1、 Rec. ITU-R BT.1577 1 RECOMMENDATION ITU-R BT.1577 Serial digital interface-based transport interface for compressed television signals in networked television production based on Recommendation ITU-R BT.1120 (Question ITU-R 5/6) (2002) The ITU Radiocommunication Assembly, considering a) that the hi
2、gh definition serial digital interface (HD-SDI) is being implemented in television production studios and that it is documented in Recommendation ITU-R BT.1120; b) that Recommendation ITU-R BR.1356 User requirements for application of compression in television production, already exists; c) that mai
3、ntaining video signals in compressed form as far as possible throughout the production and post-production process offers the potential of increased operating efficiency; d) that programme data composed of audio, compressed video and metadata should be streamed in a container commonly available in t
4、he high-definition production studio; e) that a transport mechanism must be established which allows point-to-point and point-to-multipoint routing of these data through a digital production and post-production chain; f) that the transport should allow synchronous data transfer to facilitate absolut
5、e and relative timing between programme data; g) that the transport mechanism should allow faster than real-time and non-real time transfer of programme data, recommends 1 that for applications based on the HD-SDI infrastructure in networked production and post-production based on Recommendation ITU
6、-R BT.1120 the high definition serial data transport interface (HD-SDTI) described in Annex 1 should be used. 2 Rec. ITU-R BT.1577 ANNEX 1 SDI-based transport interface for compressed television signals in networked television production 1 Introduction This Recommendation specifies a data stream use
7、d to transport packetized data within a studio/production centre environment. The data packets and synchronizing signals are compatible with Recommendation ITU-R BT.1120 (see Fig. 1). This Recommendation describes the assembly of two channels of 10-bit words multiplexed onto one HD-SDI line for the
8、purpose of transporting the data streams in a structured framework. The HD-SDTI data blocks and synchronizing signals provide a data transport protocol that can readily be added to the infrastructure described in Recommendation ITU-R BT.1120. Recommendation ITU-R BT.1120 requires a sequence of 10-bi
9、t words which define a television horizontal line comprising five areas in the following sequence (Note The first two areas are often described together): EAV: a 4-word unique timing sequence defining the end of active video (EAV) (of the previous line); LN/CRC: 2 words defining the line number (LN)
10、 followed by a 2-word cyclic redundancy check (CRC) error detection code; digital line blanking; SAV: a 4-word unique timing sequence defining the start of active video (SAV); and digital active line. An associated television source format standard defines the rate of television horizontal lines by
11、defining the following parameters: the number of words per line; the number of words in the digital active line (and hence the number of words in the digital line blanking period); the number of lines per frame; the number of frames per second. Recommendation ITU-R BT.1120 currently defines several
12、source formats. Recommendation ITU-R BT.656 defines the meaning of the EAV and SAV word sequences which can be applied to all relevant source formats. A decoder compliant with this Recommendation shall not be required to decode all the source formats available to Recommendation ITU-R BT.1120. The so
13、urce formats that must be supported by the decoder shall be specified in application recommendations. Rec. ITU-R BT.1577 3 1.1 HD-SDTI mapping onto HD-SDI The source formats, in combination with Recommendation ITU-R BT.1120, describe the bit-serial format formed from C/Y word-multiplexed channels as
14、 illustrated in Fig. 1. 1577-01C data inputClock inputY data input10 bits10 bitsC data outputClock outputY data output10 bits10 bitsSerial data Serial dataEqualizerHD-SDIencoderHD-SDIdecoderC data inputClock inputY data input8 (9) bits8 (9) bitsC data outputClock outputY data output8 (9) bits8 (9) b
15、itsBT.1120HD-SDTIformatterHD-SDTIdeformatterC dataClockY data10 bits10 bitsC dataClockY data10 bits10 bitsHD-SDTIBT.1120FIGURE 1Arrangement of HD-SDTI wrapped around Recommendation ITU-R BT.1120The HD-SDTI data shall be serialized, scrambled, coded, and interfaced according to Recommendation ITU-R B
16、T.1120 and the associated source format standard. The signal specifications and connector types shall be as described in Recommendation ITU-R BT.1120. The data word length shall be 10 bits defined as bits B0 through to B9. B0 is the least significant bit (LSB) and B9 is the most significant bit (MSB
17、). The order of bit-transmission shall be LSB first as defined in Recommendation ITU-R BT.1120. Source data shall be in groups of four 10-bit words representing a word-multiplexed CB, Y1, CR, Y2signal, where CBand CRform one parallel C-data channel and Y1and Y2form a second parallel Y-data channel.
