$ ffmpeg -h encoder=libx264 | head -4
Encoder libx264 [libx264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10]:
    General capabilities: dr1 delay threads 
    Threading capabilities: other
    Supported pixel formats: yuv420p yuvj420p yuv422p yuvj422p yuv444p yuvj444p nv12 nv16 nv21 yuv420p10le yuv422p10le yuv444p10le nv20le gray gray10le