I might have misunderstood you, but you don't have to cook the berries before you freeze them. Just wash/rinse, dry and measure into ziploc bags.
The best strawberry jam I ever made was one with no pectin. It had to be cooked longer and you can't fiddle with the sugar/berry ratio, but it was wonderfully fresh tasting.
Unfortunately, I haven't been able to locate the recipe. :?