Fix file generation

[owlet123]

• Filenames are generated binary - use decimal format "{0:014d}". If you are using the same value more times, use constant for better orientation in code.

• A new call rewrite previous files - do not lose old files, generate new files with a "unique" file name, or much better, a new call could generate files to new folder.

[andrejcermak]

FIXED in latets pull request