1、BRITISH STANDARD BS 7133:1989 IEC 841:1988 Incorporating Amendment No. 1 Specification for Audio recording-PCM encoder/decoder system (Implementation of CENELECHD544S1)BS7133:1989 This British Standard, having been prepared under the directionof the Electronic Equipment Standards Policy Committee, w
2、as published underthe authority of the BoardofBSI and comes intoeffecton 29 September 1989 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference EEL/22 Draft for comment BSI News July1988 ISBN 0 580 174719 Committees responsible for this British Standard T
3、he preparation of this British Standard was entrusted by the Electronic Equipment Standards Policy Committee (EEL/-) to Technical Committee EEL/22, upon which the following bodies were represented: British Broadcasting Corporation British Kinematograph, Sound and Television Society Council for Educa
4、tional Technology for the United Kingdom Electronic Engineering Association Independent Broadcasting Authority Independent Television Association Sound and Communication Industries Federation The following bodies were also represented in the drafting of the standard, through subcommittees and panels
5、: British Educational Equipment Association British Tape Industry Association Royal Television Society Amendments issued since publication Amd. No. Date of issue Comments 6718 August 1991 Indicated by a sideline in the marginBS7133:1989 BSI 12-1999 i Contents Page Committees responsible Inside front
6、 cover National foreword iii 1 Scope 1 2 Object 1 Section 1. General 3 System description 1 Section 2. Format of the recorded signal 4 General 1 5 Transmission rate 1 6 Configuration of the synchronizing signal 1 6.1 Horizontal synchronizing signal 1 6.2 Vertical synchronizing signal 1 7 Configurati
7、on of the horizontal line 1 7.1 Data synchronizing signal 1 7.2 Data block 1 7.3 White reference signal 2 7.4 Assignment in the horizontal period 2 8 Configuration of the vertical field 2 8.1 Audio data block line 2 8.2 Control data block line 2 8.3 Assignment in the vertical field 2 Section 3. Sour
8、ce encoding 9 Audio signal 2 9.1 Number of audio channels 2 9.2 Emphasis 2 10 Source encoding 2 10.1 Sampling 2 10.2 Quantization 2 10.3 Coding 3 Section 4. Data block 11 Configuration of the audio data block 3 11.1 General 3 11.2 Sampled signal word 3 11.3 Error correcting word 3 11.4 Interleaving
9、4 11.5 Error detecting word 4 11.6 Assignment in the audio data block 4 12 Configuration of the control data block 4 12.1 General 4 12.2 Cueing word 4 12.3 Content identification word 5 12.4 Address word 5 12.5 Control word 5 12.6 Error detecting word 5 12.7 Assignment in the control data block 5 Ap
10、pendix A Noise level in back porch 11 Appendix B Error correcting word 11 Appendix C Videocassette system considerations 11BS7133:1989 ii BSI 12-1999 Page Figure 1a Horizontal period (60 fields/525 lines) 6 Figure 1b Horizontal period (50 fields/625 lines) 6 Figure 2a Vertical synchronizing signal (
11、60 fields/525 lines) 6 Figure 2b Vertical synchronizing signal (50 fields/625 lines) 7 Figure 3a Assignment in horizontal period (60 fields/525 lines) 7 Figure 3b Assignment in horizontal period (50 fields/625 lines) 8 Figure 4a Assignment in vertical fields (60 fields/525 lines) 8 Figure 4b Assignm
12、ent in vertical field (50 fields/625 lines) 9 Figure 5 Pre-emphasis and de-emphasis 9 Figure 6 Sampled signal word 10 Figure 7 Assignment in audio data block 10 Figure 8 Assignment in address word 10 Figure 9 Assignment in control data block 10 Figure B.1 Assignment in the audio data block 11 Table
13、I Status of control word 10 Publications referred to Inside back coverBS7133:1989 BSI 12-1999 iii National foreword This British Standard has been prepared under the direction of the Electronic Equipment Standards Policy Committee and is identical with IEC 841:1988 “Audio recording PCM encoder/decod
14、er system”, published by the International Electrotechnical Commission (IEC). This British Standard is also in agreement with Harmonization Document HD 544 S1, published by the European Committee for Electrotechnical Standardization (CENELEC). A British Standard does not purport to include all the n
15、ecessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard IEC 767:1983 BS 6502:1984
16、Specification for helical-scan video tape cassette system using 12.65 mm (0.5 in) magnetic tape on type Beta format (Identical) IEC 774:1983 BS 6482:1984 Specification for helical-scan video tape cassette system using 12.65 mm (0.5 in) magnetic tape on type VHS (Identical) Summary of pages This docu
17、ment comprises a front cover, an inside front cover, pages i to iv, pages1to 12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.iv blankBS7133
