1、 Rec. ITU-R BT.1685 1 RECOMMENDATION ITU-R BT.1685 Structure of inter-station control data conveyed by ancillary data packets (Questions ITU-R 20/6 and 42/6) (2004) The ITU Radiocommunication Assembly, considering a) that in broadcast station networks, various controls between broadcast stations hav
2、e been performed using control signals multiplexed in the vertical blanking interval of analogue television signals; b) that many countries are installing digital television production, distribution and broadcasting facilities; c) that inter-station control data is also required for the distribution
3、 of digital television signals; d) that Recommendation ITU-R BT.1364 specifies the format of ancillary data signals carried in digital component studio interfaces conforming to Recommendations ITU-R BT.656 and ITU-R BT.1120; e) that some countries are already using the inter-station control data mul
4、tiplexed as ancillary data signals, recommends 1 that, for the transmission of inter-station control data as ancillary data signals conforming to Recommendation ITU-R BT.1364, the specification in Annex 1 should be used. Annex 1 1 General items 1.1 Purpose The purpose of this Annex is to define the
5、structure of inter-station control data which is conveyed using ancillary data packets within component bit-serial interface for standard-definition television systems and bit-serial interfaces for high-definition television systems, and the like, as used inside and outside studios at broadcast stat
6、ions. 1.2 Scope This Annex is applicable to devices which convey inter-station control data for digital broadcasting using ancillary data packets conforming to Recommendation ITU-R BT.1364. 2 Rec. ITU-R BT.1685 1.3 Normative references Some or all of the items defined in the following documents are
7、referenced in this Annex. Recommendation ITU-R BT.1364 Format of ancillary data signals carried in digital component studio interfaces. Recommendation ITU-R BT.1614 Video payload identification for digital television interfaces. 1.4 Terminology 1.4.1 Definition of terminology The terms used in this
8、Annex are defined as follows: Current video or audio mode: The current video or audio mode. Status bit: A continuous signal, which is sent at appropriate intervals and indicates a condition. Down-mix specification Conversion coefficient for signal processing when creating (or DM specification): 2-ch
9、annel stereo from multi-channel stereo with three front channels and two rear channels. Trigger bit: Intermittent signal or pulse used to provide control timing. Next video or audio mode: Video or audio mode, which is intended to be used next. Net cue signal, broadcast- Signal used for inter-station
10、 control and data transmission, transmission-control signal: which is inserted at the vertical blanking interval of television signals. Frame synchronizer (FS): i.e. equipment used for synchronizing non-synchronous television signals. Frame skip: The loss of one frames worth of data. Frame repeat: T
11、he duplication of one frames worth of data. Ancillary data: Various types of signal which are conveyed using the blanking interval for video signals within digital interfaces. 1.4.2 Abbreviations The following abbreviations are used within this Annex. BCD: binary coded decimal BER: bit-error rate EC
12、C: error-correcting code FS: frame synchronizer RS: Reed Solomon Rec. ITU-R BT.1685 3 2 Inter-station control data packet 2.1 Inter-station control data packet format Inter-station control data is conveyed using inter-station control data packets. The format of the inter-station control data packets
