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High Picture Quality at Low Bitrates

It is no exaggeration to say that compression is the key technology that makes digital video feasible. The reason is simple: digital video generates astronomical numbers of bits. Uncompressed, a single second of SD video comprises about 250 megabits of data (480 lines/frame x 720 pixels/line x 24 bits/pixel x 30 frames/second). HD formats (1080 lines/frame x 1920 pixels/line) multiply this number by another factor of six, generating 1.5 gigabits of data every second. Uncompressed, a 2 hour HD movie adds up to 10.8 terabits (1.35 terabytes) of data. There is no commercially feasible technology that allows bits to be either transmitted or stored in such overwhelming numbers. (See Digital Video Basics for more information.)

For this reason, it is more than merely desirable to compress digital video. Compression is the essential precursor to any other operation on a digital video stream. Fortunately, because most bits are either redundant or unimportant in video data, video compression is an extremely powerful technology. Using advanced compression technology like H.264/AVC, it is literally possible to discard 99 out of every 100 bits in an uncompressed source and still retain excellent video quality. (See Video Compression Basics for more information.)

The goal for video compression technology can be stated simply: to eliminate bits in inverse order of their importance to picture quality. In practice, this means that an encoder should generate the best possible pictures for any given bit rate. An HD video stream compressed to 15 Mbps (a 100:1 reduction from uncompressed source at 1.5 Gbps) clearly cannot retain all the information in the original source stream, but the differences from the original ought to be as close to undetectable by the human visual system as possible. Further compression of the same stream ought to result in graceful degradation of video quality, achieving the best picture possible at each lower bit rate. For example, the video quality at 5 Mbps (a 300:1 reduction) ought to retain as much quality as possible despite additionally eliminating two out of every three bits in the 15Mbps stream. (See Digital Color Coding for an example of "lossy" compression, where key information is retained and less important information is discarded.)

This goal is precisely the ambition behind Telairity encoders, which use Telairity's exclusive hardware and software encoding technology, including the massively parallel multi-core, multi-thread TVP video processor and associated direct execution AVClairity software, to achieve industry-leading picture quality for both HD and SD formats at the lowest bitrates available. More specifically, Telairity offers three versatile multi-format encoding systems: a 1RU half-width "go anywhere" single-channel contribution encoder, the BE8600; a 1RU full-width multichannel low bitrate distribution encoder, the BE8700, capable of scaling from 1 to 4 channels; and a high-reliability, blade-based integrated encoder/transcoder system that scales from 4 to 32 channels in a 14RU telco-grade ATCA chassis, the SES3200.