Pulse or digital communications – Bandwidth reduction or expansion
Reexamination Certificate
1997-07-29
2001-08-21
Kelley, Chris (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
C375S213000, C725S114000, C725S131000, C725S067000, C345S215000
Reexamination Certificate
active
06278733
ABSTRACT:
BACKGROUND OF THE INVENTION
A conventional analog television waveform such as the system defined by the National Television Standards Committee (NTSC), used in the United States and certain other countries such as Canada, Japan and Korea, and the Phase Alternate Line (PAL) system used in most European countries and certain other countries such as Australia, includes a standard number of horizontal scanning lines that contain video information intended for display by a television receiver. However, the first several lines, referred to as the vertical blanking interval (VBI), are used to transmit test and reference signals as well as data services.
Significant efforts have been made to establish standards for transmission of digital representations of video and audio data in various media. The International Organization for Standardization (ISO) has adopted a standard (ISO/IEC 13818-1) that addresses the combining of one or more “elementary streams” of video and audio, as well as other data, into single or multiple streams suitable for storage or transmission. The ISO/IEC 13818-1 standard, hereinafter referred to as the “MPEG-2 Systems” standard, is described in detail in the ISO draft document “Generic Coding of Moving Pictures and Associated Audio”, ISO/IEC JTC1/SC29/WG11 N0801 (Nov. 13, 1994), which is incorporated herein in its entirety by reference. However, in order to replace conventional analog broadcasting systems it is also necessary to define encoding means for the signals carried in the VBI, so that they may be reconstructed by the receiving equipment and decoded by conventional analog equipment.
Standards have been established for representation and transport of Teletext in MPEG2 by the Digital Video Board (DVB), which is the predominant user of the VBI in 625-line systems in Europe, particularly in consumer applications. See “Digital Broadcasting Systems for Television Sound and Data Services; Specification for Conveying ITU-R System B Teletext in Digital Video Broadcasting (DVB) Bit streams”, ETS 300 472, May 1995 (hereinafter DVB Teletext). However, no standards have been defined by DVB or other bodies to handle representation and transport of other types of VBI signals, such as Vertical Interval Test Signal (VITS), Vertical Interval Reference (VIR), Ghost Cancellation Reference Signals (GCR), North American Broadcast Teletext System (NABTS), Line 21 Closed Captioning (CC), Vertical Interval Time Code (VITC), Insertion Data for EBU Interchange (EBU 3217), and Wide Screen Signaling (WSS), used in PALplus.
In addition, certain proprietary systems are permitted for transmission in the VBI by the Federal Communications Commission (FCC), such as the Automatic Measurement of Lineups (AMOL) system of the Nielsen Corporation. Additional systems may be permitted from time to time.
SUMMARY OF THE INVENTION
The present invention relates to the representation and transmission in digital form of information that is transmitted in analog form in the Vertical Blanking Interval (VBI) of a conventional analog television waveform.
It is an object of the present invention to provide means of digitally encoding a VBI signal which are not specific to the characteristics of the particular standard governing the signal format in the analog domain, but instead depend upon certain broad characteristics of the signal. By this means a universal VBI encoding system may be implemented which is applicable to all known currently defined standards and privately defined systems, and may be extended to encode other systems not currently identified or devised.
It is a further object of the present invention to provide means of digitally encoding VBI signals which are digitally efficient, so that the VBI signals may be represented in a compressed form. By this means, the signal representation of the present invention is suitable for inclusion in a multiplex of digital signals along with compressed video and audio signals, such as are defined by MPEG2.
It is a further object of the present invention to provide means for transmitting the encoded VBI signals which are compatible with MPEG2 systems, and in particular means for transmitting encoded VBI signals which are compatible with the Universal Messaging System disclosed in U.S. application Ser. No. 08/675,558 entitled “Method for Universal Messaging and Multiplexing of Video, Audio and Data Streams”, the content of which is incorporated herein by reference in its entirety. By these means it is possible to provide certain facilities for managing and controlling VBI signals which are difficult or not possible with conventional analog systems, such as providing a choice of signals for output on particular lines of the VBI, or providing conditional access to VBI signals.
Accordingly, an encoding apparatus for encoding a television signal having video information and VBI information includes a video encoder and a VBI encoder. The video encoder encodes and compresses the video information to provide a compressed digital video stream. The VBI encoder encodes and compresses the VBI information to provide a compressed VBI information stream. A multiplexer coupled to the video encoder and the VBI encoder multiplexes the compressed digital video stream with the compressed VBI information stream to provide an output transport stream. The compressed VBI information stream is preferably a VBI message stream.
According to an aspect of the invention, the VBI encoder encodes and compresses the VBI information according to encoding parameters received from an external configuration control system, the encoding parameters being indicative of a VBI data type associated with the VBI information.
According to another aspect of the invention, the multiplexer multiplexes an externally generated VBI information stream with the compressed VBI information stream and the compressed digital video stream.
According to another aspect of the invention, for VBI information having the form of a VBI data signal, the VBI encoder includes a sampling circuit for sampling the VBI data signal to provide a sequence of luminance samples. A decimator in the VBI encoder decimates the sequence of luminance samples to provide a sequence of decimated samples that are quantized by a quantizer to provide a sequence of VBI data bits. A stream generator constructs a compressed VBI information stream from the sequence of VBI data bits. For VBI information having the form of a VBI reference signal, the VBI encoder includes means for constructing a compressed VBI information stream from the sequence of samples at a broadcast interval.
According to yet another aspect of the invention, a decoding apparatus for decoding a transport stream having a compressed digital video stream and compressed VBI information streams includes a demultiplexer that demultiplexes the transport stream to separate the compressed digital video stream and the compressed VBI information streams. A video decoder coupled to the demultiplexer decodes the compressed digital video stream to provide a decompressed video signal. A VBI decoder also coupled to the demultiplexer decodes the compressed VBI information stream to provide a VBI information signal. A combiner combines the decompressed video signal and the VBI information signal to provide an output video signal.
The term “reference signals” is used in this disclosure to mean reference signals, test signals, or both.
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p
Bennett Christopher J.
d'Oreye de Lantremange Maximilien
An Shawn S.
Hamilton Brook Smith & Reynolds P.C.
Kelley Chris
Tiernan Communications, Inc.
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