EE Times NAB news...
Products pack MPEG -2 4:2:2 compression and fresh twists on encoding
-- NAB draws a new bag of tricks from servers
techweb.com
Junko Yoshida
03/23/98 Electronic Engineering Times Page 22
Copyright 1998 CMP Publications Inc.
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Hewlett-Packard Co. (Palo Alto, Calif.) has just launched new MediaStream Broadcast Servers and Disk Recorders with full-featured MPEG -2 4:2:2 solutions. Earlier this year, Tektronix Inc. (Wilsonville, Ore.) also introduced MPEG -2 4:2:2 upgrades for its Profile video file server. On the encoder front, DiviCom Inc. (Milpitas, Calif.) is launching new encoders with 4:2:2 and 4:2:0 capabilities. Its MV40 encoder also comes with an innovative dual-pass MPEG -2 encoding and look-ahead technology.
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Separating HP's MediaStream Broadcast server from its competitors, claimed Kovalick, is its full-featured MPEG capabilities, including jog and shuttle features, and "clean-cut, frame-accurate" editing based on full IPB frames. Reversing the common belief that full IPB-based MPEG streams cannot be edited, HP received what Kovalick called a "bullet-proof patent" on technologies that allow frame-accurate MPEG editing.
The patented "CleanCut" editing uses two MPEG -2 decoders, doing the frame-accurate editing on the fly by controlling and switching between two decoded streams of uncompressed video. "There is really no other way around it to do frame-accurate editing," Kovalick said. The servers use MPEG -2 encode/decode chips from IBM Microelectronics .
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In a DTV broadcast environment where studios must transmit multiple channels per 6 MHz using a different bit rate for each video stream, statistical mutliplexing to efficiently manage transmission bandwidth will be critical for encoders. Ben Stanger, a marketing manager at DiviCom, claimed his company has devised a unique microcode that makes possible a dual encoder "look-ahead" capability.
DiviCom uses two complete encoding engines. The lookahead encoder first determines picture complexity and provides the information to the multiplexer, which looks at picture complexity in all channels, assigns bit rates and sends the information back to the encoders. The second encoder compresses the video at the specified rate and sends the transport stream to the multiplexer.
The MV40 is based on C-Cube Microsystems' MPEG -2 DVx video processor. "A transition to high definition is clearly on our road map," said Stanger. |
