IEC 61834-8 pdf download – Recording – Helical-scan digital video cassette recording system using 6,35 mm magnetic tape for consumer use (525-60, 625-50, 1125-60 and 1250-50 systems) Part 8: PALplus format for the 625-50 system
1General1.1scope
This part of lEC 61834 is an extension of the SD specification (SD mode) and covers thefeatures necessary to enable a DVCR to record and reproduce PALplus signals.
While all DVCRs must have the capability of recording and/or playback in SD (SP) mode,PALplus capability is optional.
For this Part 8, the data structure of a track is defined by APT = 000b which consists of fourareas as described in 4.3.2 in lEC 61834-1 and AP1 = AP2 = AP3 = 000b.
There are two methods for recording the PALplus signal on a DVCR:
– method 1: record the partially encoded PALplus signal;
– method 2: record the completely decoded PALplus signal.
This part is concerned with “Method 1” (baseband helper recording) as this requires anextension to the DVCR SD specification lEC61834-2.
For “Method 2” the DVCR is equipped with a built-in PALplus decoder and the SD specificationlEC 61834-2 applies unchanged.
1.2 Normative references
The following normative documents contain provisions which，through reference in this text,constitute provisions of this part of lEC 61834.For dated references, subsequent amendmentsto,or revisions of，any of these publications do not apply. However，parties to agreementsbased on this part of IEC 61834 are encouraged to investigate the possibility of applying themost recent editions of the normative documents indicated below.For undated references, thelatest edition of the normative document referred to applies. Members of lEC and IS0 maintainregisters of currently valid lnternational Standards.
IEC 61834-1:1998,Recording – Helical-scan digital video cassette recording system using6,35 mm magnetic tape for consumer use (525-60,625-50，1125-60 and 1250-50 systems)-Part 1: General specifications
IEC 61834-2:1998,Recording – Helical-scan digital video cassette recording system using6,35 mm magnetic tape for consumer use (525-60,625-50，1125-60 and 1250-50 systems) -Part 2:sD format for 525-60 and 625-50 systems
IEC 61883-1:1998,Consumer audiolvideo equipment – Digital interface – Part 1:GeneralIEC 61883-2:1998,Consumer audio/video equipment – Digital interface – Part 2:SD-DVCRdata transmission
1.3Definitions, symbols and abbreviations
BCH code Bose-Chaudhuri-Hocquenghem code,one of the well-known error correction
codes
CGMs
Copy Generation Management System
DCT
Discrete Cosine Transform
DvCR
Digital Video Cassette Recorder
ITU
lnternational Telecommunication Union
MACP
Motion Adaptive Colour Plus
SDTR
Standard Definition Transparent
VAUX
Video Auxiliary Data
vLc
Variable Length Coding
wss
wide Screen Signalling
Helper
The extra signal coded into the letterbox black bars to restore full luminance
signal
vertical resolution
1.4Test conditions and environmentSame as lEC 61834-2.
2Helical recordings
Same as 625-50 system in lEC 61834-2.
3Programme track data arrangementSame as 625-50 system in lEC 61834-2.
4Audio interface
Same as lEC 61834-2.
5 Video interface
The principal mode of interface is analogue. The analogue video signal shall be convertedaccording to 7.4.1 in IEC61834-2.
The video signal may also be input and output digitally in a bit-serial form. When the bit-serialinterface for this standard is prepared, the data structure for transmission shall conform toclause 11.
For details of the standard digital interface, refer to lEC 61883-1 and IEC 61883-2.
6 Audio signal processing
Same as 625-50 system in lEC 61834-2.
7 Video signal processing
7.1 lntroduction
The helper signals are demodulated. After certain processing，they are treated in the Ychannel.The wss signalling bits are rewritten and stored in the VAUX TR pack.The WHITELEVEL REFERENCE is also written in the VAUX TR pack.
7.2 Error correction code
Same as lEC 61834-2.
7.3 Randomization patternSame as lEC 61834-2.
7.4Video structure7.4.1 Helper signalsa) Recording
The helper signal and the helper reference burst in line 23 are demodulated on the U (B-Y)phase of the colour subcarrier and processed as a Y signal before compression (refer tofigure 1).
A constant DC level is added to the demodulated helper signal and the helper reference burstsignal, before recording (refer to figure 2). The “helper killer” block can be incorporated toenable PALplus recording without the helper (helper killer mode). The helper killer mode mayoptionally be used in some situations.
ln helper killer mode, b6 is set to “”o”.
Bit b5 should always be set to “o”，irrespective of the presence of a MACP decoder beforerecording.
Optionally,the luminance level may be set to 32 and chrominance levels to 128 in lines 60,61,62 and lines 372,373,374 (refer to figure 3).
b) Playback
The reproduced helper signal and the helper reference burst in line 23，after DC levelcorrection, are modulated on the u (B-Y) phase of the colour subcarrier, and appear at the YICoutput (s-terminal) as the C signal (refer to figure 4).
IEC 61834-8 pdf download – Recording – Helical-scan digital video cassette recording system using 6,35 mm magnetic tape for consumer use (525-60, 625-50, 1125-60 and 1250-50 systems) Part 8: PALplus format for the 625-50 system
