title: Error when initializing webcam with ffmpeg
body: <p>I am trying to set up a webcam and stream to localhost, using <code>ffmpeg</code>.</p>
  
  <p>Here is a command I put into a terminal:</p>
  
  <pre><code>ffmpeg -f alsa -ac 2 -i hw:1,0 -f v4l2 -s 1280x720 -r 10 -i /dev/video1 -vcodec libx264 -pix_fmt yuv420p -preset ultrafast -r 25 -g 20 -b:v 2500k -codec:a libmp3lame -ar 44100 -threads 6 -b:a 11025 -bufsize 512k -f flv rtmp://localhost:80/
  </code></pre>
  
  <p>And here is what happened:</p>
  
  <blockquote>
    <p>ffmpeg version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2000-2017 the FFmpeg developers
      built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609
      configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --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-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
      libavutil      54. 31.100 / 54. 31.100
      libavcodec     56. 60.100 / 56. 60.100
      libavformat    56. 40.101 / 56. 40.101
      libavdevice    56.  4.100 / 56.  4.100
      libavfilter     5. 40.101 /  5. 40.101
      libavresample   2.  1.  0 /  2.  1.  0
      libswscale      3.  1.101 /  3.  1.101
      libswresample   1.  2.101 /  1.  2.101
      libpostproc    53.  3.100 / 53.  3.100</p>
    
    <p>ALSA lib pcm_hw.c:1700:(_snd_pcm_hw_open) Invalid value for card</p>
    
    <p>[alsa @ 0x21c45c0] cannot open audio device hw:1,0 (No such file or directory)</p>
    
    <p>hw:1,0: Input/output error</p>
  </blockquote>