13、 shall conform to type 2 ancillary data packets as defined in Recommendation ITU-R BT.1364 and, in this format, one word consists of 10 bits. The format of inter-station control data packets is illustrated in Fig. 1. 1685-013 1 255 111FIGURE 1Inter-station control data packet formatADF DID SDID DC U
14、DW CSADF: Ancillary data flagDID: Data identification word. DID of inter-station control data packet shall be set to 143hSDID: Second data identification word. SDID of inter-station control data packet shall be set to 101hDC: Data count wordUDW: User data wordCS: Check sum wordNote 1: Numbers indica
15、te the number of words. The same applies to Fig. 2 and Fig. 4.Note 2: DID: 25Fhand SDID: 1FEhin the range of “user application” are used in some countries.Note 3: The inter-station control data packet should preferably be placed in the vertical ancillary data space (VANC).2.2 User data word (UDW) fo
16、rmat Inter-station control data uses the UDW of the inter-station control data packet. The UDW comprises an inter-station control data word, an added inter-station control data header word and an error correction parity word (optional). The format of the UDW of an inter-station control data packet i
17、s illustrated in Fig. 2. 1685-0224816FIGURE 2UDW formatUDW (255 words)Inter-station controldata wordInter-station controldata header wordError correction parityword (ECC)2.2.1 Inter-station control data header word An inter-station control data header of a single word is placed at the front of the U
18、DW. Bit assignment for the inter-station control data header word is illustrated in Table 1. 4 Rec. ITU-R BT.1685 TABLE 1 Bit assignment for the inter-station control data header word 2.2.1.1 Error correction identifier The error correction identifier indicates whether or not an error correction par
19、ity word is present. If set to 0 (no error correction), the last six words of the UDW shall not be used and shall be set to 200h. If set to 1 (error correction), the last six words of the UDW constitute an error correction parity word. Code assignment for the error correction identifier is illustrat
20、ed in Table 2. TABLE 2 Error correction identifier 2.2.1.2 CI The CI indicates the state of data packet continuity in the video field unit for interlaced scan systems, or in the video frame unit for progressive scan systems. The CI shall be increased by 1 for each packet by modulo 16. 2.2.2 Inter-st
21、ation control data word The lower 8 bits (b0 through b7) of the inter-station control data word constitute the inter-station control data. Bit assignment for the inter-station control data word is illustrated in Table 3. Bit number Description b9 (MSB) Not b8 b8 Even parity for b0 through b7 b7 Erro
22、r correction identifier b6 b5 b4 Undefined(1)b3 b2 b1 b0 (LSB) Continuity index (CI) (1)Undefined bits shall be set to 0 (zero) until defined. LSB: least significant bit. MSB: most significant bit. b7 Description 0 No error correction 1 Error correction Rec. ITU-R BT.1685 5 TABLE 3 Bit assignment fo
23、r the inter-station control data word 2.2.2.1 Inter-station control data format The format of inter-station control data is illustrated in Fig. 3. 1685-03b7b6b5b4b3b2b1b0111128 29 30 311132 3341122-25 26 278941-8 9-17 18-211 1 1 1 1 1 1 1 1 1 64 14134 35 36 37 38 39 40 41 42 43 44-107 108-248FIGURE
24、3Inter-station control data formatTrigger bitsVideo mode Audio modeTrigger countdown Status bitsTrigger counterQ1counterQ2counterQ4counterQ1countdownQ2countdownQ3counterQ3countdownQ4countdownReservedareaPrivate areaTransmitting-stationcodeTransmitting-stationtimeCurrentvideo modeNextvideomodeVideo m
25、odecountdownAudiomodecountdownCurrent audiomodeNextaudiomodeCurrentDMspecificationNextDMspecificationQ8 Q16 Q24 Q32Q7 Q15 Q23 Q31Q6 Q14 Q22 Q30Q5 Q13 Q21 Q29Q4 Q12 Q20 Q28Q3 Q11 Q19 Q27Q2 Q10 Q18 Q26Q1 Q9 Q17 Q25BitnumberWordsWordnumberS8 S16S7 S15S6 S14S5 S13S4 S12S3 S11S2 S10S1 S9DM specification:
