1、 1 Scope This practice specifies digital code formats and modulation methods for motion-picture film to be used for timing, control, editing, and synchronization purposes. This practice also specifies the relationship of the code to the motion-picture frame. The codes described in this practice are
2、similar to the continuous code described in SMPTE 12M. There are two types of codes described in this practice. The first type, type C, is a continuous code which is very similar to the continuous code specified in SMPTE 12M. This type of code can be used in situations where the film is moving conti
3、nuously at the time of both recording and reproduction. The second type of code, type B, is a noncontinuous, block-type code, composed of blocks of data, each complete in itself, with gaps between the blocks. It is designed so that the code may be recorded and played back on equipment with intermitt
4、ent film motion but still be decoded with the same type of electronic equipment used to read the type C or continuous time code. The codes described in this practice can be used at various frame rates, the ones currently of interest being 24, 25, and 30 frames per second. 2 Normative references The
5、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 standards are subject to revision, and parties to agreements based on this practice are encouraged to investigate t
6、he possibility of applying the most recent edition of the standards indicated below. ISO/IEC 2022:1994, Information Technology Character Code Structure and Extension Techniques SMPTE RP 114-1994 (R1999), Dimensions of Photographic Control and Data Record on 16-mm Motion-Picture Film SMPTE RP 115-199
7、7, Dimensions of Photographic Control and Data Record on 35-mm Motion-Picture Release Prints SMPTE RP 116-2000, Dimensions of Photographic Control and Data Record on 35-mm Motion-Picture Camera Negatives SMPTE RP 135-1999, Use of Binary User Groups in Motion-Picture Time and Control Codes Page 1 of
8、8 pages RP 136-2004 Revision of RP 136-1999 Copyright 2004 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved November 8, 2004 SMPTE RECOMMENDED PRACTICE Time and Control Codes for 24, 25 or 30 Frame-Per-Second Motion-Pictu
9、re Systems RP 136-2004 Page 2 of 8 pages 3 Modulation method The modulation method shall be such that a transition occurs at the beginning of every bit period. One is represented by a second transition one half a bit period from the start of the bit. Zero is represented when there is no transition w
10、ithin the bit period. 4 Code formats Two code formats are described: type C and type B. Clauses 4.1 and 4.2 describe the unique characteristics of the two code types. The other clauses, 4.3 and 4.4, apply to both code types. 4.1 Type C code format 4.1.1 Each motion-picture frame shall be defined by
11、a unique and complete address. 4.1.2 The frames shall be numbered successively 0 through 23, 24, or 29, corresponding to the frame rate being used. 4.1.3 Each address shall consist of 80 bits numbered 0 through 79. 4.1.4 The bits shall be assigned as shown in the appropriate columns of figure 1 and
12、table 1. 4.1.5 Timing of the address The address shall start at the clock edge before the first address bit (bit zero). The bits shall be evenly spaced throughout the address period, and they shall fully occupy the address period, which is one frame. Consequently, the bit rate shall be 80 times the
13、frame rate in frames per second. 4.1.6 The start of the address, i.e., the clock edge before the first bit, shall coincide with the frameline at the beginning of the image to which the address refers. The tolerance of this location is +0% (in direction of film travel) and -50% of a frame length (in
