A realtime software solution for resynchronizing filtered MPEG2 Transport stream

With the increasing demand and popularity of multimedia streaming applications over the current Internet, manipulating MPEG streams in a real-time software manner is gaining more and more importance. In this work, we studied the synchronization problem that arises when a gateway changes the data content carried in an MPEG2 Transport stream. In short, the distance between original time stamps will be changed non-uniformly when the video frames are resized, and decoders will fail to reconstruct the encoding clock from the resulting stream. We propose a cheap software real-time approach to solve this problem, which basically reuses the original time stamp packets and adapts their distance to accommodate the changes in bit rate. Experimental results from a real-time HDTV stream filter shows that our approach is correct and efficient.