Learn how to optimize videos and replace the larger original videos in your ebook.


An unnecessarily large-sized ebook can cost you:

  1. Inconvenience for your readers in downloading an unnecessarily large file,
  2. Rejections by ebook stores that have an imposed size limit,
  3. The possibility of file corruption, if your computer can't handle the file size.


Video optimization

Optimizing may involve changing formats, resampling (bit rate, frequency, etc), changing resolution, or downgrading quality. The latter may not necessarily be detectable to the human eye, especially when viewed on small screens. The idea is to reach the least quality and resolution possible while maintaining a high quality for your viewers.

Software options

  • Adobe Media Encoder is one of the most popular software options for encoding and optimizing video files. The software is not free and comes only as part of the Premiere Pro or After Effects subscription.
  • Handbrake is a free open-source software, available for Windows and Mac. You may download it from the following link: https://handbrake.fr/. We will show you how to optimize your videos with Handbrake here in this article.

Locate Imported Videos

If you have not yet added the videos you want to optimize to your ebook, then skip straight to step 2.

To open the folder that contains the video file:

  1. Click on the Support menu in Kotobee Author and select Open working directory
  2. Open the EPUB folder. 
  3. Open the video folder. Keep this window open.
    This folder contains all the videos in your ebook. Any changes made to these files will instantly take place throughout your ebook.  

Optimize the Videos

  1. Open Handbrake. 
  2. Drag and drop a video file from the Kotobee window we just opened to this Handbrake window. You will then have access to all the settings.
    It is possible to batch convert all the video files at once.
  3. Select Gmail Large or Gmail Medium from the list of Web presets. If time is a luxury in your hands, you can play around with different presets until you find the optimal size-quality combination. 
  4. Enter a new destination for the optimized file (desktop, for now, would be fine) Note: Do not change the file name.
  5. Check the "Web Optimized" option (below the file name).
  6. Click on Start Encode in the top control bar.

Handbrake will start optimizing your file. The time it takes depends on the length and resolution of the original file. Once the optimization is complete, you can replace the old large video files with the newer smaller files in Kotobee Author.

If you have not yet added the video to your ebook, go to Add a Video.

Replace the original video files

  1. Open Kotobee Author's working directory again. Click on the Support menu, and select Open Working Directory. Navigate to the EPUB/videos folder.
  2. Replace the old video files with the newly generated ones on your desktop. You can drag and drop or copy-paste.
  3. Save your Kotobee Author project.

If you check your ebook project's file size now, it should be significantly smaller.

For future videos, you can optimize them before adding them to the book, simply by following the instructions for optimizing videos with Handbrake.