Spherical / stereoscopic video support

First, thanks for building this library. It's been immensely useful. Second, apologies if Github issues is not meant for questions like this. If so, kindly redirect me!

Question: Is there an API in mediabunny for reading/writing the "side data" field seen in ffprobe output?

Context: I work with 360º mp4 files exported using Insta360 Studio. These files contain "Side Data" that is critical for signaling to players (like VLC or YouTube) that this video should be rendered/uploaded as a 360º video. In VLC, for example, this "unwarps" the video and enables the viewer to pan/zoom freely during playback.

[I'm happy to DM you a link for a small 10-sec sample file if that'll be helpful]

Example ffprobe output with Side Data field at the very end:

> ffprobe 360-sample.mp4
ffprobe version 8.1.2 Copyright (c) 2007-2026 the FFmpeg developers
....
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '360-sample.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf60.3.100
  Duration: 00:00:10.03, start: 0.000000, bitrate: 1319 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuvj420p(pc, bt709, progressive), 3840x1920, 1317 kb/s, 30 fps, 30 tbr, 30k tbn (default)
    Metadata:
      handler_name    : VideoHandler
    Side data:
      Stereo 3D: 2D, view: packed, primary eye: none
      Spherical Mapping: equirectangular 

Here is a sample ffmpeg command that mutes a video while preserving side data:

ffmpeg -i 360-sample.mp4 -map 0:v:0 -c:v copy -an -strict experimental 360-sample-copy.mp4

Note: if you drop -strict experimental from the command, the side data will be missing from the output video.

Many thanks!