1、 Copyright 2015 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 3 Barker Avenue, White Plains, NY 10601 (914) 761-1100 Approved March 27, 2015 The attached document is a Registered Disclosure Document prepared by the proponent identified below. It has been examined by the appropriate SMPTE
2、 Technology Committee and is believed to contain adequate information to satisfy the objectives defined in the Scope, and to be technically consistent. This document is NOT a Standard, Recommended Practice or Engineering Guideline, and does NOT imply a finding or representation of the Society. Error
3、s in this document should be reported to the proponent identified below, with a copy to engsmpte.org. All other inquiries in respect of this document, including inquiries as to intellectual property requirements that may be attached to use of the disclosed technology, should be addressed to the prop
4、onent identified below. This document defines the Dolby-E mapping onto AES-3 according to SMPTE ST 337 and SMPTE ST 339, and to be a proper reference in SMPTE ST 338 for code point 28. Proponent contact information: Jeffrey Riedmiller Dolby Laboratories 100 Potrero Avenue San Francisco, CA 94103 USA
5、 Email: JCR Page 1 of 10 pages SMPTE RDD 33:2015 SMPTE REGISTERED DISCLOSURE DOCUMENT Format for Non-PCM Audio and Data in AES3 Dolby-E Data Type SMPTE RDD 33:2015 Page 2 of 10 pages Table of Contents Page 1 Scope 3 2 Normative References 3 3 Definitions and Acronyms . 3 3.1 Definitions 3 3.2 Acrony
6、ms . 4 4 Dolby E . 4 4.1 Overview 4 4.2 burst_preamble 5 4.3 data_type identifier 5 4.4 data_type_dependent 5 4.5 data_stream_number 5 4.6 Dolby E burst_payload 5 4.7 Dolby E Sampling Frequency 5 4.8 Dolby E Reference Point . 5 4.9 Dolby E Standard Repetition Rate 5 4.10 Dolby E Standard Decode Late
7、ncy . 6 4.11 Dolby Reference Position 6 4.12 Dolby E Guard Band 8 4.13 Use of Pause Data Bursts between Dolby E Data Bursts . 9 Annex A Bibliography (Informative) 10 SMPTE RDD 33:2015 Page 3 of 10 pages 1 Scope This Registered Disclosure Document (RDD) describes how Dolby E data rate reduced (non-PC
8、M) audio streams are packed into an AES3 data stream, following the methods described by SMPTE ST 337. The Dolby E data type is identified by a data type number listed in SMPTE ST 338 and carried in the burst information word of the data burst preamble. The RDD describes how the Dolby E data is pack
9、ed into the AES3 data stream. Note: “Dolby“, and the double -D symbol are trademarks of Dolby Laboratories. 2 Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this recommended practice. At the time of publication, the edi
10、tions indicated were valid. All standards are subject to revision, and parties to agreements based on this recommended practice are encouraged to investigate the possibility of applying the most recent edition of the standards indicated below. Dolby Laboratories, “Dolby E Professional Encoder Develo
11、pment Manual” SMPTE ST 337:2015, Format for Non-PCM Audio and Data in an AES3 Serial Digital Audio Interface SMPTE ST 339:2015, Format for Non-PCM Audio and Data in AES3 Generic Data Types 3 Definitions and Acronyms 3.1 Definitions 3.1.1 Latency Delay time of an external audio decoder to decode a Do
12、lby E data burst, defined as the sum of two values; the receiving delay time and the decoding delay time. 3.1.2 Fractional frame rates Dolby E supports two fractional audio frame rates. These frame rates are written in shorthand notation, as specified in Table 1. Table 1 Shorthand notation for fract
