8. History: Transition to MPEG2 and Beyond:
Although all set-top boxes, technically known as Integrated Receiver-Decoders or IRDs, included full MPEG2 decoding hardware, until the fall of 1995, the actual signals transmitted were in the older "MPEG1+" format, using the MPEG2 syntax. The IRDs are backward compatible with MPEG1, which is for practical purposes, a subset of MPEG2. IRDs automatically operated with full MPEG2 compatibility without any change required, as the MPEG2 encoders were gradually put on-line late in the summer of 1995.
In April 1997, DirecTV added additional channels to its DBS services, including increasing the number of channels carrying pay-per-view. More barker (preview) channels with motion video were also added to the system. At the same time, the encoder firmware (software) was enhanced.
In 1998, HDTV (high definition television) debuted on DirecTV as did Dolby AC-3 (5.1) surround sound audio, which was only available on a few pay-per-view channels and occasionally on one of the Starz network channels. This was because AC-3 requires significantly more scarce satellite resources than normal stereo audio.
DirecTV continued to expand. The commercial network feeds were considerably augmented from the original New York and Los Angeles locations, providing signals from many local markets. Development of new technology augmented the capabilities of the statistical multiplexers, permitting fine tuning of the MPEG2 algorithms on each encoder dynamically.
A new satellite parking location was added, west of the original constellation, that includes foreign language programming, HDTV, NASA and some of the local network affiliate stations.
The New Millenium
DirecTV has continued to expand the length and breadth of both its program and media offerings. Spot beams were introduced on satellites, allowing each major city and environs to receive the local programming from its own local-market stations. This change though did inconvenience many located outside the main city areas. However, local signal coverage gets into aspects governed by new laws, politics and so forth, well beyond the scope of this paper.
In a similar vein, in the early days, theft of telecommunications was rampant because of the relatively weak encryption initially used. Current systems have much enhanced security making it very difficult, if not impossible, to receive programming without the proper "electronic" credentials.
DirecTV has added another satellite which will be dedicated to high quality services using MPEG4 sound and video encoding. Similarly, there is a steady evolution towards HDTV, due to be fully implemented this decade.
DirecTV continues its growth and evolution, and in general continues to provide good quality service. Picture quality is still far better than analog cable and VCR tapes although not up to the level of DVDs. But all in all, their quality is very good and trouble-free.
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