14、the other direction). (Thus, the start of the address may lie anywhere in the top half of the frame with the preferred position at the frameline.) (See figure 2.) 4.2 Type B code format 4.2.1 Each motion-picture frame shall be identified by a unique and complete address. 4.2.2 The frames shall be nu
15、mbered successively 0 through 23, 24, or 29, corresponding to the frame rate being used. 4.2.3 Each address shall consist of 112 bits numbered 0 through 111. 4.2.4 The bits shall be assigned as shown in the appropriate columns of figure 1 and in table 1. 4.2.5 Boundaries of the address The block of
16、data for a single frame may be recorded anywhere within that frame except that no part of the block may occupy the region extending from the frameline to 5% of a frame length on either side of it. This region is thus a gap in the data which has a minimum length of 10% of a frame length (see figure 3
17、). 4.2.6 Bit length The length of any one bit shall not differ by more than 5% from the length of either adjacent bit. In addition, the length of no bit shall be so short as to make the recording and reproduction of the data, using practical equipment, unreliable; and the length of no series of bits
18、 may cause the total length of 112 bits to exceed 90% of frame length. RP 136-2004 Page 3 of 8 pages BIT NO. TYPE C BIT NO. TYPE B BIT VALUE DESCRIPTION NOTES 0 1 2 3 4 5 6 7 0 1 0 1 0 1 0 1 TIMING BITS START FOR TYPE B IS CLOCK EDGE BETWEEN BIT 111 AND BIT 0 8 9 10 11 12 13 14 15 16 17 18 19 20 21
19、22 23 0 0 1 1 1 1 1 1 1 1 1 1 1 1 0 1 SYNC WORD START FOR TYPE C IS CLOCK EDGE BETWEEN BIT 79 AND BIT 0 0 1 2 3 24 25 26 27 1 FRAME UNITS 2 4 8 4 5 6 7 28 29 30 31 1ST BINARY GROUP 8 9 32 33 10 FRAMES TENS 20 10 34 DROP FRAME FLAG 11 35 COLOR FRAME FLAG 12 13 14 15 36 37 38 39 2ND BINARY GROUP 16 17
20、 18 19 40 41 42 43 1 SECONDS UNIT 2 4 8 20 21 22 23 44 45 46 47 3RD BINARY GROUP 24 25 26 48 49 50 10 SECONDS TENS 20 40 27 51 BI-PHASE MARK PHASE CORRECTION BIT 28 29 30 31 52 53 54 55 4TH BINARY GROUP TYPE C TIME CODE 80 BITS PER FRAME 32 USER BINARY SPARE BITS 16 SYNC 31 ASSIGNED ADDRESS 1 UNASSI
21、GNED ADDRESS UNASSIGNED BIT IS ZERO 32 33 34 35 56 57 58 59 1 MINUTES UNITS 2 4 8 36 37 38 39 60 61 62 63 5TH BINARY GROUP 40 41 42 64 65 66 10 MINUTES TENS 20 40 43 67 BINARY GROUP FLAG BIT 44 45 46 47 68 69 70 71 6TH BINARY GROUP 48 49 50 51 72 73 74 75 1 HOURS UNITS 2 4 8 52 53 54 55 76 77 78 79
22、7THBINARY GROUP 56 57 80 81 10 HOURS TENS 20 TYPE B TIME CODE 112 BITS PER FRAME 32 USER BINARY SPARE BITS 48 SYNC 31 ASSIGNED ADDRESS 1 UNASSIGNED ADDRESS UNASSIGNED BIT IS ZERO 58 82 UNASSIGNED ADDRESS BIT 59 83 BINARY GROUP FLAG BIT 60 61 62 63 84 85 86 87 8TH BINARY GROUP RP 136-2004 Page 4 of 8
23、 pages BIT NO. TYPE C BIT NO. TYPE B BIT VALUE DESCRIPTION NOTES 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 0 0 1 1 1 1 1 1 1 1 1 1 1 1 0 1 SYNC WORD 104 105 106 107 108 109 110 1 0 1 0 1 0 1 TIMING BITS Figure 1 Bit assignment Table 1 Assignm
24、ent of bits Bits type C code Bits type B code 1) 1) 1) 1) 1) 1)0-3 4-7 8-9 10 11 12-15 16-19 20-23 24-26 27 28-31 32-35 36-39 40-42 43 44-47 48-51 52-55 56-57 58 59 60-63 64-79 64-65 66-77 78 79 1) 0-7 8-23 8-9 10-21 22 23 24-27 28-31 32-33 34 35 36-39 40-43 44-47 48-50 51 52-55 56-59 60-63 64-66 67
25、 68-71 72-75 76-79 80-81 82 83 84-87 88-103 88-89 90-101 102 103 104-111 Alternating zero, one pattern Synchronizing word Fixed zero Fixed one Fixed zero Fixed one Units of frame First binary group Tens of frames Drop frame flag (see 4.4) Color frame flag (see 4.4) Second binary group Units of secon
