Using the "make H.264" defaults in Blender:

x264 - core 118 - H.264/MPEG-4 AVC codec - Copyleft 2003-2011 - http://www.videolan.org/x264.html - options: cabac=0 ref=2 deblock=1:0:0 analyse=0x3:0x100 me=dia subme=6 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=1 weightp=2 keyint=18 keyint_min=10 scenecut=40 intra_refresh=0 rc_lookahead=18 rc=abr mbtree=1 bitrate=6000 ratetol=1.0 qcomp=0.60 qpmin=10 qpmax=51 qpstep=4 vbv_maxrate=9000 vbv_bufsize=1835 nal_hrd=none ip_ratio=1.41 aq=1:1.00