SMPTE ST 355M-2001 Television - Format for Non-PCM Audio and Data in AES3 - KLV Data Type.pdf

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1、SMPTE STANDARD This standard describes a means for packing SMPTE metadata andor essence encoded in the SMPTE 336M KLV protocol into AES3 serial digital streams. A strong interest exists to carry audio/visual data, metadata, andor essence within the same digital SMPTE 355M-2001 Meaning Reserved, shal

2、l be set to O000 d ata3 yp e-de p e nde n t bit number 0-3 4 key-f lag for Television - - Format for Non-PCM Audio and Data in AES3 - KLV Data Type 1 Scope This standard specifies data type specific format re- quirements for SMPTE 336M (KLV) data bursts car- ried within an AES3 interface according t

3、o SMPTE 337M. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this

4、 standard are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. 0 SMPTE m6M-2001 , Television - Data Encoding Protocol using Key-Length-Value SMPTE 337M-2000, Television - Format for Non- PCM Audio and Data in AES3 Serial Digital Audio I

5、nte rface SMPTE 338M-2000, Television - Format for Non- PCM Audio and Data in AES3 - Data Types SMPTE RP 210.1-2001 , Metadata Dictionary 3 Introduction Page 1 of 7 pages stream. The use of one data stream facilitates delivery and synchronization of the overall multimedia presen- tation to the consu

6、mer. Metadata is classified as information about the content or essence. An example of metadata is information such as camera angle, scene identifier, or propetty rights. Other essence is supplemental content to the audio and video such as closed captioning, sports statistics, or hyperiinked adverti

7、sements. 4 SMPTE 336M (KLV) burst-preamble The SMPTE 337M protocol describes an interface format for the transport of non-PCM audio or data, using the AES3 serial digital audio interface. The SMPTE 336M (KLV) data type is provided for the transmission of non-PCM data formatted according to the SMPTE

8、 336M (KLV) protocol. 4.1 data-type The data-type shall have a value of 27. 4.2 data-type-dependent The burstjreamble for a SMPTE 336M (KLV) type data burst shall include a data-type-dependent field encoded as shown in table 1. Table 1 - Values of data-type-dependent field for SMPTE 336M (KLV) data

9、type CopyrM82001 by THESOCIETYOF MOTION PICTURE ANDTELEVISION ENGINEERS 595 W. Hartsdaie Ave., White Plains, NY lW7 (914) 761-1 100 Approved April 19,2001 SMPTE 355M-2001 I 4.3 key-flag When this flag is set to 1, a universal label key as defined in SMPTE 336M (KLV) shall be present at the beginning

10、 of the burst-payload indicating that the data burst contains the start of a KLV packet. When this flag is set to O, no key shall be present in the burstgayload indicating that the data burst is a con- tinuation of a KLV packet. 5 SMPTE 336M (KLV) burst-payload KLV data packets shall be placed into

11、the burstgay- load such that the beginning of the KLV packet (start- ing with a universal label data key) shall be present at the beginning of a burstgayload immediately follow- ing preamble word Pd (length-code). The key-flag in the data-type-dependent field of this data burst shall be set to 1 ind

12、icating the data burst contains the start of a KLV packet. The KLV packet shall be segmented into 16-, 20-, or 24-bfl data words for mapping into the AES3 subframes of the burstgayload depending on the data-mode specified in the burstgreamble. The first bit of the UL data key shall be placed in time

13、 slot 27 of the first AES3 subframe of the burstgayload. Any unused AES time slots in the last AES3 sub- frame of the burstgayload shall be filled with O as specified in SMPTE 337M. If the size of the KLV packet exceeds the size of the burstgayload in this data burst, the KLV packet shall be continu

14、ed in subsequent data bursts of the same data-stream-number with the key-flag set to O in the additional data bursts. In this way, a single KLV packet may span muitiple data bursts. Individual data bursts shall contain no more than one KLV packet. Other standards or recommended practices may specify

15、 additional formatting requirements for data bursts for specific data types carried within the KLV packet. Page 2 of 7 pages b - SMPTE 3SM-2001 Annex A (informative) Organization of references The organization of SMPTE standards and recommended practices addressing the coding of individual data item

16、s such as essence and metadata are illustrated in figure A.1. NO single standard can contain all of the information needed to describe and encode all data. The encoding protocol standard (SMPTE 336M) and the metadata dictionary document (SMPTE RP 210) form the SMPTE normative standards for defining

17、metadata and its coding. Informative SMPTE docu- ments supplement the standards for encoding with exam- ples and administrative instructions on managing the data standardization and registration process. Essence Metadata Type i. Lpplication Layer or Essence Metadata Advanced Classes ” Other Meadata

18、Dictionaries Protocol Layer Transport Layer Other Transpo IL I Standards Figure A.l - Organization of references Page 3 of 7 pages SMPTE 355M-2001 Pa Pb Pc Pd Annex B (informative) KLV data packets ULDataKey ValueLength Value KLV data packetsconsist of a 16-octet (byte) universal label data key segm

19、ent (key), a length segment, and a value segment. The key segment consists of a number of subseg- ments as shown in figure B.l. When conveying KLV data on the AES3 interface, the KLV packet is first mapped into the burst-payload section of one or more data bursts as defined in SMPTE 337M and this st

