In　order　to　control　the　complexity　of　H.264　encoder,　we　first　proposed　two　efficient　Complexity　allocation　and　control　(CAC)　algorithms　for　both　intra　and　inter　coding　respectively,　based　on　a　new　Rate-distortion-complexity　optimization　(RDCO)　framework　and　the　rearrangement　of　candidate　modes　according　to　the　local-edges　and　texture　analysis.　The　CAC　algorithms　can　be　performed　both　at　the　frame　level　and　the　Macroblock　(MB)　level;　then,　within　the　proposed　CAC　algorithms,　a　whole　complexity　scalable　control　algorithm　was　given.　Experimental　results　show　that　our　proposed　algorithm　can　make　an　appropriate　cut-off　point　for　the　candidate　modes　sequence　adaptively　according　to　current　energy　condition　of　a　mobile　device,　so　as　to　adjust　the　complexity　at　any　target　levels　with　minimum　degradation　in　video　quality.　This　can　prolong　the　operational　lifetime　of　the　battery　for　hand-held　devices.