Feature request: Automatically free up space on SD card by deleting old clips

[evilC]

Add an option such that when the SD card is full, the oldest file is deleted to make space.
Obviously, with no accurate timestamp, this is not completely trivial.
I would guess that file index could be used instead of timestamp, but I guess over time, unless the recordings were completely cleared, this would result in the indexes getting ever bigger. A quick glance at the code however indicates to me that filenames are a max of 128 characters, so this would leave us with billions of indexes, rendering this issue effectively moot (Although how long would a filename have to get for it to start to be a problem in the UI?)

If implemented (And if #96 / #99 ends up being merged), hot clips should not be deleted when freeing up space

[matyas-brenner]

This would be great for VRX4 as well