Television – Image signal processing circuitry specific to television – Switching
Patent
1995-11-28
1998-05-19
Kostak, Victor R.
Television
Image signal processing circuitry specific to television
Switching
348706, H04N 5268
Patent
active
057542554
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a digital switcher adapted to select a desired digital signal from a plurality of digital signal inputs to output the digital signal thus selected.
BACKGROUND ART
Generally, in broadcasting stations or production houses, etc., transmission and reception of digital video signals are carried out between a large number of video equipments through so called effect switchers which are digital video switchers for selecting a desired digital video signal from a plurality of digital video signal inputs to implement mix processing or wipe processing, etc. thereto.
As an interface for carrying out transmission of digital video signals, e.g., Society of Motion Picture and Television Engineers (SMPTE) of U.S.A. standardizes, as interface for digital video signals of the bit parallel system, a format for carrying out transmission of parallel digital video signals of 10 bits with respect to component signal at SMPTE125M.
Further, as an interface for digital video signals of the bit serial system which permits long distance transmission of video signals by a single cable, e.g., in SMPTE, there is standardized SMPTE259M in which scrambled NRZI (Non Return to Zero Inverted) codes are employed as channel codes along with component signals and composite signals. Also in the International Radio Consultative Committee (CCIR), components signals are standardized as 656 III. Also in the European Broadcasting Union (EBU), components signals are standardized as Tech 3267.
In the format of the above-mentioned SMPTE259M, an approach is employed to bit-serially convert parallel digital video signals of 10 bits to carry out transmission of serial digital video signals as scrambled NRZI code. Moreover, with respect to the line monitoring, in the scrambled NRZI code, Error Detection and Handling (EDH) system is standardized, wherein there is employed a technique for carrying out transmission of digital video signals in which Ancillary data such as parity or check sum for detecting error produced in equipments within the system or interface, etc., or Cyclic Redundancy Check Code (CRCC), etc. are inserted at specific lines of the vertical blanking period. Namely, for monitoring transmission error, e.g., CRC code of data of full fields including ancillary data between one fields, CRC code of data consisting of only active pictures between one fields, and CRC code consisting of only ancillary data are calculated on the transmitting side, and these CRC codes are transmitted as EDH packet. As the generator polynomial (generating function) of the CRC code,
Outline of the format of Serial Digital Interface (SDI) standardized by the above-mentioned SMPTE259M is shown in the following table 1.
TABLE 1 ______________________________________
Outline of SMPTE259M
ITEM COMPONENT COMPOSITE
______________________________________
TRANSMISSION RATE
270.0 143.18
(Mb/s)
CHANNEL CODING
SCRAMBLED NRZI
X = (X.sup.9 + X.sup.4 + 1)(X + 1)
SERIAL SYNC SIGNAL
3FF, 000, 000
SIGNAL AMPLITUDE
800 mV .+-. 10% (750 ohms
TERMINATION)
NO. OF AUDIO 8 ch 4 ch
CHANNELS
______________________________________
Meanwhile, while approach is employed to insert ancillary data for error correction into a digital video signal to carry out serial digital transmission, thereby making it possible to monitor, by equipments of the receiving side, generating state of error in equipments of the transmitting side or transmission path, in broadcasting stations or production houses where a large number of video equipments are used in combination, in the case where error detectors for carrying our error detection on the basis of the ancillary data are provided every equipments, not only scale of the hardware becomes large, but also it is difficult to precisely carry out management of error generating state in respective equipments or transmission path.
In view of actual circumstances of the prior arts as described above, an object of this invention is to have an ability to precisely carry out management of gen
REFERENCES:
patent: 4774570 (1988-09-01), Araki
patent: 5276445 (1994-01-01), Mita et al.
Frommer William S.
Kostak Victor R.
Sony Corporation
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