SMPTE336M标准MXFKLV资源-CSDN文库

需积分: 10 118 浏览量 2012-04-17 17:51:09 上传评论收藏 104KB PDF 举报

### SMPTE 336M标准与MXF KLV数据编码协议详解 #### 一、概述 SMPTE 336M标准是一项由Society of Motion Picture and Television Engineers（电影与电视工程师协会，简称SMPTE）制定的重要规范，主要用于定义一种八位字节级别的数据编码协议，即MXF（Material Exchange Format）文件中的KLV（Key-Length-Value）数据交换格式。此标准旨在为电视视频内容的数据交换提供一个统一且灵活的框架。 #### 二、标准范围与目标 SMPTE 336M标准的核心是定义了一个能够表示数据项和数据组的八位字节级别数据编码协议。该协议所定义的数据结构独立于具体的应用场景或传输方式，这意味着无论是在何种环境中，只要遵循这一标准，都能够实现数据的有效交换。 #### 三、KLV协议详解 **1. Key-Length-Value (KLV) 数据结构** KLV协议是通过三个组成部分来构建数据交换的基本单位：键(Key)、长度(Length)和值(Value)。其中， - **键(Key)**：用于唯一标识数据项； - **长度(Length)**：指明值(Value)部分的长度； - **值(Value)**：则是实际要交换的数据内容本身。这种结构提供了所有符合该标准的应用程序之间通用的数据交换格式，无论这些应用程序的具体实现方法如何。 **2. 数据集的组合** 除了单个KLV数据项之外，SMPTE 336M还支持将相关的KLV数据项组合成数据集。这些数据集可以采用不同的形式进行编码： - **全形式（Universal Sets）**：提供最完整的信息，便于理解。 - **全局集（Global Sets）**：相对于全形式更为紧凑，适用于特定类型的组合。 - **局部集（Local Sets）**：进一步减少数据量，适用于更具体的场景。 - **可变长度包（Variable-Length Packs）**：根据数据的实际长度动态调整编码方式，提高效率。 - **固定长度包（Fixed-Length Packs）**：在预知数据长度的情况下，采用固定长度进行编码，简化处理流程。 #### 四、编码范围与限制由于SMPTE 336M标准允许较大的数据编码范围，因此在实际应用时可能会产生大量数据。为了应对这种情况，具体的应用文档通常会规定KLV编码的适用范围以及相关的细节，以确保数据的有效管理和传输。 #### 五、规范性引用文件 SMPTE 336M标准的实施依赖于其他规范的支持，主要包括： - **ANSI/SMPTE 298M-1997**：《电视——数字数据唯一标识通用标签》。该标准定义了数字数据的唯一标识符，有助于确保数据的唯一性和可追踪性。 - **ISO/IEC 8825-1:1998 (ITU-T X.690)**：《信息技术——ASN.1编码规则——基本编码规则(BER)、规范编码规则(CER)和区别编码规则(DER)的说明》。这是关于数据编码的重要国际标准，为数据的结构化编码提供了基础。 #### 六、总结 SMPTE 336M标准通过定义MXF文件中的KLV数据交换格式，为电视视频内容的数据交换提供了一个强大而灵活的框架。该标准不仅确保了不同应用场景之间的数据兼容性，还支持多种数据集的组合方式，极大地提高了数据交换的效率和灵活性。对于从事电视视频制作和传输的专业人士而言，理解和掌握SMPTE 336M标准是非常重要的。

资源推荐

资源详情

资源评论

1 Scope

This standard defines an octet-level data encoding

protocol for representing data items and data groups.

This protocol defines a data structure which is inde-

pendent of the application or transportation method

used.

The standard defines a key-length-value (KLV) triplet

as a data interchange protocol for data items where

the key identifies the data, the length specifies the

length of the data, and the value is the data itself. The

KLV protocol provides a common interchange for all

compliant applications irrespective of the method of

implementation or transport.

