x265, FFmpeg CRF issues

leo@chessman ~/Videos/bbb $ ffmpeg -i /media/EXTRA2/bbb3d_sunflower_video3d_fullres_ffvhuff.mkv -filter:v stereo3d=sbsl:ml,scale=-1:1080 -c:v libx265 -preset:v veryslow -crf:v 15 -y bbb3d_sunflower_video2d_1080p_hevc.mkv
ffmpeg version N-39999-g8631603 Copyright (c) 2000-2014 the FFmpeg developers
  built on Feb 12 2014 19:06:50 with gcc 4.8 (Ubuntu/Linaro 4.8.1-10ubuntu9)
  configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-shared --disable-static --enable-avresample --enable-vda --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libcaca --enable-libcdio --enable-libdc1394 --enable-libfdk-aac --enable-libflite --enable-libfreetype --enable-libgme --enable-libgsm --enable-libiec61883 --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-libquvi --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-openal --enable-opencl --enable-opengl --enable-openssl --enable-x11grab --enable-zlib
  libavutil      52. 63.101 / 52. 63.101
  libavcodec     55. 52.101 / 55. 52.101
  libavformat    55. 32.100 / 55. 32.100
  libavdevice    55.  9.100 / 55.  9.100
  libavfilter     4.  1.102 /  4.  1.102
  libavresample   1.  1.  0 /  1.  1.  0
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
Input #0, matroska,webm, from '/media/EXTRA2/bbb3d_sunflower_video3d_fullres_ffvhuff.mkv':
  Metadata:
    ENCODER         : Lavf55.25.101
  Duration: 00:10:34.53, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: ffvhuff (FFVH / 0x48564646), yuv420p, 8000x2250, SAR 1:1 DAR 32:9, 60 fps, 60 tbr, 1k tbn, 1k tbc (default)
Codec AVOption crf (Select the quality for constant quality mode) specified for output file #0 (bbb3d_sunflower_video2d_1080p_hevc.mkv) has not been used for any stream. The most likely reason is either wrong type (e.g. a video option with no video streams) or that it is a private option of some encoder which was not actually used for any stream.
x265 [info]: using cpu capabilities: MMX2 SSE SSE2Fast SSSE3 SSE4.2
x265 [info]: Main profile, Level-4.1 (Main tier)
x265 [info]: WPP streams / pool / frames         : 17 / 8 / 3
x265 [info]: CU size                             : 64
x265 [info]: Max RQT depth inter / intra         : 3 / 3
x265 [info]: ME / range / subpel / merge         : star / 57 / 4 / 4
x265 [info]: Keyframe min / max / scenecut       : 25 / 250 / 40
x265 [info]: Lookahead / bframes / badapt        : 40 / 8 / 2
x265 [info]: b-pyramid / weightp / refs          : 1 / 1 / 5
x265 [info]: Rate Control / AQ-Strength / CUTree : ABR-200 kbps / 1.0 / 1
x265 [info]: tools: rect amp rd=6 lft sao-lcu sign-hide
Output #0, matroska, to 'bbb3d_sunflower_video2d_1080p_hevc.mkv':
  Metadata:
    encoder         : Lavf55.32.100
    Stream #0:0: Video: hevc (libx265), yuv420p, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 1k tbn, 60 tbc (default)
Stream mapping:
  Stream #0:0 -> #0:0 (ffvhuff -> libx265)
Press [q] to stop, [?] for help
x265 [warning]: specified frame type (-662572455) at 0 is not compatible with keyframe interval
q^C^C^CReceived signal 2: terminating.8kB time=00:00:00.31 bitrate= 981.0kbits/s
leo@chessman ~/Videos/bbb $