Seamless Broadcast Of Audio And Video Directshow Architecture-based Design And Realization

Seamless Broadcast and caption processing are two basic requirement of the hard disk broadcast system.The traditional way is using hardware board card to realize the function.If we can get same effect by software method, the cost of hard disk broadcast system will be reduced, and it can improve the compatibility of broadcast system to each kind of program file. The syetem which can realize decoding, seamless broadcast, caption processing by software way and output signal by I/O card called Seamless Broadcast Player (SBP).In this thesis, the way of design and develop SBP basing DirectShow architecture on Windows OS has been introduced.Firistly, by researching switcher, captions card and Upper Levels Broadcast Control Software (ULBCS), the author explicited all kinds of requirement of SBP and made the proposal of SBP. The SBP is made up of Control Interface Module (CIM), Seamless BroadCast Subsyetem (SBS), Captions Processing Module (CPM) and Output Subsystem (OS).The CIM is the interface between SBP and ULBCS which can transmit order and get feedback. The fuction of SSS is seamless broadcast, and the CPM can add caption effect to seamless video stream which is made by the SSS. The OS can output both computer preview signal and TV broadcast signal.Additionally, introduce the way to realize each part of SBP in detail. It is based on DirectShow architecture of Windows OS to develop the SBP. GMFBridge is principal technology of SSS. To meet the need of SBP, we must modify it`s work logic. FirmBridgePT is a filter which is made by myself. It can add static or dynamic caption effect to video stream. The CIM defines all interfaces of fuction parts. It must match the interfaces of ULBCS. Using Active control, the OS output computer preview signal, and using DeckLink Extreme, it output SDTV signal.Finally, introduce the problem which was discovered in test procedure and our solution. The test procedure can check if our design and realization is correct, and the problem and solution in test procedure is valuable experience which is useful to develop the system in future.