The standard also provides methods for combining

associated KLV triplets in data sets where the set of

KLV triplets is itself coded with KLV data coding pro-

tocol. Such sets can be coded in either full form

(universal sets) or in one of four increasingly bit-effi-

cient forms (global sets, local sets, variable-length

packs, and fixed-length packs). The standard pro-

vides a definition of each of these data constructs.

The encoding octet range (length of the payload)

specified in this standard may generate unusually

large volumes of data. Consequently, a specific appli-

cation of KLV encoding is capable of only a limited

operating data range and those details shall be de-

fined in a relevant application document.

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

standard are encouraged to investigate the possibility

of applying the most recent edition of the standards

indicated below.

ANSI/SMPTE 298M-1997, Television — Universal

Labels for Unique Identification of Digital Data

ISO/IEC 8825-1:1998 (ITU-T X.690), Information

Technology — ASN.1 Encoding Rules — Specification

of Basic Encoding Rules (BER), Canonical Encoding

Rules (CER), and Distinguished Encoding Rules

(DER)

3 Key-length-value (KLV) protocol

Table 1 and figure 1 present an introductory view of

the key-length-value (KLV) protocol for encoding data.

The data encoded may be a single data item or a data

group. The coding of data items is described in clause

4 while the coding of data groups is described in

clause 5 of this standard.

The KLV coding protocol is composed of a universal

label (UL) identification key (UL key), followed by a

numeric length (value length), followed by the data

value.

The composition of the UL key is described in 3.1

of this standard. The length of the full UL key shall

be 16 octets. The length field is described in 3.2 of

this standard. The value is described in 3.3 of this

standard. The value is a sequence of octets of the

data type as specified in a relevant standard and is

not further specified by the KLV protocol. The length

of the value field is variable and any limitations are

defined in a relevant defining standard.

Approved

March 28, 2001

MOTION PICTURE AND TELEVISION ENGINEERS

595 W. Hartsdale Ave., White Plains, NY 10607

(914) 761-1100

for Television —

Data Encoding Protocol

using Key-Length-Value

SMPTE 336M-2001

SMPTE STANDARD

Page 1 of 25 pages

The bit-order (lsb or msb first) for KLV encoding

shall be that of the transport used to carry the

information.

3.1 ANSI/SMPTE 298M universal label key

KLV coding protocol shall use a 16-word universal

label (UL) according to SMPTE 298M as the UL key

to identify the data in the value field.

Each word in the SMPTE 298M UL is coded using the

basic encoding rules (BER) for the encoding of an

object identifier value specified in ISO/IEC 8825-1, para-

graph 8.19. Each word of the UL key shall be limited to

the range 0×00 to 0×7F and shall be represented by a

single octet. The UL key shall have left-to-right signifi-

cance with the first octet as the most significant. The

leftmost octet of value 0×00 in the UL key shall define

the termination of the label and all octets of lower

significance shall also be set to 0×00. Octets of value

0×00 shall have no significance to the meaning of the

UL key.

The full UL key consists of a 16-octet field including

an object ID (OID) and the UL size (0×0E indicating a

total UL key size of 16 octets) followed by a UL code

and a series of subidentifiers which shall define the

UL designators. The first two UL designators shall

have reserved values for the KLV coding protocol

according to this standard.

NOTE – The SMPTE UL itself adopts KLV coding with

the object ID as the key, the UL size as the length, and

the UL designators as the value.

When applying the SMPTE UL to the coding of data

according to this standard, these fields shall be cate-

gorized as the UL header, UL designators, and item

designator as shown in table 2.

Field Description Length Content/Format

UL key Universal label for identification

of the value

16 octets Clause 3.1

Length Length of the value field Defined in a relevant dictionary, essence,

application standard, but variable length

Clause 3.2

Value Value associated with the UL key Variable

Clause 3.3

Table 1 – Key-length-value (KLV) fields for encoding of data

ValueUL Key Length

16 octets BER

Variable Length Octets

Length

Figure 1 – Key-length-value (KLV) encoding

SMPTE 336M-2001

Page 2 of 25 pages

Annex C shows an informative example of a metadata

UL key from the SMPTE metadata dictionary in tabu-

lar and figure formats.

