IEC 60461 pdf download – Code temporel de commande pour les magnétoscopes Time and control code for video tape recorders

IEC 60461 pdf download – Code temporel de commande pour les magnétoscopes Time and control code for video tape recorders
1 scope
This International Standard specifies a digital time and control code for use in television,film,and accompanying audio systems operating at 30,25,and 24 frames per second.
Clauses 4,5, and 6 specify the manner in which time is represented in frame-based systems.Clause 7 describes the structure of the time address and control bits of the code, and setsguidelines for storage of user data in the code.Clause 8 specifies the modulation method andinterface characteristics of a linear time code (LTC) source.Clause 9 specifies the modulationmethod for inserting the code into the vertical interval of a television signal. Clause 10summarizes the relationship between the two forms of time and control code.
2Normative references
The following normative documents contain provisions which，through reference in this text,constitute provisions of this International Standard. For dated references,subsequentamendments to,or revisions of，any of these publications do not apply. However，parties toagreements based on this International Standard are encouraged to investigate the possibilityof applying the most recent editions of the normative documents indicated below. For undatedreferences， the latest edition of the normative document referred to applies. Members of lECand lso maintain registers of currently valid International Standards.
ISO/IEC 646:1991，Information technology – ISo 7-bit coded character set for informationinterchange
ISO/IEC 2022:1994,Information technology – Character code structure and extensiontechniques
SMPTE170M:1999，Television – Composite Analog Video Signal – NTSC for StudioApplications
SMPTE 240M:1995,Television – Signal Parameters – 1125-Line High-Definition ProductionSystems
SMPTE 258M:1993，Television – Transfer of Edit Decision Lists
SMPTE 262M:1995,Television，Audio and Film – Binary Groups of Time and Control Codes -Storage and Transmission of Data
SMPTE 309M: Television – Transmission of Date and Time Zone Information in Binary Groupsof Time and Control Code
SMPTE RP164:1996,Location of Vertical Interval Time CodeITU-R BT.470-6:1994,Conventional Television Systems
3Definitions
For the purpose of this International Standard, the following definitions apply:
3.1
linear time code (LTC)
linear time code modulation system (previously referred to as the longitudinal track applicationof time and control code)
3.2
vertical interval time code (vITc)
modulation system used to insert the time code signal in the vertical blanking interval of atelevision signal
3.3
source
any device which generates a time and control code signal, or regenerates a time and controlcode signal from a recorded medium or transmission channel
An original source refers specifically to the device which is generating the time and controlcode signal.
3.4
binary coded decimal(BCD) system
means for encoding decimal numbers as groups of binary bits.Each decimal digit (0-9) isrepresented by a unique four-bit code. The four bits are weighted with the digit’s decimalweight multiplied by successive powers of two
NOTE For example, the bit weights for a “units” digit would be 1 x 2°.1 × 2′, 1 x 2, and 1 x 2 , while the bitweights for a “tens” digit would be 10 x 2°,10 x 21,10 x 22 , and 10 x 23.
4Time representation in 30-frame systems
4.1Definitions of real time and NTsC time
4.1.1 In a system running at a frame rate of 30 frames per second, exactly one second of realtime elapses during the scanning of 30 frames.An example of such a system is an 1125/60high-definition system.
4.1.2 ln an NTSC television system running at a vertical field rate of 60/1,001 fields persecond (= 59,94 Hz), one second of NTsC time elapses during the scanning of 60 televisionfields or 30 television frames. Because of the difference in vertical scanning rates,therelationship between real time and NTSC time is:
1 s NTsC time = 1,001 s REAL time
4.2Time address of a frame
Each frame shall be identified by a unique and complete address consisting of an hour, minute,second, and frame number.Refer to SMPTE 258M for standard formats used to display frame-based time.