26、 Down-mix specification. Bit number Description b9 (MSB) Not b8 b8 Even parity for b0 through b7 b7 b6 b5 b4 b3 b2 b1 b0 (LSB) Inter-station control data 6 Rec. ITU-R BT.1685 The following describes the format and implementation of each item of inter-station control data: a) Transmitting-station cod
27、e (8 words) The transmitting-station code is used to provide display equipment with the name of the transmitting station. If no transmitting-station code is sent, all characters shall be spaces. b) Transmitting-station time (9 words) The transmitting-station time is used to provide information regar
28、ding the time at the transmitting station. Specifically, 4-bit BCD is used to encode the year, month, date, day, hour, minute, second, and millisecond. This encoding method is illustrated in Table 4. TABLE 4 Coding of transmitting-station time The lower 8 bits of unsent words shall be set to FFh. Th
29、e following values are valid: Year: Decimal values from 0 to 99 (Further studies to convert this value to the four decimal format might be needed.) Month: Decimal values from 1 to 12 Date: Decimal values from 1 to 31 Day: Decimal values from 0 to 6 Hour: Decimal values from 0 to 23 Minute and second
30、: Decimal values from 0 to 59 Millisecond: Decimal values from 0 to 999. Date section Time section ms section Year Month Date Day Hour(1)min s ms Word position W0 W1 W2 W3 W4 W5 W6 W7 W8 b7 (MSB) b6 Order of 10 0 0 Order of 10 b5 (BCD) (BCD) b4 Order of 10 (BCD) b3 b2 Order of 1 (2)Order of 1 Order
31、of 100 Order of 1 b1 (BCD) (BCD) (BCD) (BCD) Bit number b0 (LSB) (1)The 24-hour system is used. (2)Sunday (0h), Monday (1h), Tuesday (2h), Wednesday (3h), Thursday (4h), Friday (5h), and Saturday (6h). Rec. ITU-R BT.1685 7 c) Current video mode, next video mode (4 words) Current video mode and next
32、video mode are used to indicate video attributes. Specifically, current video mode corresponds to the current attribute; next video mode to the next scheduled attribute. Both current video mode and next video mode are encoded as illustrated in Table 5. By setting the lower 8 bits from the first word
33、 (W0) to 00h, it can be indicated that all four words from the corresponding current video mode or next video mode are unused. TABLE 5 Encoding of video mode TABLE 6 Encoding of video format and digital interface Word position W0 W1 W2 W3 b7 Version identification: Normally 1 Scan format for transmi
34、ssion: Interlace (0) or progressive (1) NOTE 1: Valid when W0 = 85hVideo aspect ratio: 4:3 (0) or 16:9 (1) Reserved area b6 Scan format for picture: Interlace (0) or progressive (1) No. of horizontal Y samples: 720 (0) or 960 (1) NOTE 1: Valid when W0 = 81hChannel allocation: No. 1 link (0) or No. 2
35、 link (1) NOTE 1: Valid when W0 = 82hb5 Display range aspect ratio: 4:3 (0) or 16:9 (1) b4 Reserved area Reserved area b3 b2 b1 Reserved area Bit number b0 Video format and digital interface (Table 6) Frame rate (Table 7) Sampling structure (Table 8) Bit depth: 8 bits (0) or 10 bits (1) NOTE 1 The i
36、tems valid only for specific W0-values are treated as reserved areas when other W0-values are specified. Code value Video format Digital interface 01h525i, 625i 270 Mbit/s, 360 Mbit/s 02h525p, 625p 360 Mbit/s single link, 270 Mbit/s dual link 03h525i/p, 625i/p 540 Mbit/s 04h750p 1.485 Gbit/s (nomina
37、l) 05h1125i/p 1.485 Gbit/s (nominal) 06hto 7FhReserved 8 Rec. ITU-R BT.1685 TABLE 7 Encoding of frame rate TABLE 8 Encoding of sampling structure d) Current audio mode, next audio mode (1 word ) Current audio mode and next audio mode indicate the attributes of the audio conveyed together with the vi