18、:1989 BSI 12-1999 1 1 Scope This standard applies to the reversible process achieved by the PCM encoder/decoder system that transforms two audio signals into one PCM signal for compatibility with either the 60 fields/525 lines or the 50 fields/625 lines television system. 2 Object This standard has
19、been prepared to establish the signal format and other conditions required for the PCM encoder/decoder system that is intended for recording and reproducing audio signals in the form of a PCM signal through (part of) a domestic videocassette system. The standard seeks to achieve standardized system
20、operation, compatibility of encoder/decoder systems with players and systems, and interchangeability of recorded tapes. Section 1. General 3 System description The encoder of the PCM encoder/decoder transforms two audio signals into a PCM signal with redundant information added to correct occasional
21、 errors arising during recording or reproduction. The signal thus encoded is converted to a format that conforms to the relevant television system for recording on to a videocassette (see note). The PCM signal is retrieved from the video signal by the videocassette system and most of the occasional
22、errors are corrected by using the redundant information. The decoder of the PCM encoder/decoder transforms the PCM signal into two audio signals. NOTEVideocassette systems for household use are specified in IEC Publications 767 and 774. Section 2. Format of the recorded signal 4 General The format o
23、f the recorded signal shall be compatible with the signal of the relevant televisionsystem, either 60 fields/525 lines or50fields/625 lines. 5 Transmission rate The transmission rate shall be as follows: 2.646 Mbit/s for the 60 fields/525 lines system; 2.625 Mbit/s for the 50 fields/625 lines system
24、. 6 Configuration of the synchronizing signal 6.1 Horizontal synchronizing signal The horizontal period containing the horizontal synchronizing signal shall be composed as shown in Figure 1a and Figure 1b. 6.2 Vertical synchronizing signal The vertical synchronizing signal with equalizing pulses sha
25、ll be composed as shown in Figure 2a and Figure 2b. 7 Configuration of the horizontal line 7.1 Data synchronizing signal The data synchronizing signal shall consist of 4 bits as follows: “1 0 1 0” 7.2 Data block The data block shall consist of 128 bits and shall be NRZ (Non Return to Zero) modulated
26、.BS7133:1989 2 BSI 12-1999 7.3 White reference signal The white reference signal shall have a width of4bits and peak white level. 7.4 Assignment in the horizontal period One horizontal period shall consist of 168 bits. The data synchronizing signal, the data block and the white reference signal shal
27、l be assigned into the horizontal period as shown in Figure 3a and Figure 3b. Each voltage level shall be measured when terminated by a 75 7 load. The tolerance of each level shall be 10% (seeAppendix A). 8 Configuration of the vertical field 8.1 Audio data block line The audio data block line shall
28、 occupy the horizontal period containing the audio data block specified in Clause 11. 8.2 Control data block line The control data block line shall occupy the horizontal period containing the control data block specified in Clause 12. 8.3 Assignment in the vertical field Each field shall be headed b
29、y the vertical synchronizing signal with the equalizing pulse. In the case of the 60 fields/525 lines system, as shown in Figure 4a, the control data block line shall be located at the 10th line for an odd field and 10.5th line for an even field. The 245 audio data block lines shall follow the contr
30、ol data block line. In the case of the 50 fields/625 lines system, as shown in Figure 4b, the control data block line shall be located at the 6th line for the first (third) field and 6.5th line for the second (fourth) field. The 294 audio data block lines shall follow the control data block line. Th
31、e remaining lines in the field shall be left blank for both systems. Section 3. Source encoding 9 Audio signal 9.1 Number of audio channels The number of recorded audio channels shall be two, and shall be designated as A and B. Channels A and B correspond to the left and right channels, respectively
32、, for stereophonic use. 9.2 Emphasis Pre-emphasis may be performed on the audio signal. In that case, the time constants t 1and t 2shall be as follows: The characteristics of the pre-emphasis and de-emphasis are shown in Figure 5. 10 Source encoding 10.1 Sampling The sampling rate shall be 44.100 kH
33、z 0.01%. It is recommended that both channels be sampled simultaneously. It is permissible that the two channels be sampled alternately in the sequence of channel A followed by channel B. 10.2 Quantization The sampled signal shall be recorded with 14-bit or16-bit linear encoding. NOTEThe main body o
34、f this standard describes 14-bit encoding. Appendix B describes 16-bit encoding. t 1= 50 4s t 2= 15 4sBS7133:1989 BSI 12-1999 3 10.3 Coding Twos complement binary code shall be used. A positive binary code shall represent a positive audio signal voltage. Section 4. Data block 11 Configuration of the
