Adobe Flash Media Server can encode and deliver On2 V6 and Sorenson Spark encoded video. Flash Player 8 and 9 support both codecs, while Flash Player 7 and earlier versions support only the Sorenson Spark codec.

You can create virtual directories on the server to store copies of video streams in each format. This lets your application deliver the highest quality content to clients based on their Flash Player version.

Consider an example: A user wants to play a stream and has Flash Player 8 installed, which can play On2 video. The client application requests the HappyStream.flv file. After contacting the server, Flash Player 8 determines the value of the Client.virtualKey property. The virtualKey property maps to the c:\streams\on2 directory, instead of the default c:\streams directory, so the server plays the HappyStream.flv stream encoded with the On2 codec.