3. About DirectShow3.1. DirectShow System Overview Multimedia Puzzle Treatment Multimedia has several major puzzles: * Multimedia stream contains huge data, and these data must be handled very quickly * audio and video must be synchronized, so They must start or stop at the same time, and play * data at the same rate. * Data may come from a lot of sources, such as local files, networks, television broadcasts, and video cameras * There are various formats, such as AVI, ASF, MPEG, and DV * Programmer Unable to predict what kind of hardware device DirectShow's solution DirectShow is designed to solve all of these problems, and its main design is the diversity and synchronization problem of complex data transfer, hardware From the application, it is independent to simplify the development task of digital media applications on a Windows platform. To achieve data efficiently, dynamic video data is required, while DirectShow uses DirectDraw and DirectSound as much as possible to efficiently send data to the user's voice and graphics devices. Synchronization is achieved by adding timestamps in the media data. The DirectShow modular architecture makes it easy to manipulate the sources, formats, and hardware devices that changes the multi-end, in which the application only needs to combine and match multiple FILTERs to implement functionality. DirectShow provides Filter supports WDM-based acquisition and tuning devices, also supports the earlier VFW acquisition card and encoders written for ACM and VCM interfaces. The following figure shows the relationship between the hardware and software components supported by the application, DirectShow components, and DirectShow:
As shown in the figure, DirectSHOW exits the application with many complex devices, communicates and controls these devices out of the DirectShow's filter. DirectShow also provides the corresponding codec for some file format.
