1、 Recommendation ITU-R BT.1305-1(03/2010)Digital audio and auxiliary data as ancillary data signals in interfaces conformingto Recommendations ITU-R BT.656and ITU-R BT.799BT SeriesBroadcasting service(television)ii Rec. ITU-R BT.1305-1 Foreword The role of the Radiocommunication Sector is to ensure t
2、he rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory and policy functions of the
3、Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R/ISO/IEC referenced in Ann
4、ex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO/IEC and the ITU-R patent
5、information database can also be found. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT Broadcasting service (telev
6、ision) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fixed-satellite and fixed ser
7、vice systems SM Spectrum management SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Publication Geneva, 2010 ITU 201
8、0 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R BT.1305-1 1 RECOMMENDATION ITU-R BT.1305-1*Digital audio and auxiliary data as ancillary data signals in interfaces conforming to Recommendations ITU-R BT.656
9、and ITU-R BT.799 (Question ITU-R 39/6) (1997-2010) Scope This Recommendation defines the mapping rules for the carriage of an AES/EBU bit stream as defined in Recommendation ITU-R BS.647 over horizontal ancillary data space of serial digital interfaces conforming to Recommendation ITU-R BS.656 and I
10、TU-R BT.799. The data carried in the bit stream may be two channels of periodically sampled and linearly represented digital audio data, or other data formatted to fit the payload space of the AES/EBU bit stream. The ITU Radiocommunication Assembly, considering a) that many countries are installing
11、digital television production facilities based on the use of digital video components conforming to Recommendations ITU-R BT.601 and ITU-R BT.656; b) that there exists the capacity within a signal conforming to Recommendation ITU-R BT.656 for additional data signals to be multiplexed with the video
12、data signal; c) that there are operational and economic benefits to be achieved by the multiplexing of ancillary data signals with the video data signal; d) that the operational benefits are increased if a minimum of different formats are used for ancillary data signals; e) that ancillary data signa
13、ls embedded in the serial interface is already in widespread use; f) that Recommendation ITU-R BS.647 specifies an interface (commonly known as the Audio Engineering Society/European Broadcasting Union (AES/EBU) interface) for the serial transmission of two channels of digital audio and auxiliary si
14、gnals, recommends 1 that, for the inclusion of digital audio and auxiliary data as ancillary data signals in interface signals conforming to Recommendations ITU-R BT.656 and ITU-R BT.799, the specification in Annex 1 should be used; *Radiocommunication Study Group 6 made editorial amendments to this
15、 Recommendation in 2007 in accordance with Resolution ITU-R 44. 2 Rec. ITU-R BT.1305-1 2 that compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendati
16、on is achieved when all of these mandatory provisions are met. The words “shall” or some other obligatory language such as “must” and the negative equivalents are used to express requirements. The use of such words shall in no way be construed to imply partial or total compliance with this Recommend
17、ation. Annex 1 Digital audio and auxiliary data as ancillary data signals 1 Introduction This specification defines the mapping of digital audio and auxiliary data conforming with Recommendation ITU-R BS.647, the signal may also contain non PCM data, and associated control information into the ancil
18、lary data space of serial digital video conforming to Recommendations ITU-R BT.656 and ITU-R BT.799. Non-PCM data may be present as part of the AES/EBU bit-stream payload. Audio sampled at 48 kHz and clock locked (isochronous) to video is the preferred implementation for intra-studio applications. A
19、s an option, this specification supports AES/EBU audio at isochronous or asynchronous sampling rates from 32 to 48 kHz. The minimum, or default, operation of this specification supports 20 bits of audio data as defined in 3.5. As an option, this specification supports 24-bit audio or 4 bits of AES/E
