Ms-MacBook-Pro:Downloads M$ ffmpeg -i source_by_toonegeminielf-dazyyth.gif -c:v libx264 -r 30 -pix_fmt yuv420p source_by_toonegeminielf-dazyyth.mp4 -vf scale=1200:-2
ffmpeg version 3.1.3 Copyright (c) 2000-2016 the FFmpeg developers
  built with Apple LLVM version 7.3.0 (clang-703.0.31)
  configuration: --prefix=/usr/local/Cellar/ffmpeg/3.1.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-opencl --enable-libx264 --enable-libmp3lame --enable-libxvid --disable-lzma --enable-vda
  libavutil      55. 28.100 / 55. 28.100
  libavcodec     57. 48.101 / 57. 48.101
  libavformat    57. 41.100 / 57. 41.100
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 47.100 /  6. 47.100
  libavresample   3.  0.  0 /  3.  0.  0
  libswscale      4.  1.100 /  4.  1.100
  libswresample   2.  1.100 /  2.  1.100
  libpostproc    54.  0.100 / 54.  0.100
Trailing options were found on the commandline.
Input #0, gif, from 'source_by_toonegeminielf-dazyyth.gif':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: gif, bgra, 1200x843, 12.50 fps, 12.50 tbr, 100 tbn, 100 tbc
File 'source_by_toonegeminielf-dazyyth.mp4' already exists. Overwrite ? [y/N] y
[libx264 @ 0x7fdfa18aae00] height not divisible by 2 (1200x843)
Output #0, mp4, to 'source_by_toonegeminielf-dazyyth.mp4':
    Stream #0:0: Unknown: none
    Metadata:
      encoder         : Lavc57.48.101 libx264
Stream mapping:
  Stream #0:0 -> #0:0 (gif (native) -> h264 (libx264))
Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height