A sound card is not necessary now for Moyea SWF to Video Converter SDK.
We have added "-nosoundcard" option since Version 2.0 of the SWF to Video Converter SDK. If your server doesn't have sound card, you could use the "-nosoundcard" parameter in your command line and then try. But if you have sound card installed on your server machine, please don't use this option.
Besides, the new version supports well with Flash Player 10.1.
Download link: http://www.moyeamedia.com/download/swf2 ... _setup.exe
Product Page: http://www.swfkits.com/swf-to-video-sdk/