WXIA-TV revamps content delivery
November 17, 2006
Gannett-owned NBC affiliate WXIA-TV in Atlanta, GA, has made some infrastructure changes for its delivery of content over its SD and HD broadcast channels.
The company is using a Snell & Wilcox Memphis encoder to ingest uncompressed HD content and enable file-based storage and flexible delivery of that content over its various channels. The Memphis encoder serves as a platform for real-time processing of HD-SDI signals, which are output as ASI streams onto the facility's Omneon Spectrum media server system for storage and subsequent playout in the appropriate format for each channel.
The Memphis encoder incorporates two technologies to provide high image quality at lower bit rates. Snell & Wilcox Ph.C phase correlation motion estimation technology and Prefix compression preprocessing together enable a high level of compression efficiency while also reducing noise and fine-tuning images to achieve a sharp and crisp picture quality. Both the Memphis and Omneon Spectrum systems support common SMPTE specifications. Their high level of interoperability enables WXIA-TV to maintain frame-accurate time codes, proper mapping of PCM and Dolby E to maintain audio phase, and full surround-sound capability.
WXIA-TV is feeding uncompressed HD signals into the Memphis system, which creates a high-quality MPEG-2 signal and places it within an ASI transport stream. The ASI stream is then passed to the Omneon Spectrum, where the MPEG-2 material is de-multiplexed and stored as a file-based asset. When required by a playout schedule, the HD clip is retrieved from storage and decompressed to create an uncompressed HD signal. This HD clip is simultaneously downconverted to provide an SD feed for playout.
The SD signal broadcast by WXIA-TV is devoted to NBC's Weather Plus, a digital weather channel. The primary program stream is output via an analog channel and a digital channel that offers HD wherever possible.
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