1、 Table of contents 1 Scope 2 Normative reference 3 Glossary of acronyms, terms and data types 4 Introduction 5 Application 6 Header metadata specification 7 MXF file interchange: Essence container issues Annex A Bibliography 1 Scope This standard defines operational pattern 2b for the exchange of an
2、 MXF file which represents a playlist of ganged (synchronized) essence containers. The essence containers may be internal or external to the file. This standard defines the operating restrictions, structural metadata objects and individual attributes that shall be applied to the MXF file format spec
3、ification to achieve interoperability when exchanging an MXF file as a playlist of ganged essence containers. Operational pattern 2b is intended to meet the requirements of acquisition, storage and interchange applications where more than one essence component is required and it is wished to carry t
4、hese in four or more essence containers. Operational pattern 2b does require the use of body partitions for Internal essence containers. Subdivision of each essence container by using body partitions is optional. 2 Normative reference The following standard contains provisions which, through referen
5、ce in this text, constitute provisions of this standard. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent edition of the stand
6、ard indicated below. SMPTE 377M-2004, Television Material Exchange Format (MXF) File Format Specification 3 Glossary of acronyms, terms and data types The full glossary of acronyms, terms and data types used in the MXF specification is given in the MXF file format specification. It is not repeated h
7、ere to avoid any divergence of meaning. Page 1 of 9 pages SMPTE 393M-2004 Copyright 2004 by THE SOCIETY OF MOTION PICTURE AND TELEVISION ENGINEERS 595 W. Hartsdale Ave., White Plains, NY 10607 (914) 761-1100 Approved September 22, 2004 SMPTE STANDARD for Television Material Exchange Format (MXF) Ope
8、rational Pattern 2b (Play-List Items, Ganged Packages) SMPTE 393M-2004 Page 2 of 9 pages Essence element: An essence container may contain many essence elements interleaved together. An essence element in this document corresponds to a separable part of the interleave which is described by an MXF es
9、sence track, such as a picture track, a sound track or a data track. 4 Introduction This standard defines MXF operational pattern 2b. In SMPTE 377M the properties of the generalized operational patterns are defined. In the MXF engineering guideline, SMPTE EG 41, the concepts of operational patterns
10、and the general conditions for audio-visual material interchange and interoperability are described in outline form. The introductory sections of these documents are not repeated here. 4.1 Operational pattern 2b overview Generalized MXF operational patterns are defined as a combination of the two di
11、mensions as defined in SMPTE 377M. This operational pattern shall be defined as follows: 4.1.1 Item complexity Play-list items: The file contains several concatenated items. Each item is defined by ganged top-level file packages. Each and every material package track shall comprise an identical numb
12、er of SourceClips. The normalized start position of the Nth SourceClip in each and every track shall be the same (normalized Start PositionN= (Start Position of SourceClipN+ Origin of Track)/Edit Rate of Track ). Each material package track shall have an identical duration. 4.1.2 Package complexity
13、Ganged packages: The material package references multiple top-level file packages that are played together against a common output timeline. The ganged essence streams can be regarded as a single stream that represents a continuous recording as indicated in below. These two dimensions are broadly il
14、lustrated in informative figure 1. SMPTE 393M-2004 Page 3 of 9 pages Item Complexity Ganged Packages Single Item Play-list Items Edit Items Alternate Packages Single Package Package Complexity MP FP MP FPs MP FPs MP FPs AND MP FPs MP FPs AND Any MP track from any FP track Each MP SourceClip = entire
15、 FP MP1 MP2 OR MP1 MP2 OR Each MP SourcelCip = entire FP Only 1 MP SourceClip = FP duration Only 1 MP SourcelCip = FP duration MP1 MP2 OR Any MP track from any FP track 1 2 3a b c Figure 1 (informative) Item and package complexity This operational pattern defines an MXF file of play-list items, with
16、 each Item comprising a ganged package as illustrated in the center box of figure 1. 4.2 Material, file and source package relationships This operational pattern has two or more essence containers that are intended to be played synchronously. Each essence container is comprised of either a single es
17、sence element or interleaved essence elements. The essence containers comprise essence stream data that represents a continuous recording as indicated in figure 2. SMPTE 393M-2004 Page 4 of 9 pages Sequence SourceClip SourceClip Track (Sound) Sequence SourceClip Track (Sound) Essence Descriptors e.g