13、ional frame rates Fractional Dolby E audio frame rate (fps) Shorthand version 24 x 1 000 / 1 001 23.976 30 x 1 000 / 1 001 29.97 Note: Dolby E is usable with video systems running at other frame rates, such as 60/1.001 fps, by using the methods documented in SMPTE RDD 19. SMPTE RDD 33:2015 Page 4 of
14、 10 pages 3.2 Acronyms 3.2.1 fps frames per second 3.2.2 PCM Pulse Code Modulation 4 Dolby E 4.1 Overview Dolby E coded audio, as defined in the Dolby E Professional Encoder Development Manual, shall be transported in an AES3 data stream as a series of Data Bursts. Each Data Burst shall start with a
15、 Burst Preamble as defined by SMPTE ST 337, containing information about the Burst Payload, which shall follow the Burst Preamble. The Burst Payload shall consist of a Dolby E frame. The Burst Payload shall be followed by enough padding words (which shall be PCM zeros, or digital silence) to make th
16、e resulting Data Burst duration exactly match the duration in samples of baseband (PCM) audio that the Dolby E coded audio represents. The resulting Data Bursts shall be placed in the audio sample word/aux data fields of AES3 subframes at regular intervals in either the frame or subframe mode (see S
17、MPTE ST 337, Section 5). Data Bursts shall be placed in the AES3 transport, using either 16, 20, or 24 bits of the available data space. A single Dolby E Frame shall form the Burst Payload, as shown in Figure 1. P aD o l b y E D a t a B u r s t2 0 0 2 A u d i o S a m p l e p e r i o d s ( 4 1 . 7 m
18、s 4 8 k H z )B u r s t P r e a m b l eB u r s t p a y l o a dT h e R e f e r e n c e P o i n t i s b i t 0 o f t h e P a s y n c w o r dS y n c W o r dD o l b y E M e t a d a t a + A u d i oD o l b y E F r a m e r e p r e s e n t i n g 2 0 0 2 s a m p l e s o f a u d i oD o l b y E F r a m eP b P c
19、P d P aD o l b y E D a t a B u r s t2 0 0 2 A u d i o S a m p l e p e r i o d s ( 4 1 . 7 m s 4 8 k H z )B u r s t p a y l o a dD o l b y E F r a m eP b P c P dP a d d i n g ( s i l e n c e ) P a d d i n g ( s i l e n c e )D o l b y E G u a r d B a n dD o l b y E G u a r d B a n dFigure 1 Structure
20、of a Dolby E Data Burst (Dolby E frame rate = 23.976 fps) SMPTE RDD 33:2015 Page 5 of 10 pages 4.2 burst_preamble The Pc word (burst_info value) of the burst_preamble carries the data_type identifier, the data_type_dependent and the data_stream_number information (see SMPTE ST 337, Table 7). 4.3 dat
21、a_type identifier The data_type identifier shall be set to 28. 4.4 data_type_dependent The data_type_dependent bits shall be set to 0. 4.5 data_stream_number The data_stream_number shall be set to 0h. 4.6 Dolby E burst_payload A Dolby E bit stream consists of a sequence of Dolby E frames. The Dolby
22、E burst-payload shall consist of a single Dolby E frame. The length of the Dolby E data-burst will depend on the encoded bit rate (which determines the Dolby E frame length). 4.7 Dolby E Sampling Frequency When Dolby E data are conveyed by the AES3 interface, the AES3 frame frequency shall be equal
23、to the sampling frequency of the Dolby E encoded audio. Bits 24-27 of the channel status word shall indicate the sampling frequency. 4.8 Dolby E Reference Point The reference point of a Dolby E data burst is defined as bit 0 of the burst_preamble, i.e. the start of the data burst (Pa = sync word 1).
