[matja]

Are they really JPEGs and MP3s, or just bitrot?

I've found https://github.com/ImpulseAdventure/JPEGsnoop useful to fix corruption but I haven't come across a non-standard JFIF JPEG unless it was intentionally designed to accommodate non-standard features (alpha channel etc).

[orbital-decay]

I personally never encountered JPEGs or MP3s which were totally unreadable due to the being encoded by ancient software versions, but the metadata in common media formats is a total mess. Cameras and encoders are writing all sorts of obscure proprietary tags, or even things like X-Ray (STALKER Shadow of Chernobyl game engine) keeping gameplay-relevant binary metadata in OGG Vorbis comments. Which is even technically compliant with the standard I think, but that won't help you much.

[LocalH]

> X-Ray (STALKER Shadow of Chernobyl game engine) keeping gameplay-relevant binary metadata in OGG Vorbis comments

Just, ew