18、The C/Y word clock rate shall be exactly 74.25 MWords/s for those picture rates which are an exact integer number per second and shall be 74.25/1.001 MWords/s for those picture rates which are offset by a divisor of 1.001. The bit clock rate shall be 20 times the C/Y word clock rate (i.e. 1.485 Gbit
19、/s or 1.485/ 1.001 Gbit/s). 4 Rec. ITU-R BT.1577 The timing reference signals, EAV and SAV, shall occur on every line and shall be C/Y interleaved as described in the source format document. The LN and CRC shall occur on every line and shall be C/Y interleaved as described in Recommendation ITU-R BT
20、.1120. The HD-SDTI header data shall be encapsulated by an ancillary data packet according to Recommendation ITU-R BT.1364 and placed in the data space between the end of the EAV/LN/CRC and the beginning of the SAV. The HD-SDTI payload shall be placed between the end of the SAV and the beginning of
21、the EAV. There shall be space for two HD-SDTI header data and payloads per line. The first HD-SDTI header data and payload shall use the C data channel and the second HD-SDTI header data and payload shall use the Y data channel. The two channels shall be word multiplexed according to Recommendation
22、ITU-R BT.1120. Each C/Y multiplexed line is treated as a separate HD-SDTI payload. Any line may carry an HD-SDTI payload on either the C-channel or the Y-channel. Where a line carries both C-channel and Y-channel payloads, the C-channel payload shall be assumed first in time, followed by the Y-chann
23、el payload. Figure 2 shows the data placement of the two HD-SDTI header data and payloads for one line. 1577-02H-ancillaryspaceC-channel payload areaFIGURE 2General layout of the dual-channel HD-SDTI header data and payloadEAV/LN/CRCC-channelheaderdataC-channel user data areaSAVC-channel ancillary d
24、ataY-channel payload areaEAV/LN/CRCY-channelheaderdataY-channel user data areaSAVY-channel ancillary dataH-ancillaryspace1.2 Extended mode for constant payload data rate The default HD-SDTI payload for each channel is the defined C/Y active line-channel period for the source format at all picture ra
25、tes. An optional extension mode allows source formats that would otherwise reduce the payload data rate to advance the timing of the SAV marker so that the payload data rate remains a constant value. In extended mode, the constant payload data rate value is either Rec. ITU-R BT.1577 5 exactly 129.6
26、Mbit/s or 129.6/1.001 Mbit/s depending on whether the frame rate of the source format includes a 1.001 divisor. The payload lengths associated with particular source formats are given in Table 1. TABLE 1 Payload length extension values for varying source frame rates 1.3 Double-rate operation The sou
27、rce format may allow frequencies of double the baseline rate to accommodate the carriage of progressively scanned pictures at the rates of 50 Hz, 60/1.001 Hz and 60 Hz for some source formats. The use of double-rate sampling frequencies is allowed within this Standard as a specified extension. The e
28、ffect is a doubling of the number of line-channels per second and there is no effect on the data structure within each line-channel save doubling of the clock rates. This is a significant extension of the source format capability and only specified equipment may support this operation. Users are cau
29、tioned to check whether double clock rate is supported by the HD-SDI infrastructure and the HD-SDTI decoder. 1.3.1 Header data specifications For each line-channel carrying an HD-SDTI payload, HD-SDTI header data shall be encapsulated by an ancillary data packet conforming to a Recommendation ITU-R
30、BT.1364 ancillary data packet structure (type 2) as shown in Table 2. TABLE 2 HD-SDTI ancillary data packet structure Frame rate Lines per frame Samples per line Blanking length Payload length Payload rate 25 1 125 2 640 336 2 304 129.6 Mbit/s 24 (24/1.001) 1 125 2 750 350 2 400 129.6 Mbit/s NOTE 1
31、Not all equipment may support the extended mode. Users are cautioned to check whether advancement of the SAV is supported by the HD-SDI infrastructure and the HD-SDTI decoder. Name Acronym Value Ancillary data flag (10-bit words) ADF 000h, 3FFh, 3FFhData identification DID 40hSecondary data identifi
32、cation SDID 02hData count DC 2AhHD-SDTI header data 42 words Check sum CS 6 Rec. ITU-R BT.1577 The total size of the ancillary data packet shall be 49 words of which the HD-SDTI header data comprises the 42 words as shown in Table 3. The structure of the HD-SDTI header data packet is further describ
33、ed in Fig. 3. TABLE 3 HD-SDTI header data 1577-0312Ah102h140h3FFh3FFh000hDestinationaddressHD-SDTI header dataFIGURE 3Header data structureEAV (3words)LNHD-SDTI header data ancillary data packetCRCDIDSDIDDatacountAAIandcodeADF (3words)SourceaddressReserved(5 words)BlocktypeCRC flagHeaderCRC (2words)