26、ds Third binary group Tens of seconds Bi-phase mark phase correction bit (see 4.4) Fourth binary group Units of minutes Fifth binary group Tens of minutes Binary group flag bit (see 4.4) Sixth binary group Units of hours Seventh binary group Tens of hours Unassigned address bit (0 until assigned by
27、the SMPTE) Binary group flag bit (see 4.4) Eighth binary group Synchronizing word Fixed zero Fixed one Fixed zero Fixed one Alternating one, zero pattern 1)These bits do not exist in the type C code. RP 136-2004 Page 5 of 8 pages Figure 2 Type C code Figure 3 Type B code NOTE Figures 2 and 3 illustr
28、ate the preferred longitudinal placement of a frame of time code relative to the picture frame. Thy are not intended to identify the track position on the film. The figures apply to all film formats, even though 35-mm is shown. RP 136-2004 Page 6 of 8 pages 4.2.7 Data in the gap In order to reduce t
29、he dc content of the signal, a repetitive pattern of zeros and ones shall be recorded in as much of the gap area (the frameline region defined in 4.2.5) as is practical. In no case may this region contain a sync word nor may these bits, together with the second sync word of the previous frame and th
30、e first sync word of the following frame, be decodable as a valid time code word. The bit length tolerance in 4.2.6 does not apply to data in the gap. 4.3 Use of binary groups The binary groups are intended for storage of data by the users, and the 32 bits within the 8 groups may be assigned in any
31、fashion without restrictions if the character set used for the data insertion is not specified and the binary group flag bits, Nos. 43 and 59, both are zero. The binary group flag bits 43 and 59 (67 and 83 for type B code) shall be set according to the following truth table: Bit 43 (67) Bit 59 (83)
32、Character set not specified 0 0 Character set as defined in ISO/IEC 2022 1 0 Data and checksum as defined in SMPTE RP 135 0 1 Unassigned 1 1 The unassigned state of the truth table cannot be used and its assignment is reserved to the SMPTE. 4.4 Assigned and unassigned address bits Six bits are reser
33、ved within the address groups, 4 for identifying operational modes when this type of code is used for television systems (see SMPTE 12M), 1 for bi-phase correction, and 1 unassigned but reserved for future assignment and defined as zero until further specified by the SMPTE. Bit 10, type C code; bit
34、34, type B code Drop frame flag. If certain numbers are being dropped to resolve the difference between real time and color time, as defined in 5.2.2, a 1 shall be recorded. Bit 11, type C code; bit 35, type B code Color frame flag. If color frame identification has been intentionally applied, a 1 s
35、hall be recorded. Bit 27, type C code; bit 51, type B code Bi-phase mark phase correction. Shall be put in a state so that every 80- or 112-bit word will contain an even number of logic zeros. This requirement results in the following truth table for bit 27 (51): Number of logic zeros in bits 0 to 2
36、6 Type C Type B (24 to 50), and bits 28 to 63 (52 to 87) bit 27 bit 51 Odd 1 0 Even 0 1 Bits 43, 59, type C code; bits 67, 83 type B code Binary group flag bits. These two bits shall be set in accordance with the truth table specified in 4.3. RP 136-2004 Page 7 of 8 pages Bit 58, type C code; bit 82
37、, type B code Unassigned address. 0 until assigned by SMPTE. 5 Time discrepancies 5.1 When the film on which the time code is recorded is transferred from or will be transferred to television, or is otherwise used in conjunction with a 525-line/60-field television system, there may be a need to use
