ffmpeg version N-34549-g13b7781, Copyright (c) 2000-2011 the FFmpeg developers
  built on Nov  6 2011 22:02:08 with gcc 4.6.1
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-runtime-cpudetect --enable-avisynth --enable-bzlib --enable-frei0r --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libfreetype --enable-libgsm --enable-libmp3lame --enable-libopenjpeg --enable-librtmp --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  libavutil    51. 24. 0 / 51. 24. 0
  libavcodec   53. 28. 0 / 53. 28. 0
  libavformat  53. 19. 0 / 53. 19. 0
  libavdevice  53.  4. 0 / 53.  4. 0
  libavfilter   2. 47. 0 /  2. 47. 0
  libswscale    2.  1. 0 /  2.  1. 0
  libpostproc  51.  2. 0 / 51.  2. 0

Seems stream 0 codec frame rate differs from container frame rate: 47.95 (5000000/104271) -> 23.98 (24000/1001)
Input #0, matroska,webm, from 'H:\Downloads\Sin City Recut and Extended cut 2005 720p x264 DTS dxva FLAWL3SS\Sin City Recut and Extended cut 2005 720p x264 DTS dxva FLAWL3SS.mkv':
  Duration: 02:21:45.21, start: 0.000000, bitrate: 6513 kb/s
    Stream #0:0(eng): Video: h264 (High), yuv420p, 1280x692, SAR 1:1 DAR 320:173, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
    Stream #0:1: Audio: dts (DTS), 48000 Hz, 5.1(side), s16, 1536 kb/s (default)
[buffer @ 039EEF00] w:1280 h:692 pixfmt:yuv420p tb:1/1000000 sar:1/1 sws_param:
[setsar @ 003AF9A0] a:1/1
[scale @ 003AF8A0] w:1280 h:692 fmt:yuv420p -> w:326 h:176 fmt:yuv420p flags:0x40200
[libvpx @ 043D0860] v0.9.7-p1
Output #0, webm, to 'zap.webm':
  Metadata:
    encoder         : Lavf53.19.0
    Stream #0:0(eng): Video: vp8, yuv420p, 326x176 [SAR 1:1 DAR 163:88], q=-1--1, 200 kb/s, 1k tbn, 23.98 tbc (default)
Stream mapping:
  Stream #0:0 -> #0:0 (h264 -> libvpx)
Press [q] to stop, [?] for help
frame=    0 fps=  0 q=0.0 size=       0kB time=00:00:00.00 bitrate=   0.0kbits/s
frame=    0 fps=  0 q=0.0 size=       0kB time=00:00:00.00 bitrate=   0.0kbits/s
frame=    6 fps=  4 q=0.0 size=       0kB time=00:00:00.25 bitrate=  14.2kbits/s
frame=   14 fps=  7 q=0.0 size=       0kB time=00:00:00.58 bitrate=   6.1kbits/s
frame=   22 fps=  9 q=0.0 size=      32kB time=00:00:00.91 bitrate= 289.4kbits/s
frame=   29 fps=  9 q=0.0 size=      32kB time=00:00:01.21 bitrate= 219.6kbits/s
frame=   39 fps= 10 q=0.0 size=      32kB time=00:00:01.62 bitrate= 163.3kbits/s
frame=   47 fps= 11 q=0.0 size=      32kB time=00:00:01.96 bitrate= 135.6kbits/s
frame=   53 fps= 11 q=0.0 size=      32kB time=00:00:02.21 bitrate= 120.2kbits/s
frame=   58 fps= 11 q=0.0 size=      32kB time=00:00:02.41 bitrate= 109.8kbits/s
frame=   65 fps= 11 q=0.0 size=      64kB time=00:00:02.71 bitrate= 194.7kbits/s
frame=   72 fps= 11 q=0.0 size=      75kB time=00:00:03.00 bitrate= 205.8kbits/s
