Appendix 4
The use of binary groups with film
Use of the binary groups to carry additional data as specified in SMPTE RP135-1990 is indicated by setting the flag bits as follows:
bit 43 of the type C code or bit 67 of the type B code to 0
bit 59 of the type C code or bit 83 of the type B code to 1.
As several types of additional data are specified, they cannot all be carried in one timecode frame. If the data were to be carried over a number of frames, the corruption of a single frame could result in the data being lost. The different types of data are each incorporated within a single frame, the specific type being paged by a code held within the frame.
In essence, the principle is that of a directory system, with Binary Group 1 of each timecode frame (bits 4-7 in type C, bits 28-31 in type B) identifying the type of data held in User Groups 2-7 by means of an index. Binary Group 8 carries an error detection code (checksum). The data in each of the 8 binary groups are arranged such that the lowest numbered bit in each group carries the LSB, the highest numbered bit the MSB, of a 4-bit (16 character) code. Figure A4.1 illustrates the directory index.
Table A4.1 Details of RP135-1990 Binary Groups Index.
| Index | Data | Digits reqd | Format |
| 0 | Flags | 24 | Binary |
| 1 | Date (DD:MM:YY) | 6 | BCD |
| 2 | Production no | 6 | BCD |
| 3 | Equipment ID no | 4 | 6-bit character code |
| 4 | Scene number | 4 | 6-bit character code |
| 5 | Take number | 4 | 6-bit character code |
| 6 | Roll number | 4 | 6-bit character code |
| 7-14 | Unassigned | - | - |
| 15 | Extended directory | - | - |
Figure A4.1 The SMPTE RP135-1990 binary group formats.
The index
Binary group 1 carries the index to the directory of data held in binary groups 2-7, according to Table A4.1. Each frame of film then can carry only one type of data, as specified in the index, so a sequence of several frames will be needed to carry the various possibilities of data types carried in the various directories (as we shall see when considering the Aaton timecode system) though, as stated earlier, the choice and scope of the additional data provided is a matter of discretion.
The directory
Each directory may either carry up to six discrete 4-bit items of information in the six-binary groups available, with each 4-bit item having the ability to carry either pure numeric information in BCD or hexa-decimal form; alternatively the groups may be combined to provide a greater range of values, such as a subset of the ISO 2022-1982 (ASCII) codes. The type of data being carried is indicated by an entry in the index.
Table A4.2 Detail of binary group bits flagged by Index entry '0'.
| Bit no. | Data flagged | ||
| B-format | C-format | '0' | '1' |
| 36 | 12 | Pictures | Sound |
| 37 | 13 | Sync sound/picture | No sound/picture |
| 38 | 14 | Do not print | |
| 39 | 15 | Sync speed | Not sync speed |
| 44 | 20 | Daylight photography | Night photography |
| 45 | 21 | Daylight | Tungsten light |
Table A4.3 Details of binary groups bits when carrying 6-bit characters.
| Bit numbers B-format | C-format | Weighting |
| 36, 37, 38, 39, 44, 45 | 12, 13, 14, 15, 20, 21 | Least significant character |
| 46, 47, 52, 53, 54, 55 | 22, 23, 28, 29, 30, 31 | Character |
| 60, 61, 62, 63, 68, 69 | 36, 37, 38, 39, 44, 45 | Character |
| 70, 71, 76, 77, 78, 79 | 46, 47, 52, 53, 54, 55 | Most significant character |
Entry 0
When the index is set to zero, the bits of binary groups 2-7 are set as flags to indicate the nature of the shot material according to Table A4.2. Unused bits are set to zero.
Entry 1
When the index is set to one, binary groups 2-7 carry date information in BCD format. The groups are assigned as follows:
| Group Number | Contents |
| 2 | Units of day of month |
| 3 | Tens of day of month |
| 4 | Units of month (January = 1) |
| 5 | Tens of month |
| 6 | Units of year |
| 7 | Tens of year |
The lowest-numbered bit in each group is the LSB, the highest-numbered bit the MSB. The data is displayed in increasing quantities of time, i.e. DD MM YY.
Entry 2
When the entry is set to two, binary groups 2-7 carry a 6-character numeric code identifying the production. The format is BCD.
Entry 3
When the entry is set to three, binary groups 2-7 are combined to form a 4-character alphanumeric equipment identification code (for example, to determine the camera on a multi-camera shoot). The bits in the user groups are combined together in the manner illustrated in Table A4.3. As can be seen, each character comprises six bits, so 64 separate characters are possible. These are specified in Table A4.4. The code values are identical to USS-128 (values 0-63), the barcode used in the KeyKode® system. The code is a subset of ISO 2022-1982.
Entry 4
When the entry is set to four, binary groups 2-7 are combined to form a 4-character alphanumeric scene number. Tables A4.3 and A4.4 give the details of the code format and values.
Entry 5
When the entry is set to five, binary groups 2-7 are combined to form a 4-character alphanumeric take number. Again, Tables A4.3 and A4.4 give the details of the code format and values.
Entry 6
When the entry is set to six, binary groups 2-7 are combined to form a 4-character alphanumeric roll number. Again, Tables A4.3 and A4.4 give the details of the code format and values.
Entries 7-14
At present these are unassigned. The SMPTE reserves their use.
Entry 15
When the index is set to 15, an extended directory is possible, User Group 2 becoming an extended directory index identifier for User Groups 3-7. Appendix 5 gives details of the SMPTE standards for the extended use of binary groups. Possible uses are the carrying of a second timecode, equipment control (e.g. cueing), colour correction information, remote machine control and so on.
Table A4.4 The 6-bit character code used in RP135-1990.
User Group 8
This carries error detection in the form of a checksum. It is the negative of the modulo-16 sum of groups 1-7.