38、the drop frame counting mode. This clause presents pertinent definitions. 5.1.1 Real time is defined as the time elapsed during the scanning of 60 fields (or any multiple thereof) in an ideal television system at a vertical field rate of exactly 60 fields per second. 5.1.2 Color time is defined as t
39、he time elapsed during the scanning of 60 fields (or any multiple thereof) in a color television system at a vertical field rate of approximately 59.94 fields per second. 5.2 Because the vertical field rate of a color signal is approximately 59.94 fields per second, straightforward counting at 30 fr
40、ames per second (60 fields per second) will yield an error of +108 frames (+216 fields), equivalent to +3.6 seconds timing error, in one hour of running time. For correction of this time discrepancy, two methods of operation are allowed: 5.2.1 Nondrop frame uncompensated mode (30-frame code only). D
41、uring a continuous recording, no numbers shall be omitted from the chain of addresses. Each address shall be increased by 1 frame over the frame number immediately preceding it. When this mode is used, bit No. 10 (34) of each address shall be a 0 as specified in 4.4. 5.2.2 Drop frame compensated mod
42、e (30-frame code only). To resolve the color time error, the first two frame numbers (0, 1) at the start of each minute, except minutes 0, 10, 20, 30, 40, and 50, shall be omitted from the count. When this mode is used, bit No. 10 (34) of each address shall be a 1 as specified in 4.4. 6 Structure of
43、 the address bits The basic structure of the address is based on the Binary Coded Decimal (BCD) system. Because the count, in some cases, does not rise to 9, conservation of bits is achieved because 4 bits are not needed as in an ordinary BCD code. (Bits shown in parentheses are for type B code.) 6.
44、1 Units frames. Bits 0-3 (24-27) 4 bit BCD arranged 1, 2, 4, 8. Count 0-9. 6.2 Tens frames. Bits 8-9 (32-33) 2 bit BCD arranged 1, 2. Count 0-2. 6.3 Units seconds. Bits 16-19 (40-43) 4 bit BCD arranged 1, 2, 4, 8. Count 0-9. 6.4 Tens seconds. Bits 24-26 (48-50) 3 bit BCD arranged 1, 2, 4. Count 0-5.
45、 6.5 Units minutes. Bits 32-35 (56-59) 4 bit BCD arranged 1, 2, 4, 8. Count 0-9. 6.6 Tens minutes. Bits 40-42 (64-66) 3 bit BCD arranged 1, 2, 4. Count 0-5. 6.7 Units hours. Bits 48-51 (72-75) 4 bit BCD arranged 1, 2, 4, 8. Count 0-9. 6.8 Tens hours. Bits 56-57 (80-81) 2 bit BCD arranged 1, 2. Count
46、 0-2. NOTE The 24-hour clock system is used; 2:00 p.m. is 14 hours, 0 minutes. RP 136-2004 Page 8 of 8 pages 7 Position of the address on motion-picture film 7.1 Optical tracks 7.1.1 35-mm release print film The address shall be recorded in the data track whose location is specified in SMPTE RP 115.
47、 7.1.2 35-mm camera film The address shall be recorded in the data track whose location is specified in SMPTE RP 116. 7.1.3 16-mm film The address shall be recorded in the data track whose location is specified in SMPTE RP 114. 8 Addresses on motion-picture prints When the time code is used on final
48、 prints, the time code of the picture start frame shall be 01 hours, 00 minutes, 00 seconds, 00 frames. All frames on the reel prior to the picture start frame shall each have the time code 01 hours, 00 minutes, 00 seconds, 00 frames. If the film is longer than one reel, the picture start frame and
49、all preceding frames on the second reel shall be 02 hours, 00 minutes, 00 seconds, 00 frames. Successive reels shall be numbered likewise, with the number of hours increasing sequentially and the minutes, seconds, and frames being zero for the picture start frame. The picture start frame referred to above precedes the first frame to be projected by exactly eight seconds, as identified in SMPTE 55. Annex A (informative) Bibliography SMPTE 55-2000, Motion-Picture Film 35- an
