ffmpeg version 3.2.5-1~bpo8+1 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 4.9.2 (Debian 4.9.2-10)
  configuration: --prefix=/usr --extra-version='1~bpo8+1' --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --enable-gpl --disable-stripping --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --disable-libebur128 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libopencv --enable-libx264 --enable-shared
  libavutil      55. 34.101 / 55. 34.101
  libavcodec     57. 64.101 / 57. 64.101
  libavformat    57. 56.101 / 57. 56.101
  libavdevice    57.  1.100 / 57.  1.100
  libavfilter     6. 65.100 /  6. 65.100
  libavresample   3.  1.  0 /  3.  1.  0
  libswscale      4.  2.100 /  4.  2.100
  libswresample   2.  3.100 /  2.  3.100
  libpostproc    54.  1.100 / 54.  1.100
Input #0, matroska,webm, from 'pipe:':
  Metadata:
    encoder         : Chrome
  Duration: N/A, start: 0.000000, bitrate: N/A
    Stream #0:0(eng): Audio: opus, 48000 Hz, mono, fltp (default)
    Stream #0:1(eng): Video: vp8, yuv420p, 640x480, SAR 1:1 DAR 4:3, 16.67 tbr, 1k tbn, 1k tbc (default)
    Metadata:
      alpha_mode      : 1
[libvpx-vp9 @ 0x564cc6c12d20] v1.3.0
Output #0, webm, to 'new.webm':
  Metadata:
    encoder         : Lavf57.56.101
    Stream #0:0(eng): Video: vp9 (libvpx-vp9), yuv420p, 640x480 [SAR 1:1 DAR 4:3], q=-1--1, 200 kb/s, 24 fps, 1k tbn, 24 tbc (default)
    Metadata:
      alpha_mode      : 1
      encoder         : Lavc57.64.101 libvpx-vp9
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
Stream mapping:
  Stream #0:1 -> #0:0 (vp8 (native) -> vp9 (libvpx-vp9))
frame=   37 fps=0.0 q=0.0 size=       0kB time=00:00:00.50 bitrate=   7.0kbits/sframe=   38 fps= 13 q=0.0 size=       0kB time=00:00:00.54 bitrate=   6.5kbits/sframe=   46 fps= 13 q=0.0 size=       0kB time=00:00:00.87 bitrate=   4.0kbits/sframe=   53 fps= 13 q=0.0 size=       0kB time=00:00:01.16 bitrate=   3.0kbits/sframe=   56 fps= 12 q=0.0 size=       0kB time=00:00:01.29 bitrate=   2.7kbits/sframe=   59 fps=9.6 q=0.0 size=       0kB time=00:00:01.41 bitrate=   2.5kbits/sframe=   62 fps=9.2 q=0.0 size=       0kB time=00:00:01.54 bitrate=   2.3kbits/sframe=   65 fps=8.7 q=0.0 size=       0kB time=00:00:01.66 bitrate=   2.1kbits/sframe=   68 fps=8.4 q=0.0 size=       0kB time=00:00:01.79 bitrate=   2.0kbits/sframe=   73 fps=8.4 q=0.0 size=       0kB time=00:00:02.00 bitrate=   1.8kbits/sframe=   76 fps=8.2 q=0.0 size=       0kB time=00:00:02.12 bitrate=   1.6kbits/sframe=   79 fps=8.0 q=0.0 size=       0kB time=00:00:02.25 bitrate=   1.6kbits/sframe=   82 fps=7.7 q=0.0 size=       0kB time=00:00:02.37 bitrate=   1.5kbits/sframe=   85 fps=7.5 q=0.0 size=       0kB time=00:00:02.50 bitrate=   1.4kbits/sframe=   89 fps=7.3 q=0.0 size=       0kB time=00:00:02.66 bitrate=   1.3kbits/sframe=   94 fps=7.4 q=0.0 size=       0kB time=00:00:02.87 bitrate=   1.2kbits/sframe=   97 fps=7.3 q=0.0 size=       0kB time=00:00:03.00 bitrate=   1.2kbits/sframe=  100 fps=7.2 q=0.0 size=       0kB time=00:00:03.12 bitrate=   1.1kbits/sframe=  103 fps=7.1 q=0.0 size=       0kB time=00:00:03.25 bitrate=   1.1kbits/sframe=  106 fps=7.0 q=0.0 size=       0kB time=00:00:03.37 bitrate=   1.0kbits/sframe=  108 fps=6.9 q=0.0 size=       0kB time=00:00:03.45 bitrate=   1.0kbits/sframe=  111 fps=6.8 q=0.0 size=       0kB time=00:00:03.58 bitrate=   1.0kbits/sframe=  116 fps=6.9 q=0.0 size=       0kB time=00:00:03.79 bitrate=   0.9kbits/sframe=  119 fps=6.8 q=0.0 size=       0kB time=00:00:03.91 bitrate=   0.9kbits/sframe=  122 fps=6.7 q=0.0 size=       0kB time=00:00:04.04 bitrate=   0.9kbits/sframe=  125 fps=6.7 q=0.0 size=       0kB time=00:00:04.16 bitrate=   0.8kbits/sframe=  128 fps=6.6 q=0.0 size=       0kB time=00:00:04.29 bitrate=   0.8kbits/sframe=  131 fps=6.5 q=0.0 size=       0kB time=00:00:04.41 bitrate=   0.8kbits/sframe=  135 fps=6.5 q=0.0 size=       0kB time=00:00:04.58 bitrate=   0.8kbits/sframe=  139 fps=6.5 q=0.0 size=       0kB time=00:00:04.75 bitrate=   0.7kbits/sframe=  142 fps=6.5 q=0.0 size=       0kB time=00:00:04.87 bitrate=   0.7kbits/sframe=  145 fps=6.4 q=0.0 size=       0kB time=00:00:05.00 bitrate=   0.7kbits/sframe=  148 fps=6.4 q=0.0 size=     106kB time=00:00:05.12 bitrate= 169.5kbits/sframe=  150 fps=6.3 q=0.0 size=     106kB time=00:00:05.20 bitrate= 166.8kbits/sframe=  153 fps=6.3 q=0.0 size=     106kB time=00:00:05.33 bitrate= 162.9kbits/sframe=  157 fps=6.3 q=0.0 size=     106kB time=00:00:05.50 bitrate= 158.0kbits/sframe=  161 fps=6.3 q=0.0 size=     106kB time=00:00:05.66 bitrate= 153.3kbits/sframe=  164 fps=6.3 q=0.0 size=     106kB time=00:00:05.79 bitrate= 150.0kbits/spipe:: Function not implemented
frame=  167 fps=6.2 q=0.0 size=     106kB time=00:00:05.91 bitrate= 146.8kbits/sframe=  170 fps=6.2 q=0.0 size=     106kB time=00:00:06.04 bitrate= 143.8kbits/sframe=  171 fps=6.1 q=0.0 size=     106kB time=00:00:06.08 bitrate= 142.8kbits/sframe=  171 fps=5.1 q=0.0 Lsize=     161kB time=00:00:07.08 bitrate= 185.8kbits/s speed=0.213x
video:159kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.023667%