1、SMPTE RP*Lb5 94 m 8357401 OOOL7LO 785 m SMPTE RECOMMENDED PRACTICE Error Detection Checkwords and RP 165-1 994 Revision of RP 165-1993 Status Flags for Use in Bit-Serial Digital Interfaces for Television 1 Scope 1.1 This practice, also known as the error detec- tion and handling (EDH) system, descri
2、bes the generation of error detection checkwords and related status flags to be used optionally in conjunction with the serial digital interface for system M (525/59.94) and systems 8, G, H, and I (625/50) digital television equipment operating with either 13.5-MHz or 18-MHz sampled 4:2:2 component
3、digital signals or 4fsc composite digital signals. Although it is preferred that this error-checking method be used in all serial transmitters and receivers, it is recognized that some equipment must minimize complexity. Additionally, there is nothing in this practice which should preclude its use i
4、n a parallel digital interface for 4:2:2 component digital signals. 1.2 Two checkwords are defined: one based on a field of active picture samples and the other on a full field of samples. This two-word approach provides continuing error detection for the active picture when the digital signal has p
5、assed through processing equipment that has changed data outside the active picture area without re- calculating the full-field checkword. 1.3 Three sets of flags are provided to feed for- ward information regarding detected errors to help facilitate identification of faulty equipment and the type o
6、f fault. One set of flags is associ- ated with each of the two field related check- words. A third set of flags is used to provide similar information based on evaiuating all of the ancillary data checksums within a field. Imple- mentation of these flags is not a requirement of this practice. Page 1
7、 of 6 pages 1.4 The checkwords and flags are combined in an error detection data packet which is included as ancillary data in the serial digital signal. At the receiver, a recalculation of check- words may be compared to the error detection data packet information to determine if a trans- mission e
8、rror occurred. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this practice. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this p
9、ractice are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. SMPTE RP 168-1993, Definition of Vertical Interval Switching Point for Synchronous Video Switching 3 Location of checkwords, flags, identi- fication number, and included samples
10、 3.1 Location of checkwords, flags, and identifica- tion number Digital data packets containing the calculated check- words, error information flags, and identification num- ber are located in the ancillary data area of,the vertical interval in a manner to complement the recommended practice of sour
11、ce switching. Loca- tions are shown graphically in figure l and specified in table 1 for 52W59.94 systems and table 2 for 625/50 systems. For composite signals, the error detection data packet is located in the ancillary data area of the first horizontal pulse occurring in the line prior to the reco
12、mmended vertical interval switching point of each field. For component signals, the error Copyright O 1994 by the SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 Approved September 1,1994 (914) 761-1 100 SMPTE RP*365 94 W 8357403 0003733 631 RP 165-19
13、94 detection data packet is located just prior to SAV (start of video) in the same lines. To enable proper operation of equipment implementing this practice, signal switching must take place in the vertical interval and conform to SMPTE RP 168. 3.2 Samples included in checkword calculations Starting
14、 and ending samples for active picture and full-field checkword calculations are shown in table 3. For the active picture checkword, only the samples in the active picture area of each line are included in the calculation. As used in this practice, the active picture includes only those lines which,
15、 in composite sys- tems, are full lines (that is, half-lines are not included). Full-field checkwords include all the samples in all lines except the line containing the error detection data packet and the two following lines. The line following the error detection data packet is normally used for v
16、ertical interval switching and the next line is excluded to ensure that word framing and TRS propagation are restored after a switch. I - - - - l i , ccc 1 fff Vertical Blanking Interval (Line n with last full-field sample) (Line n+l with error detection data packet) (Line n+2 used for switching) (L