20、BU auxiliary data as defined in 3.10. This specification provides a minimum of 2 audio channels and a maximum of 16 audio channels based on available ancillary data space. Audio channels are transmitted in pairs combined, where appropriate, into groups of 4. Each group is identified by a unique anci
21、llary data ID. Several modes of operation are defined, identified by letter suffixes to facilitate convenient identification of interoperation between equipment with various capabilities. The default form of operation is 48 kHz isochronous audio sampling carrying 20 bits of AES/EBU audio data and de
22、fined in a manner to ensure reception by all equipment conforming to this specification. 2 References Recommendation ITU-R BT.656: Interface for digital component video signals in 525-line and 625-line television systems operating at the 4:2:2 level of Recommendation ITU-R BT.601. Recommendation ITU
23、-R BS.647: A digital audio interface for broadcasting studios. Recommendation ITU-R BT.799: Interface for digital component video signals in 525-line and 625-line television systems operating at the 4:4:4 level of Recommendation ITU-R BT.601. Recommendation ITU-R BT.1364: Format of ancillary data si
24、gnals carried in digital component studio interfaces. Rec. ITU-R BT.1305-1 3 3 Definitions The following definitions apply to terms used in this Recommendation: 3.1 AES/EBU audio All the data, audio and auxiliary information, associated with an AES/EBU bit stream is defined by Recommendation ITU-R B
25、S.647. 3.2 AES/EBU frame Two AES/EBU subframes, one with audio data for channel 1 followed by one with audio data for channel 2. 3.3 AES/EBU subframe All data associated with one AES/EBU audio sample for one channel in a channel pair. 3.4 Audio control packet An ancillary data packet occurring once
26、in a field and containing data used in the operation of optional features of this specification. 3.5 Audio data 23 bits: 20 bits of AES/EBU audio associated with one audio sample, not including AES/EBU auxiliary data, plus the following 3 bits: Sample Validity (V-bit), Channel Status (C-bit), User D
27、ata (U-bit). 3.6 Audio data packet An ancillary data packet as defined in Recommendation ITU-R BT.1364 containing audio data for one or two channel pairs (two or four channels). An audio data packet may contain audio data for 1 or more samples associated with each channel. 3.7 Audio frame number A n
28、umber, starting at 1, for each frame within the audio frame sequence. For the example in 3.8 the frame numbers would be 1, 2, 3, 4, 5. 3.8 Audio frame sequence The number of video frames required for an integer number of audio samples in isochronous operation. As an example: the audio frame sequence
29、 for isochronous 48 kHz sampling in a 525-line (29.97 frame/s) system is 5 frames and for a 625-line (25 frame/s) system is 1 frame. 3.9 Audio group Consists of one or two channel pairs which are contained in one ancillary data packet. Audio groups are numbered 1 through 4. Each audio group has a un
30、ique ID as defined in 12.2. 3.10 Auxiliary data 4 bits of AES/EBU audio associated with one sample defined as auxiliary data by Recommendation ITU-R BS.647. The 4 bits may be used to extend the resolution of audio samples. 4 Rec. ITU-R BT.1305-1 3.11 Channel pair Two digital audio channels, generall
31、y derived from the same AES/EBU audio source. 3.12 Extended data packet An ancillary data packet containing auxiliary data corresponding to, and immediately following, the associated audio data packet. 3.13 Sample pair Two samples of AES/EBU audio as defined in 3.1. 3.14 Isochronous audio Audio is d
32、efined as being clock isochronous with video if the sampling rate of audio is such that the number of audio samples occurring within an integer number of video frames is itself a constant integer number, as in the following examples: Audio sampling rate (kHz) Samples/frame, 29.97 frame/s video Sampl
33、es/frame, 25 frame/s video 48.0 8008/5 1920/1 44.1 147147/100 1764/1 32.0 16016/15 1280/1 NOTE 1 The video and audio clocks must be derived from the same source since simple frequency synchronization could eventually result in a missing or extra sample within the audio frame sequence. 4 Overview and
34、 levels of operation 4.1 Configurations Audio data derived from one or more AES/EBU frames and one or two channel pairs is configured in an audio data packet as shown in Fig. 1. Generally, both channels of a channel pair will be derived from the same AES/EBU audio source, but this is not essential.
