Most users want nothing more than the average on an export button to press to their own work then in the best possible quality saves. But codecs such as H.264 offer such a wide variety of settings that with a manual intervention usually much more to quality can bring out when the computer by default allows. Provided, however, that you know what you're doing. A nice German-language text from the Art University in Linz (!) Describes many H.264 parameters and gives tips on their correct use. Very informative, indeed.
Q&A über die neuen JVC HD-Cams GY-HM100U & HM700