Digital set-top box Hardware composition
(1) Network Interface Module (NIM): The network interface module performs channel demodulation and channel decoding to send a transport stream (TS) containing video, audio and other data information.
(2) source data transmission stream demultiplexer: the transport stream generally contains a number of audio and video streams and some data information, transport stream demultiplexer used to distinguish between different programs, extract the appropriate audio and video streams and data streams, Send video and audio decoder and the corresponding analysis software.
(3) Conditional Access Module: For pay TV, the conditional access module also performs descrambling on the audiovisual stream, and adopts a smart card containing a recognition user and a memory function to ensure that legitimate users watch normally.
(4) Video and audio decoder and post-processing: MPEG-2 decoder to complete the audio and video signal decompression, the video encoder and audio D / A transform, restore the analog audio and video signals, analog TV shows high quality Images, and provide multi-channel stereo programs.
(5) embedded CPU and memory module and interface circuit: embedded CPU is the heart of digital TV set-top box, it and memory module is used to store and run the software system, and each hardware module control. Interface circuit provides a wealth of external interfaces, including universal serial interface USB, Ethernet interface and RS232, analog, digital video and audio interfaces, data interface