10 bytes? What an odd choice... 80-bit floating-point numbers. Hmmm...
Well, if they all follow the same pattern, maybe you could treat them as 128-bit (16-bytes) values, filled with trailing 0s.
I know I have the file format specs lying around, from a long time ago. Bacj then when I wanted to make a mulimediaplayer that could replay .WAV and .AIFF files on a Atari 8-bit computer, I think.
EDIT: never mind, I found an archived copy of the specs at the Internet Archive...
Here's some info about the "80 bit IEEE Standard 754 floating point number":
https://en.wikipedia.org/wiki/Extended_precision
And here's the ""IEEE 754 quadruple-precision binary floating-point format" for comparison:
https://en.wikipedia.org/wiki/Quadruple ... int_format
EDIT2: and aooarently, here's some conversion code icnluded:
http://muratnkonar.com/aiff/index.html