35、The number of samples per channel contained in one audio data packet will depend on the distribution of the data in a video field. As an example, the ancillary data space in some television lines may carry three samples, some may carry four samples. Other values are possible. NOTE 1 Some existing eq
36、uipment may transmit other sample counts, including zero. Receiving equipment should handle correctly sample counts from zero to the limits of ancillary data space. Rec. ITU-R BT.1305-1 5 1305-01Y Channel 2 Channel 1 Channel 2 Channel 1 Channel 2ZYXYSubframe 1 Subframe 2Frame 0 Frame 1Frame 191AES c
37、hannel-pair 2Y Channel 2 Channel 1 Channel 2 Channel 1 Channel 2YXYSubframe 1 Subframe 2Frame 0 Frame 1Frame 191 Frame 3ZAES channel-pair 120 bits sample dataSubframe 2 (channel 2)AES channel-pair 1Auxiliary data 4 bitsPreamble X, Y or Z, 4 bitsAudio sample validityUser bit dataAudio channel statusS
38、ubframe parityAES Subframe 32 bitsDataIDDatablock No.DatacountAES1, channel 1,channel 1X, X+1, X+2AES1, channel 2,channel 2X, X+1, X+2AES2, channel 1,channel 3X, X+1, X+2Checksum4 bits of data contained in 1extended data packet wordAudio data packetPrecedes associated extended data packet20 + 3 bits
39、 of data ismapped into 3 ANC wordsDataIDDatablock No.DatacountChecksumAUX AUX AUX AUX AUX AUXData header000 3FF 3FF1 word contains theauxiliary data for 2 samplesExtended data packetFollows associated audio data packet2 groups of 4 bitsmapped into 1 wordFIGURE 1Relation between AES data and audio/ex
40、tended data packets6 Rec. ITU-R BT.1305-1 4.2 Packet types Three types of ancillary data packets to carry AES/EBU audio information are defined. The audio data packet carries all the information in the AES/EBU bit stream excluding the auxiliary data defined by Recommendation ITU-R BS.647. The audio
41、data packets must be located in the horizontal ancillary data space on most of the television lines in a field. An audio control packet is transmitted once per field, is optional for the default case of 48 kHz isochronous audio (20 or 24 bit) but is required for all other modes of operation. Auxilia
42、ry data is carried in an extended data packet corresponding to, and immediately following, the associated audio data packet. Data IDs (see 12 to 14) are defined for four separate packets of each packet type. This allows for up to eight channel pairs. In this specification, the audio groups are numbe
43、red 1 to 4 and the channels are numbered 1 to 16. Channels 1 to 4 are in group 1, channels 5 to 8 are in group 2, and so on. If extended data packets are used they are included on the same video line as the audio data packet which contains data from the same sample pair. The extended data packet fol
44、lows the audio data packet and contains two 4-bit groups of auxiliary data per ancillary data word as shown in Fig. 1. 4.3 Degrees of compliance It is not essential that an equipment should have all the possibilities of this Recommendation fully implemented. To indicate the extent to which an equipm
45、ent may implement these possibilities a suffix letter is added. The suffix letters and the corresponding levels of implementation are shown in Table 1. TABLE 1 Levels of implementation Level Support A Isochronous audio at 48 kHz, 20-bit audio data packets. (Distribution of samples on the television
46、lines for level A specifically follows the uniform sample distribution as required by 9.1 in order to ensure interoperation with receivers limited to level A operation) B No longer in use C Isochronous audio at 48 kHz, audio and extended data packets D Asynchronous audio (48 kHz implied, other frequ
47、encies if so indicated) E 44.1 kHz audio F 32 kHz audio G 32-48 kHz continuous sampling rate range H Audio frame sequence (see 14.4) I Time delay tracking J Non-coincident Z-bits in a channel pair Rec. ITU-R BT.1305-1 7 Examples of compliance nomenclature: A transmitter that supports only 20-bit 48
48、kHz isochronous audio conforms to level A. (Transmitted sample distribution is expected to conform to 9.) A transmitter that supports 20-bit and 24-bit 48 kHz isochronous audio conforms to levels A and C. (In the case of level A operation the transmitted sample distribution is expected to conform to
49、 9 while a different sample distribution may be used when it is in operation conforming to level C.) A receiver which can only accept 20-bit 48 kHz isochronous audio and requiring level A sample distribution conforms to level A. A receiver which accepts and utilizes the 24-bit data conforms to level C. Equipment that supports only asynchronous audio and only at 32 kHz, 44.1 kHz and 48 kHz conforms to levels D, E and F. 5 Use of ancillary data space 5.1 Ancillary space utilized Audio and extended data is located in the digital line blanking between end of a