38、deo signal. Specifically, current audio mode corresponds to the current attribute; next audio mode to the next scheduled attribute. The lower 5 bits (b0 through b4) of current audio mode and Code value Frame rate (Hz) 0hUndefined 1hReserved 2h24/1.001 3h24 4hReserved 5h25 6h30/1.001 7h30 8hReserved
39、9h50 Ah60/1.001 Bh60 Chto FhReserved Code value Sampling structure 0h4:2:2 (Y/CB/CR) 1h4:4:4 (Y/CB/CR) 2h4:4:4 (G/B/R) 3h4:2:0 4h4:2:2:4 (Y/CB/CR/A) 5h4:4:4:4 (Y/CB/CR/A) 6h4:4:4:4 (G/B/R/A) 7hReserved 8h4:2:2:4 (Y/CB/CR/D) 9h4:4:4:4 (Y/CB/CR/D) Ah4:4:4:4 (G/B/R/D) Bhto FhReserved NOTE 1 With regard
40、 to 4:2:2:4 and 4:4:4:4, A refers to the video channel, and D refers to the non-video (i.e. data) channel. Rec. ITU-R BT.1685 9 next audio mode provide audio mode data; the upper 3 bits (b5 through b7) provide information regarding the down-mix specification. Encoding of each word is illustrated in
41、Table 9a and Table 9b. However, a down-mix specification is valid only when the audio mode contains a 3/2 or 5.1 format, and in all other cases, this shall be encoded as 000. TABLE 9a Encoding of audio mode (b0 to b4) Code value Audio mode 00hUnused 01hM 02h2M(D) 03h3M(D + M) 04h4M(2D) 05h5M(2D + M)
42、 06h6M(3D) 07h7M(3D + M) 08h8M(4D) 09hS 0Ah2S 0Bh3S 0Ch4S 0Dh3/0 0Eh2/1 0Fh3/1 10h2/2 11h3/2 12h3/2/Low frequency effects (LFE) (5.1) 13hS + M 14hS + D 15h5.1 + S 16h3/1 + S 17h3/2 + S 18h9M or more (M only) 19h5S or more (S only) 1AhOther 1Bhto 1FhReserved M: mono S: stereo D: dual mono (2-channel
43、audio). Number of channels for front/rear speakers. Example: 3/2 = 3 front, 2 rear. 10 Rec. ITU-R BT.1685 TABLE 9b Encoding of down-mix specification (b5 to b7) e) Video mode countdown, audio mode countdown (1 word) Countdowns are used to provide timing information for video mode and audio mode. Spe
44、cifically, they count down the time remaining until mode-switch timing in video field units; however, there is no concept for video field units when attached to progressive-scan video signals, and consequently, countdown is carried out in video frame units. Encoding is not carried out using BCD; rat
45、her, values between 0 and 254 are expressed in 8-bit format. A value of FFhindicates that countdown is not being carried out. Code value b7 b6 b5 Matrix-mixdown coefficient 0 0 0 Unspecified 0 0 1 0 1 0 0 1 1 Reserved 1 0 0 21=A 1 0 1 2/1=A 1 1 0 )( 221=A 1 1 1 0=A NOTE 1 A two-channel stereo signal
46、 or a mono signal can be generated within a matrix-mixdown decoder by use of the following equations: 2211122111SSRACRARLACLAL+=+= )(231SSRLARCLAM += where: L, C, R, LSand RS: source signals L and R : derived stereo signal M : derived mono signal A : matrix-mixdown coefficient. LFE channels are omit
47、ted from the mixdown. Rec. ITU-R BT.1685 11 f) Trigger bits Q1 through Q32 (1 bit) Trigger bits are used to provide notification of a specific event either in advance or at the required timing. Trigger send is considered to commence when the trigger bit switches from 0 to 1, and the meaning of the b
48、it, send timing, and send duration are arbitrary. g) Trigger counter (1 word ) Trigger counters are used with trigger bit Q1 through Q4. Encoding is not carried out using BCD; rather, values between 0 and 254 are expressed in 8-bit format. A value of FFhindicates that the trigger counter is not bein
49、g used. h) Trigger countdown (1 word ) Trigger countdowns are used to provide timing information for trigger bits Q1 through Q4. Specifically, they count down the time remaining until the timing specified for the trigger bit in field units; however, there is no concept for field units when attached to progressive-scan video signals, and consequently, countdown is carried out in frame units. Encoding is not carried out using BCD; rather, values between 0 and 254 are expressed in 8-bit format. A value of
