1、SMPTE STANDARD SMPTE 248M-2003 Revision of ANSVSMPTE 248M-1993 for Television 19-mm Type Cue Record Digital Recording - D-2 Composite Format - and Time and Control Code Record Page 1 of 3 pages 1 Scope This standard specifies the content, format, and modulation method of the longitudinal records con
2、tained in the cue track and the time-code track in 19-mm type D-2 helical-scan cassette video recorders. Track dimensions and locations are specified in ANSVSMPTE 245M. The document applies to recorders operating in the 525-line television system with a frame frequency of 29.97 Hz. 2 Normative refer
3、ences The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to inv
4、estigate the possibility of applying the most recent edition of the standards indicated below. ANSI/SMPTE 245M-1993, Television Digital Recording - 19-mm Type D-2 Composite Format - Tape Record SMPTE 12M-1999, Television, Audio and Film - Time and Control 3 General specifications 3.1 Dimensions are
5、in the metric system. 3.2 Tests and measurements made on the tape record to check the requirements of this standard shall be made under the following atmospheric conditions unless otherwise stated: - Temperature: 20C f 1C - Relative humidity: (50 2)% - Barometric pressure: 96 kPa * 10 kPa - Tape ten
6、sion: 0.7 N * 0.05 N . 3.3 Conditioning of the tape stock before recording and testing shall be as follows: - Storage conditioning: Not less than 24 hours - Environmental: Stabilized to the conditions specified in 3.2 - Tape tension: Wound on a reel at a tension of 0.6 N to 1.5 N Copyright Q 2003 by
7、 THE SOCIEp/ OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved February 7,2003 SMPTE 248M-2003 3.4 Relative timing 3.4.1 The relationship between the start of address of the time code and the program reference point of a track with an ev
8、en-field address (count) for the video data is defined by figure 2(b) of ANSVSMPTE 245M. The start of address of the time code as recorded on the tape is defined by dimension P2, figure 2(b), of ANSVSMPTE 245M. This corresponds to the timing of the program reference point for all odd-numbered fields
9、. 3.4.2 The time and control code information shall refer to the video frame during which it is recorded. 3.4.3 Cue information shall be recorded on the tape at a point referenced to the associated video information as defined by dimension P2, figure 2(b), of ANSVSMPTE 245M (Le., cue may be up to 90
10、 TV lines early). 3.4.4 Control track servo pulse record timing is described in clause 4.1.5 of SMPTE 247M. 4 Tapespeed The basic value for tape speed is 131.700 mm/s. The tape speed tolerance is f 0.2%. 5 Cuerecord 5.1 Method of recording The signals shall be recorded using the anhysteretic (AC bia
11、s) method. 5.2 Flux level The recorded reference audio level shall correspond to an rms magnetic short circuit flux level of 80 nWb/m f 5 nWb/m of track width at 1 O00 Hz. 5.3 Recorded flux characteristics When a tape record is recorded from a constant voltage level applied to the input terminals of
12、 the recording system, the short circuit flux level on the record versus frequency shall be given by the following equation: I I where Lo is the relative flux level; f is the frequency at which the response is calculated; and Fh is the upper transition frequency, 10.8 kHz. (This corresponds to a tim
13、e constant of 15 microseconds.) 6 Time and control code record 6.1 Method of recording The signals shall be recorded using the anhysteretic (AC bias) recording method. Page 2 of 3 pages SMPTE 248M-2003 6.2 Flux level The recorded peak-to-peak flux shall correspond to a magnetic short circuit flux le
14、vel of 250 nWb/m f 20 nWb/m of track width. 6.3 Recorded flux characteristics When a tape record is recorded from a constant voltage level applied to the input terminals of the recording system, the short circuit flux level on the record versus frequency shall remain constant. 6.4 Signal The signal
15、recorded on this track shall be in accordance with SMPTE 12M. Annex A (informative) Bibliography ANSI/SMPTE 226M-1996, Television Digital Recording - 19-mm Tape Cassettes SMPTE 246M-2003, Television Digital Recording - 19-mm Type 0-2 Composite Format - Magnetic Tape SMPTE 247M-2003, Television Digit
16、al Recording - 19-mm Type D-2 Composite Format - Helical Data and Control Records SMPTE EG 20-1997, Tape Transport Geometry Parameters for 19-mm Type D-2 Composite Format for Television Digital Recording SMPTE EG 21-1997, Nomenclature for Television Digital Recording of 19-mm Type D-1 Component and Type D-2 Composite Formats ITU-R BT.470-6 (1 1/98), Conventional Television Systems Page 3 of 3 pages
