user14605: As I have no previous knowledge of video editing, I'm still struggling to get ffmpeg to work as I need.
I need to resize a video of any size and any aspect ratio to height a of 960px, then crop both sides to get a square of 960x960 where the original image would be centered. And now the tricky part for me, I need to duplicate this square, so they would be side by side as single output video of 1920 x 960 pixels.
It's not supposed to be 3D, only cardboard friendly.


user1871: Use
ffmpeg -i video.mp4 -filter_complex \
       "[0]scale=iw*sar:ih,setsar=1,scale=-1:960,crop=960:960,split[left][right]; \
        [left][right]hstack[sbs]"  -map "[sbs]" -map 0:a? out.mp4


14605: <p>As I have no previous knowledge of video editing, I'm still struggling to get <strong>ffmpeg</strong> to work as I need.</p>

<p>I need to resize <strong>a video of any size and any aspect</strong> ratio to height a of 960px, then crop both sides to get a square of 960x960 where the original image would be centered. And now the tricky part for me, I need to duplicate this square, so they would be side by side as single output video of 1920 x 960 pixels.</p>

<p>It's not supposed to be 3D, only cardboard friendly.</p>

<p><img src="https://i.imgur.com/qgxAabn.jpg" alt="visual explanation"></p>
 1871: <p>Use</p>

<pre><code>ffmpeg -i video.mp4 -filter_complex \
       "[0]scale=iw*sar:ih,setsar=1,scale=-1:960,crop=960:960,split[left][right]; \
        [left][right]hstack[sbs]"  -map "[sbs]" -map 0:a? out.mp4
</code></pre>
