title: ffmpeg with Videoconverter.js MTS to .mp4 conversion issue
body: <p>I've been scratching my head over this issue and going through dozens of google search results to find a solution to this, but no luck. I've got an issue when trying to convert MTS to mp4 with Videoconverter.js, which uses ffmpeg commands for converting video. I have installed ffmpeg, and run successfully .webm to .mp4 conversions. I've changed the Videoconverter.js file that specifies files to be used in the terminal, and I'm using commands from tutorials for MTS conversions (I've tried multiple options already), but to no avail. I keep getting "File not found", although it certainly is there, next to .webm which I converted before successfully. 
  Anyone know what this might be?</p>
  
  <pre><code>Worker has received command
  Received command: -i 00091.MTS -vcodec mpeg4 -b:v 15M -acodec libmp3lame -b:a 192k output.mp4.          Processing with 268435456 bits.
  ffmpeg version 2.2.1 Copyright (c) 2000-2014 the FFmpeg developers
    built on Jun  9 2014 20:24:32 with emcc (Emscripten GCC-like replacement) 1.12.0 (commit  6960d2296299e96d43e694806f5d35799ef8d39c)
    configuration: --cc=emcc --prefix=/Users/bgrinstead/Sites/videoconverter.js/build/ffmpeg/../dist --extra-cflags='-I/Users/bgrinstead/Sites/videoconverter.js/build/ffmpeg/../dist/include -v' --enable-cross-compile --target-os=none --arch=x86_32 --cpu=generic --disable-ffplay --disable-ffprobe --disable-ffserver --disable-asm --disable-doc --disable-devices --disable-pthreads --disable-w32threads --disable-network --disable-hwaccels --disable-parsers --disable-bsfs --disable-debug --disable-protocols --disable-indevs --disable-outdevs --enable-protocol=file --enable-libvpx --enable-gpl --extra-libs='/Users/bgrinstead/Sites/videoconverter.js/build/ffmpeg/../dist/lib/libx264.a /Users/bgrinstead/Sites/videoconverter.js/build/ffmpeg/../dist/lib/libvpx.a'
    libavutil      52. 66.100 / 52. 66.100
    libavcodec     55. 52.102 / 55. 52.102
    libavformat    55. 33.100 / 55. 33.100
    libavdevice    55. 10.100 / 55. 10.100
    libavfilter     4.  2.100 /  4.  2.100
    libswscale      2.  5.102 /  2.  5.102
    libswresample   0. 18.100 /  0. 18.100
    libpostproc    52.  3.100 / 52.  3.100
  00091.MTS: No such file or directory
  Finished processing (took 140ms)
  </code></pre>