Download original firmware from an URL: http://update.tvip.ru/stb/<model>/<os>/release/tvip_firmware.ota.zip
Here, model is mediacenter model, for ex. s410; os is OS type (android or linux-qt).

$ mkdir firmware

$ unzip -o -q tvip_firmware.ota.zip -d firmware

$ ls -l firmware/
total 8272
drwxr-xr-x   6 vovan  staff      204  7 фев 13:55 META-INF
-rw-r--r--   1 vovan  staff  3870617 29 фев  2008 boot.img
-rw-r--r--   1 vovan  staff   360464 29 фев  2008 bootloader.img
drwxr-xr-x  19 vovan  staff      646  7 фев 13:55 system

For Linux firmware, roofs is located in system folder.
/usr and /home in Linux-Qt firmware are SquashFS images.

If you need to add symlinks, you should edit the following file: META-INF/com/google/android/updater-script

Compress:

$ cd firmware
$ zip -r ../unsigned_tvip_firmware.ota.zip .
$ cd ..

To sign a package, you will need:

• Java Development Kit OpenJDK или Oracle JDK
• singapk.jar tool and platform keys sign_tools.tgz

Sign OTA:

$ java -jar signapk.jar -w key.x509.pem key.pk8 unsigned_tvip_firmware.ota.zip signed_tvip_firmware.ota.zip

Please note: the latest TVIP Mediacenters (v.501, v.110, v.6xx), that utilize firmwares with .signed.ota.zip extension, can not be manually signed. Please, contact TVIP sales department or your ressaler if you want to use modified firmware with these mediacenters.