18、. AES audio Sequence (Sound) Track (Sound) SourceClip SourceClip SourceClip Material Package Sequence (Picture) Track (Picture) Sequence (defines duration) SourceClip Track (defines start) SourceClip Essence Descriptor e.g. Tape Descriptor Sequence SourceClip SourceClip Track (Picture) SourceClip So
19、urceClip SourceClip Parallel tracks synchronise the SourceClips. Each SourceClip refers to a different Top-Level File Package. Sequence (duration) SourceClip Track (Picture) Sequence SourceClip Track (Sound) Sequence SourceClip Track (Picture) 3 Top-Level File Packages Each Top-level File Package cr
20、eates an OP2a-like chain. In this example for Picture content 3 Top-Level File Packages Each Top-level File Package creates an OP2a-like chain. In this example for Sound content Source Packages (File or Physical) Giving historical annotation to the essence Essence Descriptors e.g. MPEG video Ganged
21、packages are aligned Figure 2 (informative) Outline of operational pattern 2b 5 Application Operational pattern 2b is an extension of operational patterns 1b and 2a where the output comprises a play-list (contiguous sequence) of multiple ganged (synchronized) essence containers containing the audio-
22、visual items. The ganged essence containers may contain a play-list of shots, a single clip or a single item of program material. Any track of a material package shall only create references to essence containers of a single type. All essence containers shall provide for the continuous decoding of c
23、ontiguous essence elements. The minimum implementation of operational pattern 2b will satisfy the requirement for a concatenation of multiple clips as a program, with metadata support for each clip as well as metadata support for the program as a whole. NOTE An example of the use of this operational
24、 pattern is where a video data stream is carried by one set of essence containers with another (synchronized) set of essence containers carrying the associated audio data stream. The final file may be a play-list of a logo/identifier, followed by the content, followed by some black / silence. This m
25、ay be needed where production of the video and audio are carried out by separate facilities or where audio is produced in both stereo and multi-channel formats. operational pattern 2b constrains all the splice points between SourceClips to be synchronous no “jaggy cut points” are allowed. 5.1 Constr
26、aints A list of general constraints for this operational pattern is given in table 1. SMPTE 393M-2004 Page 5 of 9 pages Table 1 General constraints for operational pattern 2b File Kind MXF “Operational Pattern” 2b: (Play-list of items with multiple ganged essence containers) Role Continuous recordin
27、g, interchange of production items as a bundled play-list of entities. Essence Multiple ganged essence containers. Operational pattern qualifiers apply (see MXF format document SMPTE 377M) Material Packages 1 Number of Material Package SourceClips for each Essence Track 1 Top-level File Packages =4
28、(up to number of material package SourceClips times number of material package tracks) Zero or more top-level file packages may be external to the file. Number of Essence Container Types 1 or more Lower-level Source Packages 0 or more Partition limits None Body Partitions Required. If there are N in
29、ternal essence containers, a file shall have at least N-1 body partitions within it. Index Tables Optional, but recommended Editing Support Simple play-list output Streaming Support According to operational pattern qualifiers (see section 6.4) Note that the “number of material package SourceClips” i
30、n table 1 refers only to essence tracks. Operational patterns are intended to constrain the essence handling of an MXF application, so in the case where the essence is continuous and only the metadata in a file has multiple SourceClips, it is likely that the file is an operational pattern lower than
31、 2b. Note that “1 or more” essence container types is also subject to the continuity of essence condition in 7.2.3. When using the MXF generic container, it is possible that there will be several different essence container labels being signaled in a file (e.g., one for the audio, another for the vi
32、deo). Each and every track is subject to the continuity conditions in 7.2.3. 6 Header metadata specification 6.1 General The structural metadata sets and the normative universal label used to identify this operational pattern are defined in the MXF file format specification document with specific co
33、nstraints and additions detailed below. 6.2 Constraints on the MXF packages The material package shall have more than one SourceClip per essence track. Each top-level file package shall have one track for each essence element in the essence container. The material package SourceClips shall start and