17、ine n+3 not included in full-field sample) (Line n+4 first full-field samDle1 eef aaa (Line with first active picture sample) Active Picture Area (see 3.2 for definition) H-interval samples not contained in active picture checkword (Line with last active picture sample) eea 1 NOTES 1 See tables 1 an
18、d 2 for exact sample locations in both fields. 2 ccc = location of checkwords and status flags. 3 fff = first sample included in the full-field checkword. 4 aaa = first sample included in the active picture checkword. 5 eea = last sample included in the active picture checkword. 6 eef = last sample
19、included in the full-field checkword. Figure 1 - Location of checkwords and included samples Page 2 of 6 pages RP 165-1994 Table 1 - Location of 52W59.94 system checkwords . . Error checking data locations: Line 9, fields I and III; line 272, fields II and IV 13.5-MHz 18-MHz Data item . . - Ancillar
20、y data header, word 1 - component Ancillary data header, word 2 - component Ancillary data header, word 3 - component Ancillary data flag - composite Data ID Block number Data count Active picture data word O Active picture data word 1 Active picture data word 2 Full-field data word O Full-field dat
21、a word 1 Full-field data word 2 Ancillary data error flags Active picture error flags Full-field error flags Reserved words (7 total) Checksum for this ancillary data block Composite 795 (3Fch) 796 (1 F4h) 797 (200h) 798 (1 1 oh) 799 800 80 1 802 803 804 805 806 807 808-81 4 (200h) 1692 (1 F4h) 1693
22、 (200h) 1694 (1 1 oh) 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704-1 710 (200h) - _or checking data locations: Line 5!fie!ds Data item Ancillary data header, word 1 -component Ancillary data header, word 2 - component Ancillary data header, word 3 - component Ancillary data flag - composite Dat
23、a ID Block number Data count component 2262 (3FFh) 2263 (3FFh) 2261 (oooh) 81 5 171 1 2283 Table 2 - Location of 625/50 system checkwords Active picture data word O Active picture data word 1 Active picture data word 2 Full-field data word O Full-field data word 1 Full-field data word 2 Ancillary da
24、ta error flags Active picture error flags Full-field error flags Reserved words (7 total) Checksum for this ancillary data block 2264 (1 F4h) 2265 (200h) 2266 (1 1 oh) 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276-2282 (200h) and - . III and V - and VII; line 318, fields II and IV and VI and VII
25、I Composite component component 13.5-MHz 18-MHz Y 1138 (oooh) 976 Y 853 978 Y 854 980 Y 855 982 Y 856 984 Y 857 977 cb 427 979 Cr 427 981 cb 428 983 Cr 428 985-991 (200h) cb 429-Cr 4 (200hl O I , Y 861 992 . NOTES 1 Values in the tables are word numbers for the appropriate standard. 2 Values in pare
26、ntheses are sample values. Cr 569 (3FFh) Y 1139 (3FFh) Y 1141 Cb 571 Y 1142 Cr 571 Y 1143 Cb 572 Y 1144 Y 1145 cb 573-Cr Y 1149 Cr 572 (200h) 74 Page 3 of 6 pages SMPTE RP*:Lb5 94 8357403 00017L3 494 W RP 165-1994 NOTE - For the purpose of performing the CRC calculations in PAL composite systems, sa
27、mple 967 is defined as the TRS sample with value 3FFh. This is consistent with IEC 11 79, but must be clearly defined for CRC calculations in case a nonstandard horizontal interval is encountered. through reserved words. The sum should be preset to all zeros at the start of each calculation and igno
28、re the carry. 4.3 Error flags 4 Definition of data words 4.3.1 Definition of individual error status flags 4.1 Checkword values Each checkword consists Of l6 bits Of data tion method. The equation and a conceptual logic diagram are shown below: All error flags indicate only the status of the previou
29、s field; that is, each flag is set or cleared on a field-by- field basis. A logical 1 is the set state and a logical O cahlated using the CRC-CCITT polynomial genera- is the unset state. The flags are defined as follows: edh - error detected here: Signifies that a serial Checkword (16-bit) = X16 + X
30、1* + X5 + 1 101 9 181 71 6 15 14 serial data All data words with values between 3FCh and 3FEh inclusive shall be recoded to 3FFh at the input to the CRC-CCITT polynomial generator. This recoding is necessary only at the polynomial generator, for the purposes of ensuring compatibility between 8-bit a
31、nd 1 O-bit equipment, and between different implementations of serial digital interface TRS and ancillary data flag coding. 4.2 Ancillary data housekeeping, checkwords, and flags Definitions of each ancillary data word specified by this practice are shown in table 4. Zeros are used in the two least
