No Seek Tables in .m4a files

[Budgie]

Hi Simon,
I have a bunch of long (> 2hour) music downloads which are aac in .m4a container and due to my error when downloading they have no seek data. As a result I can only play the files from the beginning.

I am afraid my command line skills have left me, if they were ever there and am asking for help to add seek data using either ffmpeg or AtomicParsley, whichever is appropriate!

Grateful for any help you can give.
Regards and Happy New Year.
Budgie.