This video going over how to get pet urine out of carpet suggests using the one item that, as a professional carpet cleaner, I would not recommend using to clean pet urine. Baking soda is a good deodorizer but it also has a pH of around 9 and is considered an alkaline. It's not the greatest thing to put in your carpet because it can react with the urine and cause color damage or discoloration of the carpet.
I clean carpet in Tampa FL and I go into a lot of homes where customers have applied baking soda to pet urine spots in the carpet. It temporarily lessons the odor but it does not neutralize it in any way. Once the baking soda is vacuumed away the urine crystals under the carpet, in the pad, will start to off gas more ammonia and you're right back where you started.
Baking soda also turns tacky as it dries and leaves significant residues on carpet fibers. This residue can easily attract more soils and create other problems for your carpet.
So how would I get pet urine out of carpet? If you don't have a specialty urine cleaner in the house I would recommend water. First, I wold dry up as much of the urine as possible . You can use a terry cloth towel or a stack of paper towels. Next I would pour room temperature water on the spot. Just plain water, No soap. No vinegar. No baking soda. I recommend using about 2 cups of water. Just pour it on and wait 30 seconds. Now dry it out. I suggest using a towel for this step. Place a folded towel on the spot and stand on it for about 30 seconds to 1 minute. Move the towel slightly and stand on it again. Continuethis until you have soaked up most of the water. Let it air dry and there should be no stain or odor.