The office gif bot

A telegram bot to create gif for every situation with the inline interface.

Build your own

In order to have your bot you'll need:

Rails >= 6
ffmpeg (with ogg, subtitles, and libx264)
your domain (if using telegram)
telegram bot credentials
the video you want to use with subtitles

Creation of usable videos

ffmpeg is great, but if you're not working on a daily basis with video coded it might sound a little complex.

In order to make the bot work you need to answer the query within a couple of seconds. This mean you have to use ffmpeg only with super fast commands.

Burning subtitles is not a fast command. So you need to do it as a first step. Take the subtitles and burn them into the video.

Extract subtitles

# code to parse file title
exec('ffmpeg')

Burn subtitles

exec('ffmpeg')

Note: While burning subtitles the frame is shrinked to a suitable dimension for the gifs.

While not saving the video in mp4 and just cut it?

For how the libx264 encode the video you can't cut it "frame perfect". Under the hood h264 uses techniques such as motion compensation and so to cut "frame perfet" you have to re-encode it.

This is why I choosed to encode it first to .ogg and then to .mp4 (even the ogg compression is 10 times larger than the mp4)

Why not keep all ogg? Telegram requires either .gif or .mp4 to be sent as gifs.

Database seeding

Once the DB is created you need to seed it with the subtitles extracted previously. I've created a seed task for that, so run:

rails db:seed

and it will take one by one all your .srt files in the folder data and seed the db.

This seed is not smart, it just saves the times of the subtitles and the sentence inside it.

It extracts the season and episode from the subtitle name (expect it to be in S01E01 format) also it expect to have the .ogg file with the same name.

Deploy telegram bot

Afer inserted all the credentials in the server, and having a https connection active on your server you can run

bin/rake telegram:bot:set_webhook RAILS_ENV=production

and automatically set the webhook. Check telegram-bot gem for full documentation.

Dry run test

In the main page you can test your bot with the form.

Extra

TBI

Saving all queries and keep only most used gifs to save space.
Compressing existing .mp4 using -preset veryslow in background to optimize existing gifs

Enjoy!

Scaffale/theofficebot2