title: ffmpeg throwing "Output file #0 does not contain any stream" when trying to make a slideshow out of images
body: <p>Im trying to create video streaming using phantomjs that create screenshots from a url then it will pipe the frames to ffmpeg so he can use it to stream the video to an rtmp url .
  here is what i tried so far :</p>
  
  <pre><code>phantomjs runner.js | ffmpeg -f image2pipe  -vcodec png -c:a copy -c:v libx264  -f flv rtmp://localhost/mystream
  </code></pre>
  
  <p>and here is the script : </p>
  
  <pre><code>var page = require('webpage').create();
  page.viewportSize = { width: 640, height: 480 };
  
  page.open('http://www.goodboydigital.com/pixijs/examples/12-2/', function () {
    setInterval(function() {
      page.render('/dev/stdout', { format: "png" });
    }, 25);
  });
  </code></pre>
  
  <p>and this is the output : </p>
  
  <pre><code>ffmpeg version 3.0.2 Copyright (c) 2000-2016 the FFmpeg developers
    built with Apple LLVM version 7.3.0 (clang-703.0.29)
    configuration: --prefix=/usr/local/Cellar/ffmpeg/3.0.2 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-opencl --enable-libx264 --enable-libmp3lame --enable-libxvid --enable-vda
    libavutil      55. 17.103 / 55. 17.103
    libavcodec     57. 24.102 / 57. 24.102
    libavformat    57. 25.100 / 57. 25.100
    libavdevice    57.  0.101 / 57.  0.101
    libavfilter     6. 31.100 /  6. 31.100
    libavresample   3.  0.  0 /  3.  0.  0
    libswscale      4.  0.100 /  4.  0.100
    libswresample   2.  0.101 /  2.  0.101
    libpostproc    54.  0.100 / 54.  0.100
  Output #0, flv, to 'rtmp://localhost/mystream':
  Output file #0 does not contain any stream
  </code></pre>