34、Check sumHD-SDTI header data shall be located immediately after the EAV/LN/CRC sequence, as shown in Fig. 3, on lines specified in the application document. In the special case of HD-SDTI applications that embed digital audio according to Recommendation ITU-R BT.1365, the HD-SDTI header data packets
35、 shall be placed immediately following any such Recommendation ITU-R BT.1365 ancillary data packets. For line-channels that do not carry an HD-SDTI payload, the Block Type ( 4.4) shall be set to a value of 00h to indicate a null payload (plus definition of other header data). All data in the HD-SDTI
36、 header data shall use 8-bit words using bits B0 to B7 of each word. For all words of the HD-SDTI header data, bit B8 shall be the even parity of bits B0 to B7 and bit B9 shall be the complement of bit B8. Name Word length Code and authorized address identifier (AAI) 1 word Destination address 16 wo
37、rds Source address 16 words Block type 1 word CRC flag 1 word Reserved data 5 words Header CRC 2 words Rec. ITU-R BT.1577 7 1.4 Ancillary data formatting The ADF, DID, SDID, DC and CS data words shall conform to Recommendation ITU-R BT.1364. All data in the ancillary packet following the ADF shall b
38、e 8-bit words where the word value is defined by bits B7 through B0; Bit B8 is even parity of bits B7 through B0 and bit B9 is the complement of bit B8. 1.4.1 Data ID (DID) The data ID shall have the value 40hfor bits B7 through B0. 1.4.2 Secondary data ID (SDID) The secondary data ID shall have the
39、 value 02hfor bits B7 through B0.1.4.3 Data count (DC) The DC shall represent 42 words for the header and have the value 2Ahfor bits B7 through B0. 1.5 AAI and code Both AAI and code shall consist of 4 bits (see Fig. 4). AAI shall comprise bits B7 to B4. Code shall comprise bits B3 to B0. 1577-04FIG
40、URE 4Assignment of AAI and code bitsB7B6B5B4B3B2B1B0CodeAAI1.5.1 AAI The AAI shall identify the format of both the destination and source address words from one of 16 different states. 8 Rec. ITU-R BT.1577 TABLE 4 Assignment of payload size The value 0h is reserved for applications where no source a
41、nd destination address format is specified. In this case, any non-zero value in the source and destination address shall be ignored. 1.5.2 Code Code shall identify the length of the payload which shall be contained in the area between the SAV and EAV timing reference points. TABLE 5 Assignment of pa
42、yload size The value 0h is reserved to carry a line-channel of SDI signal in the active line-channel area. Code values higher than 8h shall only be used if the HD-SDTI is being used in extended mode with support for advanced SAV positioning as detailed in Table 1. Address identification B7 B6 B5 B4
43、Unspecified format 0 0 0 0 IP-v6 addressing 0 0 0 1 Payload bits B3 B2 B1 B0 SDI 0 0 0 0 1 440 words 0 0 0 1 1 920 words 0 0 1 0 1 280 words 0 0 1 1 Reserved for 143 Mbit/s applications 1 0 0 0 2 304 words (extension mode) 1 0 0 1 2 400 words (extension mode) 1 0 1 0 1 440 words (extension mode) 1 0
44、 1 1 1 728 words (extension mode) 1 1 0 0 2 880 words (extension mode) 1 1 0 1 3 456 words (extension mode) 1 1 1 0 3 600 words (extension mode) 1 1 1 1 Reserved but not defined All other codes Rec. ITU-R BT.1577 9 1.6 Destination and source address The destination and source address represents the
45、address of the devices within the connection according to the AAI. 16 bytes are allocated for both destination and source address with the bit allocation for each address as shown in Fig. 5. 1577-05A120A121A122A123A124A125A126A127A112A113A114A115A116A117A118A119A104A105A106A107A108A109A110A111A96A97
46、A98A99A100A101A102A103A88A89A90A91A92A93A94A95A80A81A82A83A84A85A86A87A72A73A74A75A76A77A78A79A64A65A66A67A68A69A70A71A56A57A58A59A60A61A62A63A48A49A50A51A52A53A54A55A40A41A42A43A44A45A46A47A32A33A34A35A36A37A38A39A24A25A26A27A28A29A30A31A16A17A18A19A20A21A22A23A8A9A10A11A12A13A14A15A0A1A2A3A4A5A6A7
47、FIGURE 5Assignment of payload sizeThe default condition when neither destination nor source address is required is that all 16 bytes of the destination and source addresses shall be set to 00h in accordance with AAI = 0h. When all 16 bytes of the destination address are zero filled in accordance wit
48、h AAI = 0h, it shall indicate a universal address to all destination devices connected to the interface. 1.7 Block type The block type shall consist of one word comprising bits B7 to B0. The block type shall define the segmentation of the payload. Either fixed block size or variable block size may b
49、e defined. A block type value of 00h shall be used to indicate that the payload area does not contain an HD-SDTI payload. 1.7.1 Fixed block type B7 and B6 form the prefix to define the fixed block data structure as follows. B7 B6 Fixed block size without error correction control (ECC): 0 0 Fixed block size with ECC: 0 1 Where the fixed block includes ECC, the ECC is contained within the fixed block data and the type of ECC shall be defined by the application. 10 Rec. ITU-R BT.1577 The possible segmentation of the fixed block size and the v
