"Was hoping someone has mucked through this already.?Any help would be greatly appreciated."
You said in your post "This string does start the recording and is?confirmed to work.", but I don't know if that's part of the report you were given, or your own result...
Is the question "How do I send this command to the device?", or "How do I change the Base64 so I can change the username and password?"? (Or something completely different?)
For the former:
For the latter, there's a Base64 module in the files section here.
? - Chip