24、 4.9 Dolby E Standard Repetition Rate Dolby E data bursts are nominally placed in the AES3 interface such that the reference points of consecutive data bursts occur at a standard repetition rate. The standard repetition rate is defined as the number of AES3 frames that correspond to one video frame
25、of an associated video reference signal corresponding to the Dolby E encoded frame rate. Table 2 shows the relationship between the Dolby E frame rate and the number of AES3 frames that correspond to each frame rate at a sampling frequency of 48 kHz. Table 2 Dolby E standard repetition rate for each
26、 frame rate Dolby E Frame Rate (fps) Dolby E Standard Repetition Rate 23.976 2,002 AES3 frames 24 2,000 AES3 frames 25 1,920 AES3 frames 29.97 1,601.6 AES3 frames 30 1,600 AES3 frames SMPTE RDD 33:2015 Page 6 of 10 pages At a frame rate of 29.97 fps frame rate, the defined repetition rate is not an
27、integer number of AES3 frames due to the relationship of AES3 frames to video frames. In practice the spacing between data bursts will vary between 1,601 and 1,602 samples. For Dolby E bit streams that have a frame rate of 29.97 fps, it is important to maintain precise alignment with the correspondi
28、ng video over 8,008 AES3 frames, which corresponds to five video frames at 29.97 fps. This is generally accomplished by repeating a decoded PCM output sample count of 1,602/1,601/1,602/1,601/1,602 every five frame periods. 4.10 Dolby E Standard Decode Latency The Dolby E reference decode latency is
29、defined as the time equivalent to one Dolby E frame period at the Dolby E frame rate. This means that a reference decoder would output the first PCM sample encoded in a Dolby E frame exactly one Dolby E frame period after the first bit of the frame is received by the decoder. Table 3 shows the Dolby
30、 E standard decode latency for each frame rate. Table 3 Dolby E standard decode latency for each frame rate Dolby E Frame Rate (fps) Dolby E standard decode latency 23.976 2,002 AES3 frames 41.7 ms 24 2,000 AES3 frames 41.67 ms 25 1,920 AES3 frames 40 ms 29.97 1,601.6 AES3 frames 33.37 ms 30 1,600 A
31、ES3 frames 33.33 ms 4.11 Dolby E Reference Position The Reference Position of a Burst Payload is defined by the relationship of the decoded audio to the associated video signal. A Burst Payload is in the Reference Position when the decoded audio from that Burst Payload is in sync with the associated
32、 video. The Dolby E reference position is defined in relation to the video frame that corresponds to the Dolby E-encoded audio samples. A Dolby E data burst is defined as occupying the reference position in the AES3 stream if at least one of the following requirements is met: 1. Ideal reference posi
33、tion: The ideal reference position occurs in the AES3 stream at the first AES3 frame after the start of the defined video line of a video reference signal that corresponds to the Dolby E frame. The ideal Dolby E reference line position is specified in the “Ideal Position 80S” column of Table 4. 2. A
34、cceptable reference position: the Dolby E data burst is considered to be in an acceptable reference position if the reference position is located 80 microseconds from the ideal position. The acceptable reference positions are specified in the “Ideal Position -80S” and “Ideal Position +80S” column of
35、 Table 4. 3. Safe reference position: the Dolby E data burst is considered to be in a safe position (meaning no Dolby E frame data will be corrupted at a switch) if the reference point is within the following range: a. Earliest valid position: the reference point is immediately after the defined vid
36、eo switch point, as specified in the Earliest Valid Position column of Table 4. b. Latest valid position: the reference point ensures that the Dolby E frame data ends before the end of the video frame, as specified in the Latest Valid Position column of Table 4. SMPTE RDD 33:2015 Page 7 of 10 pages
