Tutorial: Converting equirectangular VR footage into fisheye

There are many solutions for turning fisheye footage into equirectangular, but none when it comes to the reverse. We've created a tutorial that shows how to convert equirectangular footage into fisheye projection using FFmpeg. This has many advantages and uses, such as the ability to apply an alpha channel to your footage for passthrough and much more. 

First, you'll need to use FFmpeg. This is free open-source software, made up of a suite of libraries and programs for handling video, audio, and other multimedia files and streams. The key element is the command-line ffmpeg tool itself. This is at the heart of FFmpeg, and allows you to process video and audio files. 

You'll need the mask8k.png file: available here for download. 

Convert equirectangular projection into fisheye: 

In this example, we will use 8K footage. 

The command to use is: 

ffmpeg -i input_side_by_side_180_video.mp4 -i mask8k.png -filter_complex "[0:v]split=2[left][right]; [left]crop=4000:4000:0:0[left_crop]; [right]crop=4000:4000:4000:0[right_crop]; [left_crop]v360=hequirect:fisheye:iv_fov=180:ih_fov=180:v_fov=180:h_fov=180[leftfisheye]; [right_crop]v360=hequirect:fisheye:iv_fov=180:ih_fov=180:v_fov=180:h_fov=180[rightfisheye]; [leftfisheye][rightfisheye]hstack[stacked]; [stacked][1:v]overlay=0:0" -c:a copy -crf 15 output_fisheye_video.mp4

Instructions: 

• First, put your equirectangular video into an FFmpeg folder
• In the command above, replace  input_side_by_side_180_video.mp4 with the actual name of your video.
• In the command above, replace output_fisheye_video.mp4 with your chosen output name.

• In the folder path bar, type "cmd" to run the command prompt from the folder
• When the command prompt is open, copy and paste the above command and hit enter

Now you have perfect 180 SBS fisheye VR footage.