IEC 61834-7 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)
This part of IEC 61834 is an extension to the SD specification (SD mode) and covers the features necessary for the recording and reproduction of EDTV2 signals. While all DVCRs must have the capability of recording and/or playback in SD (SP) mode, this extension is optional. For this part 7, the data track structure of a track is defined by APT = 000b which consists of four areas as described in 4.3.2 of IEC 61834-1, and AP1 = AP2 = AP3 = 000b. NOTE EDTV2 signal format is described in the specification: BTA T-1004-1995: Video signal interfaces for EDTV2 studio equipment.
1.2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of IEC 61834. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of IEC 61834 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 61834-1:1998, 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 1: General specifications IEC 61834-2:1998, 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 2: SD format for 525-60 and 625-50 systems IEC 61834-4:1998, 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 4: Pack header table and contents IEC 61883-1:1998, Consumer audio/video equipment – Digital interface – Part 1: General
7 Video signal processing
7.1 Introduction The helper signals are demodulated. They are handled by the Y channel. After certain processing, EDTV2 ID bits are rewritten and stored in the VAUX TR pack. 7.2 Error correction code Same as IEC 61834-2. 7.3 Randomization pattern Same as IEC 61834-2. 7.4 Video structure 7.4.1 Helper signals Recording The vertical helper signal (VT/VH) is demodulated on the Q phase of the colour subcarrier with the adaptive set-up level preserved. The amplitude of the demodulated vertical helper signal is multiplied by 0,5, a DC level of 16 is added and it is then inserted into the Y channel (refer to figures 1 and 2). Recording of the vertical helper signal is optional. The horizontal helper signal (HH) shall be decoded and added to the luminance signal. The EDTV2 signal may optionally be recorded without the helpers (helper killer mode). In some situations the helper killer mode may optionally be used, in which case b8 to b11 in the EDTV2 ID should be set to “0”. In lines 53, 54, 231, 232 and also lines 316, 493, 494, 495, the luminance and chrominance levels may optionally be set to 32 and 128 respectively (refer to figure 3). Playback The DC level and the amplitude of the reproduced vertical helper signal is reconstructed to its original state (refer to figure 4). 7.4.2 EDTV2 ID bits EDTV2 ID (b1 to b24) are rewritten and stored in the VAUX TR pack as shown in table 1 (refer to 7.11).EDTV2 ID (b1 to b24) in lines 22 and 285 are encoded according to the contents of the VAUX TR pack and the confirmation signal (b25 to b27) in lines 22 and 285 is reconstructed to accord with EDTV2 specifications. 7.4.3 Sampling structure Same as 525-60 system in 7.4.1 of IEC 61834-2.