1、SMPTE RECOMMENDED PRACTICE RP 93-1 999 Revision of RP 93-1994 Requirements for Recording American National Standard Time and Control Code on i-in Type B Helical-Scan Video Tape Recorders 1 Scope This practice specifies the recorded signal and the conditions for recording the time and control code on
2、 1 -in type 6 helical-scan video tape recorders as specified in ANSKMPTE 12M. Page 1 of 2 pages SMPTE RP 83-1 996, Specifications of Tracking Control Record for 1-in Type B Helical-Scan Television Analog Recording SMPTE RP 84-1 996, Reference Carrier Frequencies and Preemphasis Characteristics for 1
3、-in Type B Helical-Scan Television Analog Recording 3 Position of code on video tape 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this practice. At the time of publication, the editions indicated were valid. All sta
4、ndards are subject to revision, and parties to agreements based on this practice are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. ANSVSMPTE 12M-1995, Television, Audio and Film - Time and Control Code SMPTE 15M-1998, Television Analo
5、g Record- ing - 1-in Type B Helical Scan - Basic Sys- tem Parameters SMPTE 16M-1998, Television Analog Record- ing - 1-in Type B Helical Scan - Records SMPTE 17M-1998, Television Analog Record- ing - 1 -in Type B Helical Scan - Frequency Response and Operating Level 3.1 The code, if used, shall be r
6、ecorded on the audio 3 track. 3.2 The start of the address for original recording shall be as specified in ANSI/SMPTE 12M. 3.3 The position of the address start point along the tape is determined by the position of the appropriate audio head gap. 4 Recorded signal 4.1 The input waveform of the recor
7、der for origi- nal time and control code recording shall be as specified in ANSI/SMPTE 12M. 4.2 The response of the recording channel shall be as specified in ANSVSMPTE 17M. 4.3 The amplitude of the recorded signal shall be such as to produce a peak-to-peak short circuit recorded flux level on the t
8、ape of at least 185 nWb/m of track width. Copyright O 1999 by the SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved April 22, 1999 I STD-SMPTE RP 93-ENGL 3977 W 8357403 O003602 502 = RP 93-1999 Annex A (informative) Additional da
9、ta A.1 Flux level mecurements Means for measuring the short-circuit flux level on magnetic recordings usually are not available to users of audio and video tape recorders. The values recommended in this practice may be established by use of reference tapes. Such tapes usually contain a sine-wave ref
10、erence level recording on each audio track whose rms short-circuit flux level is as specified for the format being used. Usually the recorder is adjusted to record the same level that exists on the refer- ence tape when its volume meter reads O vu. If the recording level of the code then is adjusted
11、 so that the volume indicator reads O vu, the recorded code will have the required peak- to-peak flux level specified in 4.3. Measurements should be made with a standard volume indicator (vu meter), as speci- fied in ANSIIIEEE 152. Although the ballistics of the meter are of little importance with r
12、espect to the code, the use of a full-wave rectifier and the approximate average reading characteristic of the volume indicator are essential to the accuracy of the procedure. A.2 Dub recordings A.2.1 The preferred method of producing time and control code dubs is by insertion of a slaved time code
13、generator in Annex B (informative) Bibliography the video and time code signal paths between reproducer and recorder to ensure compliance with all sections of ANSIISMPTE 12M and the section of this practice for original recordings. When using this method, the user-bit information, if any, may be del
14、ayed by two or more frames due to the length of a complete code group and the mechani- cal tolerance of audio head-gap location specified. A.2.2 Other acceptable methods of producing time and control code dubs are: A.2.2.1 Reclock and reshape the time code waveform to meet ANSIISMPTE 12M. The result
15、ing waveform will not comply with ANSVSMPTE 12M, thereby allowing buildup of video-to-address timing errors on multiple-generation dubs. A.2.2.2 Reshape the time code waveform to meet ANSUSMPTE 12M. Video-to-address timing errors and waveform transition jitter will build up on multigeneration dubs. A.2.2.3 Provide no special time code signal processing. The usefulness of dubs will be limited. ANSIIIEEE 152-1 992, Audio Program Level Measurement Page 2 of 2 pages
