Bilingual books are incredibly useful for language learners.
I’ll outline a simple process for creating your own bilingual books.
First, buy online or find a PDF of the book you want to turn into a bilingual. It must be in a language you’re learning.
Next, you’ll need to translate the text of the source PDF into the language you know.
As complex as it sounds, as easy it is. I used the free online service https://www.onlinedoctranslator.com/en/translationform. Simply upload the source PDF and receive a translated version (Google Translate is used). Of course, you can also just use Google Translate for documents with the same result.
For those who object to using Google Translate here. It’s true that automatic translations aren’t always perfect. But for our task it’s not a big deal. We use authentic source text, and it’s fine to use less perfect translation. Besides, automatic translations have improved significantly in recent years.
This step is a bit tricky and technical. You need to merge the two PDFs, but in a specific way.
You need to build a merged PDF where the source and translated PDF pages go interleaved. That is: 1st page source, 1st page translated, 2nd page source, 2nd page translated, and so on.
I used a pdftk tool for that
sudo apt install pdftk
and came up with a small automation script to do the job: prepare_joined.awk.
awk -f prepare_joined.awk source.pdf translated.pdf
combined.pdf as a result.
To do so just open the combined PDF in Google Chrome and hit Print.
The key point here is to use setting.
Now you can just print the final PDF on paper or put it to your Kindle. Enjoy your bilingual book!