Food Pre-Packaged in Vacuum Bags
I wouldn't advice either one.

If you sous vide from frozen, your cooking times are going to be off.  You might end up with it undercooked in the middle unless you significantly increase the cooking time.

And I've only done it in the packaging once.  Never again, as there was little to no flavor to it.  (no browning, no seasoning).  The only time that I might be willing to re-try it would be if I went to the partially-prepared section, and got the ones with marinade already in the bag.