32、significant bits of all words in the data packet to provide compatibility with 8-bit equipment. Bit b7 (V) in picture/field data word 3 is a 1 if a valid CRC has been calculated. This allows implementa- tions which calculate only one or the other of the checkwords. A P in b8 provides even parity for
33、 b7 through bo; that is, the total number of 1 s in b8 through bO is an even number. The most significant bit, b9, is the logical inverse of b8. A checksum is the last word in the error detection data packet as required by the ancillary data formatting for the serial digital interface. The checksum
34、word is used to determine the validity of the included words. The checksum word shall con- sist of 9 bits and is the sum of the 9 least significant bits (b8 through bo) of all words including data ID transmission data error was detected. In the case of ancillary data, this means that one or more ANC
35、 data blocks did not match its check- sum. eda - error detected already: Signifies that a serial transmission data error has been detected somewhere upstream. If device B receives a sig- nal from device A and device A has set the edh flag, when device B retransmits the data to device C, the eda flag
36、 will be set and the edh flag will be unset if there is no further error in the data. idh - internal error detected here: S i g n i f i e s that a hardware error unrelated to serial trans- mission has been detected within a device. This is provided specifically for devices which have internal data e
37、rror checking facilities, as an error reporting mechanism. ida - internal error detected already: S i g n if i es that an idh flag was received and there was a hardware device failure somewhere upstream. ues - unknownerrorstatus: Signifies that a serial signal was received from equipment not support
38、ing this error-detection practice. 4.3.2 Degrees of implementation Individual error status flags, or all error status flags, may not be supported by all equipment. To maintain compatibility with full implementations of this practice, in all such cases where one or more error status flags are not sup
39、ported, the unsupported flag or flags shall be reset (set to O). Page 4 of 6 pages SUPTE RP*Lb5 94 8357401 0001714 320 RP 1611994 525159.94 systems First full-field sample, lines 12 and 275 First active picture sample, lines 21 and 284 795 O 767 767 Last active picture sample, lines 262 and 525 Last
40、 full-field sample, lines 8 and 271 625150 systems First full-field sample, lines 8 and 321 First active picture sample, lines 24 and 336 Last active picture sample, lines 31 O and 622 Last full-field sample, lines 4 and 31 7 1444 1924 O O 1439 1919 1439 1919 972 cb 361 cb 481 O cb 0 cb 0 947 Y 719
41、Y 959 947 Y 719 Y 959 Table 4 - Definition of ancillary data words b9 b8 Data item msb . Ancillary data header, word 1 - component Ancillary data header, word 2 - component Ancillary data header, word 3 - component 1 1 O0 11 Ancillary data flag - composite Data ID 1 1 o1 Block number 10 Data count o
42、1 Active picture data word O crc PP Active picture data word 1 crcil 1 :6 PP Active picture data word 2 creel 5:12 PP - - - Full-field data word O crc Full-field data word 1 crc Full-field data word 2 crc - PP PP PP - - Ancillary data error flags PP Active picture error flags Full-field error flags
43、Reserved words (7 total) Checksum b7 b6 b5 b4 b3 b2 b1 bo Isb O 1 1 1 1 O O c5 c11 v c5 c11 v O O O O s7 O 1 1 1 1 O O c4 c10 O c4 c1 o O ues ues ues O S6 O0 11 11 11 1 1 O0 o1 c3 CP C9 c8 c15 c14 c3 CP c9 c8 c15 c14 ida idh ida idh ida idh O0 s5 s4 - - . O 1 1 1 O O O c1 c7 c13 c1 c7 CI3 eda eda ed
44、a O 53 o o o 1 11 1 11 1 o 01 100 O00 O00 CO o o c6 0 0 c12 o o o O1 O c6 0 CI2 o o edh O edh O O I O edh O o o 0 s2 s1 so NOTE - P and V are defined in 4.2. Page 5 of 6 pages SMPTE RP*lbS 74 8357403 OOOLL5 267 RP 165-t9W Annex A (informative) Bibliography ANSI/SMPTE 125M-1992, Television - Componen
45、t Video Signal 4:2:2 Bit-Parallel Digital Interface EBU Tech 3267-E, Parallel Interface for 625-Line Digital Video Signals ANSI/SMPTE 244M-1993, Television - system M/NTSC Composite Video Signals - Bit-Parallel Digital Interface IEC 1179 (1993), Helical-Scan Digital Composite Video Cassette Recordin
46、g System Using 19 mm Magnetic Tape, Format D-2 (NTSC, PAL, PAL-M), Section Five, Video Inter- face ITU-R T.601, Encoding Parameters of Digital Television ANSI/SMPTE 259M-1993, Television - 10-Bit 4:2:2 Com- ponent and 4fsc NTSC ComPoSite Digital Signals - Serial Digital Interface for Studios SMPTE 267M, Television Bit-Parallel Digital Interface Component Video Signal 4:2:2 16x9 Aspect Ratio ITU-R BT.656, Interfaces for Digital Component Video Signals in 525-Line and 625-Line Television Systems Page 6 of 6 pages