34、 end synchronously across each and every material package track. The material package may have a different start time to the top-level file package start times to allow a change to the initial time code on playback. Lower-level source packages, when present, shall be used to define the historical co
35、ntext of editing. SMPTE 393M-2004 Page 6 of 9 pages 6.3 Universal label for operational pattern 2b The universal label value to define this operational pattern shall be as defined in the table below. Table 2 Value of the MXF operational pattern identification universal label Byte No. Description Val
36、ue (hex) 1-12 Defined in the MXF file format specification operational patterns section 13 Operational Pattern: Item Complexity 02h 14 Operational Pattern: Package Complexity 02h 15 Operational Pattern: Qualifiers (application dependent) (see SMPTE 377M) 16 Operational Pattern: OP2b qualifiers (see
37、Table 3) The meanings of the bytes in this label are specified in the operational pattern section of the MXF file format specification. Bytes 13 and 14 uniquely identify this operational pattern specification, and byte 15 contains generic qualifiers which are defined in the MXF file format specifica
38、tion. Byte 16 contains a qualifier which is specific to this operational pattern. 6.4 Operational pattern qualifiers This operational pattern shall support the qualifiers as specified in byte 15 of the operational pattern universal label. Each bit of byte 15 shall be correctly set, as defined by SMP
39、TE 377M, to reflect the status of the essence container. 6.4.1 Essence container location The essence containers should be embedded in the file body for interchange applications. The essence containers may be externally referenced for certain specialized applications. Example applications might incl
40、ude shared-storage networks, archives and other applications where the access to an essence container is localized and the locator value (defined by a locator set in SMPTE 377M) is persistent. If all the essence containers are internal to the file, then bit 1 shall be set to zero. Guidance on extern
41、al essence is given in SMPTE EG 41. 6.4.2 Interleaving of multiple essence tracks Essence containers used in this operational pattern should be streamable. If all the essence containers are streamable, and have been multiplexed in a way that makes the overall file streamable, then bit 2 shall be set
42、 to zero. If the primary package references any external essence then the file shall not be made streamable. Guidance on streamability is given in SMPTE EG 41. 6.4.3 Number of essence tracks This operational pattern supports multiple essence containers, each with one or more essence tracks. If all t
43、he essence containers have a single essence track, then bit 3 shall be set to zero. 6.4.4 Qualifiers specific to this operational pattern Each bit of byte 16 shall be correctly set, as defined in table 3 and in the subsections which follow. SMPTE 393M-2004 Page 7 of 9 pages Table 3 Byte 16 of the op
44、erational pattern label Bit number Values and Descriptions 0-3 Reserved for future use, encoder should set to zero 4 =0 no inter-SourceClip processing needed At the join of 2 Material Package SourceClips, no special processing is required. An essence decoder will be able to decode the stream which r
45、esults from the data from the first SourceClip butted onto the second SourceClip. =1 no knowledge of the inter-SourceClip processing is available No assumptions can be made about the processing required to butt edit the essence streams. A long GoP MPEG stream may require extra frames to pre-charge t
46、he decoder. Other essence types may require other processing. 5-7 Reserved for future use, encoder should set to zero 6.5 Minimum implementation recommendation All constraints given in the MXF file format specification shall apply unless specifically overridden or extended in this document. The mini
47、mum implementation of operational pattern 2b is recommended to have the following limits in reference to the MXF file format specification. This section is a recommendation because the exact structure of the sets depends on how many of the top-level file packages reference external data. 1 preface s
48、et, 1 or more identification sets and 1 content storage set and 4 or more essence container data sets. One material package including: the sets for the time code track; the sets for each picture track as required by the essence container; the sets for each sound track as required by the essence cont
49、ainer; the sets for each data track as required by the essence container. Four or more top-level file packages each including: the sets for each picture track as required by the essence container; the sets for each sound track as required by the essence container; the sets for each data track as required by the essence container. NOTE Support for descriptive metadata is optional but at least one scheme should be included in order to get the best from an MXF file. The annexes of the MXF format specification give the properties of the
