>ffmpeg -f concat  -i help.txt -c:v libx264  -crf 19 out.mkv
ffmpeg version N-63843-g6d40849 Copyright (c) 2000-2014 the FFmpeg developers
  built on Jun  8 2014 22:02:04 with gcc 4.8.2 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
le-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-
libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsox
r --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx
--enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-decklink --enable-zlib
  libavutil      52. 89.100 / 52. 89.100
  libavcodec     55. 66.100 / 55. 66.100
  libavformat    55. 42.101 / 55. 42.101
  libavdevice    55. 13.101 / 55. 13.101
  libavfilter     4.  6.100 /  4.  6.100
  libswscale      2.  6.100 /  2.  6.100
  libswresample   0. 19.100 /  0. 19.100
  libpostproc    52.  3.100 / 52.  3.100
Input #0, concat, from 'help.txt':
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0: Video: h264 (High), yuv420p, 640x352, SAR 1:1 DAR 20:11, 25 fps, 25 tbr, 20k tbn, 50 tbc
File 'out.mkv' already exists. Overwrite ? [y/N] y
[libx264 @ 0429afa0] using SAR=1/1
[libx264 @ 0429afa0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
[libx264 @ 0429afa0] profile High, level 3.0
[libx264 @ 0429afa0] 264 - core 142 r2431 ac76440 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deb
lock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chro
ma_qp_offset=-2 threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1
 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=19.0 qcomp=0.60 qpmin
=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, matroska, to 'out.mkv':
  Metadata:
    encoder         : Lavf55.42.101
    Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv420p, 640x352 [SAR 1:1 DAR 20:11], q=-1--1, 25 fps, 1k tbn, 25 tbc
    Metadata:
      encoder         : Lavc55.66.100 libx264
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
Press [q] to stop, [?] for help
DTS -184467432147152928, next:320000 st:0 invalid dropping
PTS -184467432147152928, next:320000 invalid dropping st:0
DTS -184467432147112928, next:2320000 st:0 invalid dropping
PTS -184467432147112928, next:2320000 invalid dropping st:0
frame=  101 fps=0.0 q=-1.0 Lsize=     315kB time=00:00:03.96 bitrate= 651.1kbits/s
video:313kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.455353%
[libx264 @ 0429afa0] frame I:4     Avg QP:15.40  size: 16107
[libx264 @ 0429afa0] frame P:28    Avg QP:19.34  size:  5374
[libx264 @ 0429afa0] frame B:69    Avg QP:22.62  size:  1525
[libx264 @ 0429afa0] consecutive B-frames:  5.0%  4.0% 23.8% 67.3%
[libx264 @ 0429afa0] mb I  I16..4:  9.8% 80.3%  9.8%
[libx264 @ 0429afa0] mb P  I16..4:  1.1%  5.8%  0.8%  P16..4: 48.3% 20.3%  9.1%  0.0%  0.0%    skip:14.6%
[libx264 @ 0429afa0] mb B  I16..4:  0.2%  0.4%  0.1%  B16..8: 40.9%  5.4%  1.0%  direct: 1.7%  skip:50.4%  L0:38.2% L1:51.8% BI:10.0%
[libx264 @ 0429afa0] 8x8 transform intra:77.8% inter:78.8%
[libx264 @ 0429afa0] coded y,uvDC,uvAC intra: 73.3% 83.7% 43.7% inter: 13.5% 18.0% 0.4%
[libx264 @ 0429afa0] i16 v,h,dc,p: 22% 20% 13% 44%
[libx264 @ 0429afa0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 21% 20% 17%  5%  7%  7%  8%  8%  7%
[libx264 @ 0429afa0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 26% 19% 10%  5% 10%  9%  9%  6%  6%
[libx264 @ 0429afa0] i8c dc,h,v,p: 41% 24% 21% 14%
[libx264 @ 0429afa0] Weighted P-Frames: Y:0.0% UV:0.0%
[libx264 @ 0429afa0] ref P L0: 59.7% 13.2% 22.9%  4.2%
[libx264 @ 0429afa0] ref B L0: 87.3% 11.2%  1.5%
[libx264 @ 0429afa0] ref B L1: 97.0%  3.0%
[libx264 @ 0429afa0] kb/s:633.98