[工作點滴] The realtime of transport stream on Miracast
When I google the internet with realtime and transport stream, I could not find the information I want. The word ‘realtime’ must construct on the relative thinking. For example, there is camera and screen and the camera’s video can be showed on the screen with quite small latency. We assume the latency is under 150ms or 300ms whatever and we can call this is realtime or not when we can have comparisons. The structure of the transport stream or what we call MPEG-TS is not that simple. What I say is compare with raw encoded media direct push to intermedia. Maybe the transport stream is design for broadcasting usage, so the media stream can be selected and video can be smooth played are much more important than realtime. Because people would not feel any latency happened when they just watch TV. If we want to convert raw encoded media to transport stream. First, we have to packetize the raw encoded media to packetized elementary stream(PES). Second, we handle the PES by the muxing, splitting to small slice AV data…etc to program stream or what we call transport stream. Finally, we send the transport stream to internet or satellite for people to receive and watch it on display. These steps create lots of latency and make us feel it’s not realtime enough. Let’s go back to the definition of the Miracast. It is to convert the raw encoded media stream to transport stream and then encapsulate the stream to RTP. Finally go through the wifi directly to display. I’m not sure how many latency will be created? Maybe someone can tell me.