code (yeah, there is some spaghetti code here 🀫), there is a new WebSocket connection every time. If I open more, I need to broadcast (or funnel out) the Image URL to every single web page. For each WebSocket, there is a Go channel and a function that broadcasts the messages to all of them.

It might not be the best nor the most straightforward implementation, but it works… Please let me know with a PR or a comment if there is a better way!

Generating Images and GIFS, but FASTER!

This part was interesting, but I was lucky to find a Go module that would generate Images and GIFs based on text input. After inspecting the code of jpoz/gomeme was working fine for my case, it does exactly what I was planning to do… except for one minor detail: the image size and formats. Here is the issue:

James’s module supports GIFs, PNG, and JPEGs. Those formats could be quite heavy and slow to manipulate. One of the GIFs that I am using as an example, called yeah, it is a whopping 23MB in size! 😱 This file takes around 2-3 seconds to generate and display into OBS Browser Source and on my stream.

The solution is to implement WebP: a new image standard developed by Google that is way lighter than PNGs, JPEGs, and GIFs! During my test, the 23MB GIF became 4MB Animated WebP. It is still a big file, but it will be faster to process. πŸŽ‰

To do so I had to create my own fork of the module. Sadly, it requires GCC as there is no official image/webp package in the Go standard library… 😭 and on top of that, I was able to find only libraries using C code to deal with WebP and not with Animated WebP. So due to time constraints, I added support for WebP only for static Images… 🀞 hoping to upgrade to Animated WebP when the Go standard library implements them.

Using my fork of Jame’s Go module made some images faster, but I kept the source to display PNGs, JPEGs, and GIFs as I am not expecting people to use only WebP… I could improve the bot to render the images in WebP, but that is for another time, maybe! πŸ˜‰


In the full spirit of OpenSource, I opened a Pull Request on Github to merge my gomeme changes and contribute to the original project. 🀞 Maybe somebody else will use my WebP changes to make even more efficient Meme Images! 🀣 Kudos to James Pozdena for making it! ❀️

I have added a lot of other functionalities, like support for a basic Web UI, a WebHook with Basic HTTP Auth, and some JSON API to integrate with Apple Shortcuts… so that I can generate memes from my iPhone or from my Mac.

My Shortcut to generate Memes from my iPhone
My Shortcut to generate Memes from my iPhone

Building this was pure pleasure. I made something so that viewers can have some fun, just as a small project. I am happy that I gathered some feedback from some of my viewers after making it. Sadly I had very little time to stream on twitch recently, and therefore the project did not evolve anymore. 😭

…But if you see me live on my channel, feel free to say hello with a meme! ❀️ If you want to use the twitch meme generator, check out the README in the repo: I wrote instructions on setting it up and customizing it. There is even a quick button to deploy it to Heroku! πŸ˜‰