>ffmpeg ffmpeg -f dshow -i audio="virtual-audio-capturer":video="screen-capture-
recorder" yo.mp4 -s "1366x768" -r "30" -f alsa -ac 2 -vcodec libx264 -preset ult
rafast -s 1366x768 -acodec libmp3lame -ar 44100 -pix_fmt yuv420p -bufsize 1835k
-threads 2 -qscale 5 -b 712000 -f flv "rtmp://xxx.cast7.eu/onlive?key=THC87G/cas
t101"
ffmpeg version N-60161-g5554c6d Copyright (c) 2000-2014 the FFmpeg developers
  built on Jan 24 2014 22:06:41 with gcc 4.8.2 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
le-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetyp
e --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --ena
ble-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-l
ibopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libsp
eex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aa
cenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavp
ack --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  libavutil      52. 63.100 / 52. 63.100
  libavcodec     55. 49.100 / 55. 49.100
  libavformat    55. 26.100 / 55. 26.100
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     4.  1.100 /  4.  1.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
Guessed Channel Layout for  Input Stream #0.1 : stereo
Input #0, dshow, from 'audio=virtual-audio-capturer:video=screen-capture-recorde
r':
  Duration: N/A, start: 5848.788000, bitrate: 1536 kb/s
    Stream #0:0: Video: rawvideo, bgra, 1920x1080, 30 tbr, 10000k tbn, 30 tbc
    Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
[NULL @ 000000000285c580] Unable to find a suitable output format for 'ffmpeg'
ffmpeg: Invalid argument