Audio/video decoder
As more communication requires video, such as real-time streaming of video, video conferencing, digital television, interactive television and Internet-based communications, more efficient ways of utilizing existing bandwidth are needed. Because of the vast amount of data involved, which create a very heavy burden to the memory storage space and/or the transmission bandwidth, data compression is typically required so as to reduce the memory storage and/or bandwidth requirement. Compression allows digitized video sequences to be represented efficiently, allowing more video to be transmitted in a given amount of time over a given channel, or more video to be stored in a given storage medium. The MPEG standards are an evolving set of standards for video and audio compression developed by the Moving Picture Experts Group (MPEG). The MPEG-2 standard is used for various applications, such as digital television (DTV) broadcasts, digital versatile disk (DVD) technology, and video storage systems. MPEG2 supports interlaced video while MPEG1 does not. Therefore, MPEG2 is used for high quality video displaying on TV units. The MPEG4 standard is used for encoding, decoding and transmitting audio, video and computer graphics data. It supports content based bitstream manipulation and representation. In an MPEG decoder, a video signal is encoded by taking motion compensation adaptive prediction, discrete cosine transformation (DCT) and variable length coding in combination. The decoder accepts the MPEG-2 encoded video stream, decodes it back to a good rendition of the original sequence of images and sends the data in proper format to the television set or computer screen to be viewed. Digital encoding and decoding of high-definition video signals provides higher image resolution and more effective control of the storage, manipulation and display of the video signal over existing analog NTSC and PAL video systems. Video and/or audio compression devices, typically referred to as encoders, are used to encode a video and/or audio sequence before the sequence is transmitted or stored. The resulting encoded bitstream may then be decoded by a video and/or audio decompression device, typically referred to as a decoder, before the video and/or audio sequence is output. A typical decoder buffers data streams during variable and fixed delay. In particular, the depth of a buffer for variable delay is generally related to the delay in the decoder at a particular point in time. An important function of any modern digital communications system is error control coding. Error control coding is the field of communications that deals with techniques for detecting and correcting errors in a digital system. One frequently used scheme for error detection/correction is through the use of so-called Reed-Solomon codes. Reed-Solomon codes are non-binary systematic cyclic linear block codes. Reed Solomon (RS) codes are used for correcting errors and erasures in a wide range of systems, including compact disc (CD), digital versatile disk (DVD), digital video broadcast (DVB) and hard disk drives (HDD). A RS decoder is generally used for correcting errors generated during transmission in a digital communication system using a high definition television (HDTV), a digital versatile disc (DVD), or a compact disc (CD). A typical Reed-Solomon decoder is comprised of a syndrome generating block, an error polynomial block, an error location block, an error magnitude block, an error correcting block, and a delay block.
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