ffmpeg -r 1000 -s 64x32 -f rawvideo -pixel_format rgb24 -i - -an -f mpegts -c:v libx264rgb -preset ultrafast -crf 0 -pix_fmt yuv444p -g 1 udp://10.42.11.153:12345

ffmpeg version 3.2.2 Copyright (c) 2000-2016 the FFmpeg developers
  built with gcc 6.2.1 (GCC) 20160830
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-avisynth --enable-avresample --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libass --enable-libbluray --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-netcdf --enable-shared --enable-version3 --enable-x11grab
  libavutil      55. 34.100 / 55. 34.100
  libavcodec     57. 64.101 / 57. 64.101
  libavformat    57. 56.100 / 57. 56.100
  libavdevice    57.  1.100 / 57.  1.100
  libavfilter     6. 65.100 /  6. 65.100
  libavresample   3.  1.  0 /  3.  1.  0
  libswscale      4.  2.100 /  4.  2.100
  libswresample   2.  3.100 /  2.  3.100
  libpostproc    54.  1.100 / 54.  1.100
Input #0, rawvideo, from 'pipe:':
  Duration: N/A, start: 0.000000, bitrate: 49152 kb/s
    Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 64x32, 49152 kb/s, 1k tbr, 1k tbn, 1k tbc
Incompatible pixel format 'yuv444p' for codec 'libx264rgb', auto-selecting format 'bgr24'
[libx264rgb @ 0x5608a4819760] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.1 Cache64
[libx264rgb @ 0x5608a4819760] profile High 4:4:4 Intra, level 1.3, 4:4:4 10-bit
Output #0, mpegts, to 'udp://10.42.11.153:12345':
  Metadata:
    encoder         : Lavf57.56.100
    Stream #0:0: Video: h264 (libx264rgb), bgr24, 64x32, q=-1--1, 1k fps, 90k tbn, 1k tbc
    Metadata:
      encoder         : Lavc57.64.101 libx264rgb
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264rgb))
ffmpeg: encoder/slicetype.c:1992: x264_rc_analyse_slice: Assertion `cost >= 0' failed.