Install ffmpeg with mini libraries

How do I install ffmpeg with the libffmpeg-mini library? If i try to install ffmpeg it automatically links to the full library. I have version 19.07.10

V19 is end of life and unsupported. Start by upgrading to a supported version

I can't, it's the last version supported by my TD-W8968

Should be supported with https://downloads.openwrt.org/releases/22.03.6/targets/bcm63xx/generic/openwrt-22.03.6-bcm63xx-generic-sagem_fast-2704n-squashfs-cfe.bin

Okay, I flashed the new firmware. The situation is the same as before, how can I proceed?

libffmpeg-mini is only a library (used by 3rd party apps)
For ffmpeg binary you either need the full or custom variants
If you don't have enough storage I suggest setting up https://openwrt.org/docs/guide-user/additional-software/extroot_configuration via usb port