35、 audio data block 11.1 General The audio data block shall consist of six sampled signal words, two error correcting words and one error detecting word. 11.2 Sampled signal word The sampled signal word shall consist of 14 bits with the MSB (Most Significant Bit) being bit 1 and the LSB (Least Signifi
36、cant Bit) being bit 14 as shown in Figure 6. The nth sampled signal words for channels A and B are designated A nand B nrespectively. 11.3 Error correcting word Each of the error correcting words, designated P nand Q n , shall consist of 14 bits generated by the following equations (see Appendix B):
37、 P n= A n+ B n+ A n+1+ B n+1+ A n+2+ B n+2 Q n= T 6 A n+ T 5 B n+ T 4 A n+1+ T 3 B n+1+ T 2 A n+2+ TB n+2 Calculations shall be performed modulo 2. The generating matrix T shall be defined as follows: where: n is 0 or a multiple of 3 T is a generating matrixBS7133:1989 4 BSI 12-1999 The sampled sign
38、al words, A nand B nare expressed in the following column matrix: 11.4 Interleaving The eight word sequence consisting of six sampled signal words and two error correcting words is as follows: A n , B n , A n+1 , B n+1 , A n+2 , B n+2 , P n , Q n Interleaving of distance D shall be performed on the
39、above sequence. As a result of the interleaving, the interleaved eight word sequence is shown as follows: A n , B n3D , A n+16D , B n+19D , A n+212D , B n+215D , P n18D , Q n21D The distance D shall be equal to 16, which corresponds to 48 words. 11.5 Error detecting word The error detecting word, de
40、signated CRC, consists of 16 bits generated by the following method. “1”s shall be added, modulo 2, to each of the first16bits of the interleaved eight word sequence (112 bits). After addition, each bit of the sequence corresponds to the coefficients of a polynominal having terms fromX 127down to X
41、16 . This polynominal is divided, modulo 2, by the following generating polynominal: G(X) = X 16+ X 12+ X 5+ 1 The error detecting word is given by the coefficients of the terms from X 15to X 0in the remainder polynominal resulting from the completion of this division. NOTEThe CRC is expressed as fo
42、llows: 11.6 Assignment in the audio data block Each word shall be assigned in the order: sampled signal words, error correcting words and error detecting word in one data block as shown in Figure 7. 12 Configuration of the control data block 12.1 General The control data block shall consist of a cue
43、ing word, a content identification word, an address word, a control word and an error detecting word. 12.2 Cueing word The cueing word shall consist of 56 bits as follows: “110011001100 . . . 1100” CRC = (1 + b 1 ) X 127+ (1 + b 2 ) X 126+ . . . + (1 + b 16 ) X 112 + b 17X 111+ b 18X 110+ . . . + b
44、112X 16mod G(X) where: b 1is the most significant bit of A nand b 112is the least significant bit of Q n21D .BS7133:1989 BSI 12-1999 5 12.3 Content identification word The content identification word shall consist of14bits. In this standard it shall be all 0s. 12.4 Address word The address word shal
45、l consist of 28 bits and shall be divided into three separate codes: an index code, a time code and a field code. Each code shall be expressed as a binary number. 12.4.1 Index code The index code shall consist of 6 bits within the range of “000000 (00)” through “111111 (3F)”. The updating of the ind
46、ex code shall be controlled at recording time. 12.4.2 Time code The time code shall consist of 16 bits and shall be divided into “hour”, “minute” and “second”. The “hour” shall consist of 4 bits. The “minute” shall consist of 6 bits and shall be carried to the “hour” at every 60th count. The “second
47、” shall consist of 6 bits and shall be carried to the “minute” at every 60th count. The values of the “hour”, the “minute” and the “second” shall be reset by the control at recording time to zero or to preset values. 12.4.3 Field code The field code shall consist of 6 bits and shall be carried at ev
48、ery 60th count for the 60 fields/525 lines system and at every 50th count for the 50 fields/625 lines system, respectively. The value of the field code shall be counted at every field specified in Clause8. Odd and even numbers shall be assigned to odd and even fields, respectively. The field code sh
49、all be reset by the control at recording time. 12.4.4 Code assignment in the address word The index code, the time code and the field code shall be assigned within the address word, as shown in Figure 8. Each code shall be laid out so that the MSB comes first and the LSB comes last. 12.5 Control word The control word shall consist of 14 bits as shown in Table I. 12.6 Error detecting word The error detecting word, designated CRC, shall consist of 16 bits and shall be generated from the 112-bit sequence of the cueing wo
