Just recently I bought Googles Chromecast. It’s astonishing which potential lies in it. Apps like Photowall or the fully-fledged Youtube integration are impressive, but seem to just show the tip of the iceberg.
Though the device is created with streaming services like Netflix and Hulu in mind, there are Apps available for streaming local content too. My Zyxel NAS is providing video files via DLNA/UPnP and the App LocalCast is able to send these over to the Chromecast.
Of course it would be boring if everything works out of the box, so Google created a hurdle by not supporting AC3 audio. In fact, only AAC codecs are playable. The best solution for this is to simply reencode the audio stream of your files with ffmpeg. First install ffmpeg and libfdk_aac via slacker. After that you can simply use a command like the following to convert the audio but leave the video untouched:
ffmpeg -i input.mkv -c:v copy -c:a libfdk_aac output.mkv
It takes some time, but as the NAS is online all the time, it’s easy to do a lot of this work at night while nobody uses the system. The same command works for mp4 containers.