H.264 with aac for both. Http live streaming on ios, progressive downloads on everything else... Seriously, why waste your time doing this solo? plenty of companies already do this stuff almost for free a lot better than you can do it by yourself. Ooyala or brightcove are good for web. Synctv does web and custom apps across every major platform (ios , android, pre, yahoo widgets, bluray, roku, etc...) You can waste months developing something not even close to as good.