Coordinates Reader

Ruby on Rails webapp that reads a video that contains coordinates as text, updated per second, and produces a set of images, one per each coordinate change, with their corresponding coordinates by reading the text in the video.

• Coordinates Reader
  • Run with Docker
  • Build Docker image
  • Setup development environment
    • Start application
  • Run Tesseract manually
  • Run FFMPEG manually

Run with Docker

Pull image:

docker pull hamax97/coordinates-reader

Run in terminal:

docker run -d -e SECRET_KEY_BASE=$(bin/rails secret) -p 3000:3000 -h coordinates-reader --name coordinates-reader coordinates-reader:latest

TODO: Run in Docker Desktop.

Build Docker image

Build image:

docker build -t coordinates-reader .

Tag and push:

docker tag <image_id> hamax97/coordinates-reader:<version>
docker push hamax97/coordinates-reader:<version>

Setup development environment

Developed with:

• Ubuntu 20.04
• Ruby 3.2.0
• Rails 7.0.4
• PostgreSQL 12
• Text extraction: Tesseract version 5.3.0
• Video processing: FFMPEG version 7:4.2.7-0ubuntu0.1

Install Tessearct:

echo "deb https://notesalexp.org/tesseract-ocr5/focal/ focal main" >> /etc/apt/sources.list

wget -O - https://notesalexp.org/debian/alexp_key.asc | sudo apt-key add -
sudo apt-get update

sudo apt-get install -y tesseract-ocr=5.3.0-1 libtesseract-dev=5.3.0-1

Install FFMPEG:

sudo apt-get -y install ffmpeg=7:4.2.7-0ubuntu0.1

Install libraries used by rails for image processing:

# required for gem image_processing, which required for displaying images.
sudo apt-get -y install libvips42

Install PostgreSQL and set the password for user coordinates_reader to CoordinatesReader123*:

sudo apt-get install postgresql-12 postgresql-client-12

# set password to: CoordinatesReader123*
sudo -u postgres createuser -s coordinates_reader -P

Start application

Please note that bin/rails db:create db:migrate and bin/rails active_storage:install are run only once to initliaze the DB. After that, starting the PostgreSQL service and the rails server will work.

sudo service postgresql start
bin/rails db:create db:migrate

bin/rails server

Run Tesseract manually

tesseract -c load_system_dawg=0 -c load_freq_dawg=0 <path_to_image> out
tesseract -c load_system_dawg=0 -c load_freq_dawg=0 -c tessedit_char_whitelist="0123456789. -+" <path_to_image> out
tesseract <path_to_image> out --loglevel ALL tesseract.config

Useful links:

• Tesseract improving quality.

• Tesseract config files

• Tesseract patterns docs (look for the function read_pattern_list)

Run FFMPEG manually

• First frame:

ffmpeg -i example.mp4 -vframes 1 000000.png

• Rest of the frames:

ffmpeg -i example.mp4 -vf fps=1 %06d.png