Note that decoders which recognize the UL key but

do not want to, or cannot, decode the associated value

may ignore the item and shall continue the decoding

process of subsequent items using the length value

to skip the value of the undecoded item. If decoders

only store or forward the item, they shall forward the

item unaltered.

3.1.1 UL designators

Table 3 defines octet values for the designators to be

used in octets 5 through 7 of the UL designators.

SMPTE standards and recommended practices

which define a UL key with the value of octet 5 (registry

category designator) in the range 0×01 to 0×04 shall

Registration Authority in the registry identified by

octets 6 and 7 (registry designator and structure

designator).

3.1.1.1 Dictionaries

SMPTE standards and recommended practices

which define the value of word 5 of the UL key as 0×01

are dictionary standards and shall be used to define

single data items with the KLV data construct.

The coding of individual items is defined in clause 4.

3.1.1.2 Sets and packs

SMPTE standards and recommended practices

which define the value of word 5 of the UL key as 0×02

are set and pack standards and shall be used to define

groups of KLV coded data items.

The coding of data groups is defined in clause 5.

3.1.1.3 Wrappers and containers

SMPTE standards and recommended practices

which define the value of word 5 of the UL key as 0×03

are wrapper and container standards and use the UL

key to identify the wrapper or container and its con-

tents. Wrappers and containers differ from sets and

packs in that they do not necessarily employ an

overall KLV data construct for the entire contents of

the wrapper or container. It is recommended that

individual parts of a wrapper or container encode data

using the KLV coding protocol, but these parts may be

bound together by other techniques. In some cases,

a wrapper or container may employ an overall KLV

No. Field Description Length Content/Format

UL header:

1 OID Object identifier 1 octet

Always 0×06

2 UL size 16-octet size of the UL 1 octet

Always 0×0E

UL designators:

3 UL code Concatenated subidentifiers ISO, ORG 1 octet

Always 0×2B

4 SMPTE designator SMPTE subidentifier 1 octet

Always 0×34

Registry category

designator

Registry category designator identifying

the category of registry described (e.g.,

dictionaries)

1 octet See table 3

6 Registry designator Registry designator identifying the specific

registry in a category (e.g., metadata

dictionary)

1 octet See table 3

7 Structure designator

Designator of the structure variant within

the given registry

1 octet Clause 3.1.2

8 Version number

Version of the given registry which first

defines the item specified by the item

designator

1 octet Incrementing number

9-16

Item designator Unique identification of the particular item

within the context of the UL designator

8 octets See relevant standard

and version

Table 2 – Field descriptions for the universal label key for the KLV encoding of data

SMPTE 336M-2001

Page 3 of 25 pages

construct in certain applications (such as a streaming

interface) but employ another technique in other appli-

cations (such as a storage container). In these cases,

the wrapper or container is not redefined as a set or

a pack but retains the definition as a container or

wrapper for consistency of identification.

Simple wrappers and containers are defined as em-

bedding all the data into a single framework with no

external references.

Complex containers and wrappers are defined by

frameworks where individual data items may be in-

cluded in a file by reference rather than embedding.

Complex containers and wrappers can be more effi-

cient and are suited to local environments where

references can be easily resolved.

The definition of wrappers and containers is outside

the scope of this standard and can be found in other

documents.

3.1.2 Structure designator

Octet 7 shall contain the structure designator for the

given registry.

Structure designators are allocated to distinguish be-

tween incompatible versions of the same registry.

They may be thought of as a major version number.

NOTE – Different structure designators may be assigned

when a registry becomes so cluttered that it has outlived its

usefulness, or when changes to the contents, structure, or

class relationships of the registry are necessary which

prevent backward compatibility.

Different structure designators may also be assigned to

distinguish between different syntax rules for construction

and interpretation of values.

Different structure designators may also be assigned when

more than one standard or practice is used to define the

contents of a specific registry.

Registry

category Registry Structure

Octet 5 Octet 6 Octet 7 Described in

01 – Dictionaries Clause 4

01 – Metadata dictionaries

0×01-0×7F– Structure designator

Other standard/practice

02 – Essence dictionaries