Files with the extension .SA1 are panasonic 'AAC' files data wrapped in SD (secure digital) audio encryption layer.

AAC files (Advanced Audio Coding) is a standardized, lossy compression and encoding scheme for digital audio. The AAC format was designed to replace the MP3 format.

An .SA1 file is an AAC file wrapped in a SD audio encryption layer and is used by Panasonic for digital rights management.