How does your pc plays wim.tv videos?

So, when you first come on the wim.tv page was asked you to download a browser plugin, then you're able to watch videos. But what really happens in this process?  What you downoad is a gstreamer-based rtsp player, that receives multimedia contents from the network and allows the browser rendering them within a web page.

Real time streaming protocol and wim.tv

RTSP (http://tools.ietf.org/html/rfc2326) coupled with Real Time Protocol (http://tools.ietf.org/html/rfc3550) is the network protocol used by wim.tv to delivery videos to the end user. RTSP is a real live protocol, that means that the media supplier could create the video at the very same time it streams it. This is implemented by sending a single frame of the video at the time, so in every moment the server could decide what is the next frame to be sent. In the others web-based video streaming platforms each video is an indivisible file, that must be streamed as-is.

Then RTSP allows to insert advertisements within the video in a totally smooth way, without overlaying, switching through different streams or other tricks. In fact, when an adverticement starts, the player just keep on receiving and frames, without ever notice if those frames are part of the video or the adverdicement. Besides improving playback performances, this ensures the advertisers that end users cannot skip the adverticements.

Another thing wim.tv player is able to do is to decrypt encrypted videos. Pay per view premium videos are streamed in an encrypted form, and can be played only by authorized users. If a malevolent user tries to save video data from the network the only thing he could retrieve is video of solid gray frames. But if you're allowed to play the same video, wim.tv browser plugin will decrypt it for you. In that case, each frame of the video is received, decrypted and played. The entire operation is enough fast that you'll never notice that is happening when you watch a video.

Alessio Lagonigro