20、andard (see figure 8.2). Should the length of the KLV packet exceed the size of the burst-payload section of a data burst, then the KLV packet is continued in subsequent data bursts (see keyflag designator above). The data bursts containing the KLV packets must then be subsegmented and mapped into A

21、ES3 subframes. AES3 subframes consist of 32 bits (time slots) of which 16, 20, or 24 bits may be used to carry data, depending on the data mode that is selected. This mapping is illustrated in figure 8.3. As shown, the most significant bit (MSB) of each 16-, 20-, or 24-bit subsegment will map to tim

22、e slot 27 of the AES subframe. The least significant bit (LSB) will map to time slot 12, 8, or 4 depending on the data mode. Figures 8.4-8.6 illustrate a detailed mapping of the burst-preamble and burst-payload segments to AES3 time slots. Since the burstjreamble is defined to always occupy four AES

23、3 subframes independent of the data-mode, the start of the burst-payload and, therefore, the start of the KLV data will always begin in time slot 27 of an AES3 subframe. Note that in the 20-bit mode, some bytes will be split between AES3 subframes with 4 bits in one AES3 subframe and 4 bits in the f

24、ollowing AES3 subframe (as shown in figure B.5). 1- Value Length Octets -FI - Variable - Variable Length - - fi octets -Y- - UL Data Key - 16 Octets UL Header UL Designa tors Figure 6.1 - SMPTE KLV data packet Data Elem en t Tag burst preamble Figure B.2 - KLV mapping to AES3 data bursts Page 4 of 7

25、 pages SMPTE 355M-2001 u MSB audio sample word LSB AUX Preamble . sa sa sa sa MSB hrstg.ylosd byte 2 LSB MSB buntgsylond byte 3 LSB 16 bit mode ,md 20 bit mode X LSB 4 24 bit mode MSB O - MSB bomtgsybad byte II LSB Figure 8.3 - Mapping data burst segments to AES3 subframes X b- AES3meslots -4 27 26

26、25 24 23 22 21 20 i9 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 Pa I F 1 8 I 7 I 2 I X I Ff I I F I X Pb 4 E 1 Pd MSB length-code LSB X IMSB burstg.ykad byte O LSB IMSB buntprylaid byte I LSB 1 X Figure 8.4 - Mapping data burst segments to AES3 time slots (1Sait mode) Page 5 of 7 pages SMPE 355M-20QI I

27、6 F Pa Pb Pc Pd I I X 8 7 2 d.ta-rhrim# data-yp-dependcat cf mode dita-ypc O X * AES3 burst- payload Pb Figure B.5 - Mapping data burst segments to AES3 time slots (20-bit mode) I I A 5 4 E 1 F b-. AES3meslots -4 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 Pa 9 I 6 I F I 8 I 7

28、I 2 177 Pc Pd I preamble drtn-stmm# &ta-type-dependent cf mode &ta_type O MSB length-code MSB buntjayload byte O LSB IMSB bmt8loid byte 1 LSB MSB buntpnybad byte 2 LSB subframes burst- (MSB buntgayloid byte 3 LSB (MSB buntpiyload byte 4 LSB (MSB buirstgiybad byte 5 LSB me. - MSB Figure B.6 - Mapping

29、 data burst segments to AES3 time slots (24-bit mode) Page 6 of 7 paw SMPTE 355M-2001 Pd MSB Iength-code* LSB Annex C (informative) 0 Example X As an example of mapping KLV packets into the AES3 interface, consider a KLV packet with a key as shown in figure C.1. In this example, the KLV packet is to

30、 be carried in the AES3 interface in the 16-bit mode in a single AEC3 data burst identified as stream #O. Therefore, the values of the fields in the burst-info header of the AES3 burstjreamble are: MSB buntgayload word n LSB I data-stream-number = O data-type-dependent = O x 1 O (key-flag is set err

31、or-flag = O data-mode 3: O data-type = O x 18 indicating key is present) Therefore, the mapping of the KLV packet to the AES3 data burst is as shown in figure C.2. 06.OE.2B.34.01 .O1 .O1 .01.07.09.02.02.02.00.00 Figure C.1- Example universal label data key b- AES3 time slob 27 26 25 24 23 22 21 20 1

32、9 18 17 16 15 14 13 12 II 10 9 8 7 6 5 4 OXFB721 1 1 111 o o 010 1 1 If0 o 1 01 x I It qo o ob0 o o ololo Oll 1 o 1 11 X OXO6qO o/o o o 1 I o o o o o 1 1 1 o1 X Ox2B34 0 $ 10101100110100 X / *o kcy-flae I burst- preamble I AEs3 su bframes , burst- payload I *Length-code indicates the length of burst

33、jayload (in bits) which in this example will equal the size of the entire KLV packet. Figure C.2 - Example mapping of KLV data burst to AES3 time slots Annex D (informative) Bibliography AES3-1992, Digital Audio Engineering - Serial Transmis- sion Format for Two-Channel Linearly Represented Digital ANSIISMPTE 298M-1997, Television - Universal Labels for Unique Identification of Digital Data Page 7 of 7 pages