frame=   79 fps= 11 q=0.0 size=      75kB time=00:00:03.29 bitrate= 187.6kbits/s
frame=   85 fps= 11 q=0.0 size=      95kB time=00:00:03.54 bitrate= 220.3kbits/s
frame=   93 fps= 11 q=0.0 size=     105kB time=00:00:03.87 bitrate= 222.8kbits/s
frame=  101 fps= 12 q=0.0 size=     105kB time=00:00:04.21 bitrate= 205.1kbits/s
frame=  107 fps= 12 q=0.0 size=     119kB time=00:00:04.46 bitrate= 217.6kbits/s
frame=  113 fps= 12 q=0.0 size=     119kB time=00:00:04.71 bitrate= 206.0kbits/s
frame=  120 fps= 12 q=0.0 size=     119kB time=00:00:05.00 bitrate= 194.0kbits/s
frame=  125 fps= 11 q=0.0 size=     119kB time=00:00:05.21 bitrate= 186.2kbits/s
frame=  131 fps= 11 q=0.0 size=     119kB time=00:00:05.46 bitrate= 177.7kbits/s
frame=  138 fps= 12 q=0.0 size=     151kB time=00:00:05.75 bitrate= 214.2kbits/s
frame=  145 fps= 12 q=0.0 size=     151kB time=00:00:06.04 bitrate= 203.9kbits/s
frame=  150 fps= 11 q=0.0 size=     151kB time=00:00:06.25 bitrate= 197.1kbits/s
frame=  156 fps= 11 q=0.0 size=     151kB time=00:00:06.50 bitrate= 189.5kbits/s
frame=  162 fps= 11 q=0.0 size=     151kB time=00:00:06.75 bitrate= 182.5kbits/s
frame=  169 fps= 11 q=0.0 size=     183kB time=00:00:07.04 bitrate= 212.1kbits/s
frame=  173 fps= 11 q=0.0 size=     183kB time=00:00:07.21 bitrate= 207.2kbits/s
frame=  177 fps= 11 q=0.0 size=     190kB time=00:00:07.38 bitrate= 210.9kbits/s
frame=  185 fps= 11 q=0.0 size=     190kB time=00:00:07.71 bitrate= 201.8kbits/s
frame=  197 fps= 12 q=0.0 size=     190kB time=00:00:08.21 bitrate= 189.5kbits/s
frame=  208 fps= 12 q=0.0 size=     190kB time=00:00:08.67 bitrate= 179.5kbits/s
frame=  214 fps= 12 q=0.0 size=     212kB time=00:00:08.92 bitrate= 194.2kbits/s
frame=  221 fps= 12 q=0.0 size=     212kB time=00:00:09.21 bitrate= 188.1kbits/s
frame=  226 fps= 12 q=0.0 size=     212kB time=00:00:09.42 bitrate= 183.9kbits/s
frame=  232 fps= 12 q=0.0 size=     212kB time=00:00:09.67 bitrate= 179.2kbits/s
frame=  238 fps= 12 q=0.0 size=     212kB time=00:00:09.92 bitrate= 174.6kbits/s
frame=  244 fps= 12 q=0.0 size=     244kB time=00:00:10.17 bitrate= 196.1kbits/s
frame=  249 fps= 12 q=0.0 size=     244kB time=00:00:10.38 bitrate= 192.2kbits/s
frame=  254 fps= 12 q=0.0 size=     244kB time=00:00:10.59 bitrate= 188.4kbits/s
frame=  262 fps= 12 q=0.0 size=     244kB time=00:00:10.92 bitrate= 182.6kbits/s
frame=  269 fps= 12 q=0.0 size=     276kB time=00:00:11.22 bitrate= 201.2kbits/s
frame=  274 fps= 12 q=0.0 size=     276kB time=00:00:11.42 bitrate= 197.6kbits/s
frame=  282 fps= 12 q=0.0 size=     276kB time=00:00:11.76 bitrate= 192.0kbits/s
frame=  289 fps= 12 q=0.0 size=     276kB time=00:00:12.05 bitrate= 187.3kbits/s
frame=  292 fps= 12 q=0.0 Lsize=     300kB time=00:00:12.17 bitrate= 202.0kbits/s

video:298kB audio:0kB global headers:0kB muxing overhead 0.900830%