Encoder h263p [H.263+ / H.263-1998 / H.263 version 2]:
    Threading capabilities: slice
    Supported pixel formats: yuv420p
H.263p encoder AVOptions:
-umv               <int>        E..V.. Use unlimited motion vectors. (from 0 to 1)
-aiv               <int>        E..V.. Use alternative inter VLC. (from 0 to 1)
-obmc              <int>        E..V.. use overlapped block motion compensation. (from 0 to 1)
-structured_slices <int>        E..V.. Write slice start position at every GOB header instead of just GOB number. (from 0 to 1)
-mpv_flags         <flags>      E..V.. Flags common for all mpegvideo-based encoders.
   skip_rd                      E..V.. RD optimal MB level residual skipping
   strict_gop                   E..V.. Strictly enforce gop size
   qp_rd                        E..V.. Use rate distortion optimization for qp selection
   cbp_rd                       E..V.. use rate distortion optimization for CBP
-luma_elim_threshold <int>        E..V.. single coefficient elimination threshold for luminance (negative values also consider dc coefficient) (from INT_MIN to INT_MAX)
-chroma_elim_threshold <int>        E..V.. single coefficient elimination threshold for chrominance (negative values also consider dc coefficient) (from INT_MIN to INT_MAX)
-quantizer_noise_shaping <int>        E..V.. (from 0 to INT_MAX)