37、Table 4 Dolby E reference position per video format Video Format Frame Rate (fps) Total Number of Lines Earliest Valid Position Ideal Position Latest Valid Position -80S 80S +80S Line S Line S Line S Line S Line S 625/50/i 25 625 8 450 11 650 12 730 13 810 30 1860 525/59.94/i 29.97 525 12 510 13 610
38、 14 690 16 770 26 1400 Dolby Black/23.98 23.98 693 10 390 18 890 20 970 21 1050 63 3610 Dolby Black/24 24 625 9 390 17 890 18 970 19 1050 58 3610 Dolby Black/30 30 500 11 510 13 610 14 690 15 770 26 1530 1920x1080/60/i 30 1125 18 510 21 610 24 690 26 770 52 1530 1920x1080/59.94/i 29.97 1125 18 510 2
39、1 610 24 690 26 770 48 1400 1920x1080/50/i 25 1125 13 450 19 650 21 730 23 810 53 1860 1920x1080/48/i 24 1125 11 390 25 890 27 970 29 1050 98 3610 1920x1080/47.97/i 23.98 1125 11 390 25 890 27 970 29 1050 98 3610 1920x1080/60/p 30 1125 35 510 42 610 47 690 52 770 104 1530 1920x1080/59.94/p 29.97 112
40、5 35 510 42 610 47 690 52 770 95 1400 1920x1080/50/p 25 1125 26 450 37 650 42 730 46 810 105 1860 1920x1080/30/p 30 1125 18 510 21 610 24 690 26 770 52 1530 1920x1080/29.97/p 29.97 1125 18 510 21 610 24 690 26 770 48 1400 1920x1080/25/p 25 1125 13 450 19 650 21 730 23 810 53 1860 1920x1080/24/p 24 1
41、125 11 390 25 890 27 970 29 1050 98 3610 1920x1080/23.98/p 23.98 1125 11 390 25 890 27 970 29 1050 98 3610 1280x720/60/p 30 750 23 510 28 610 32 690 35 770 69 1530 1280x720/59.94/p 29.97 750 23 510 28 610 32 690 35 770 63 1400 1280x720/50/p 25 750 17 450 25 650 28 730 31 810 70 1860 1280x720/30/p 30
42、 750 12 510 14 610 16 690 18 770 35 1530 1280x720/29.97/p 29.97 750 12 510 14 610 16 690 18 770 32 1400 1280x720/25/p 25 750 9 450 13 650 14 730 16 810 35 1860 1280x720/24/p 24 750 8 390 17 890 18 970 19 1050 65 3610 1280x720/23.98/p 23.98 750 8 390 17 890 18 970 19 1050 65 3610 S = Microseconds The
43、 Dolby E data burst shall be coincident in time with the video frame that corresponds to the audio samples coded within the Dolby E frame. Note: Requirements 1 and 2 reference a defined video reference signal. Requirement 3 references a content video signal that may be the video reference signal. If
44、 not, it is assumed that the Dolby E burst is locked to the video reference signal. See SMPTE RDD 19 for additional guidance regarding use of Dolby E with video systems operating at frame rates higher than 30 Hz. Note: Requirements 1 and 2 meet the basic Dolby E phase synchronization requirement for
45、 AES3 transport applications. Requirement 4 defines the reference location for lip sync. SMPTE RDD 33:2015 Page 8 of 10 pages 4.12 Dolby E Guard Band To allow a video stream to be cut-edited or switched while ensuring that the accompanying Dolby E data remains error-free, a period of AES3 null data
46、precedes the Dolby E data burst. This null data is referred to as the Dolby E guard band. The guard-band location and duration is chosen so that Dolby E data is not present on the AES3 interface during video lines in which switches or edits will occur, and so that some delay (a few lines) can be tol
47、erated in the audio path. The portion of the guard band that precedes the Dolby E data burst begins at the AES3 sample that is aligned to the SMPTE RP 168 reference point, and ends at the start of the Dolby E data burst at the Dolby E reference position (see Table 4). The size and location of the gu
48、ard band are determined by the synchronization requirements specified in Section 5.7, and the size of the encoded Dolby E frame. The total duration of the Dolby E guard band for each frame rate is shown in Table 5. Table 5 Dolby E guard band duration Dolby E Frame Rate (fps) Total guard band duratio
49、n (AES3 frames) 23.976 100 24 100 25 96 29.97 80 30 80 Figure 2 shows the alignment of a Dolby E data burst from a 25 fps Dolby E stream, and a 625 line, 25 fps video stream. In this case, the Dolby E reference position is at the Ideal Position as specified in Table 4. P aD o l b y E D a t a B u r s t1 9 2 0 A u d i o S a m p l e p e r i o d s ( 4 0 m s 4 8 k H z )B u r s t P r e a m b l eB u r s t p a y l o a dD o l b y E F r a m eP b P c P d P aD o l b y E D a t a B u r s t1 9 2 0
