Latest Status of UMID and Its Applications in File-based Workflow
27 Latest Status of
by Yoshiaki Shibata Chair, SMPTE TC-30MR SG UMID Applications
Introduction
The UMID (Unique Material IDentifier) is a globally unique AV (audiovisual) material identifier standardized by SMPTE (Society of Motion Picture and Television Engineers) as SMPTE ST 330 and RP 205. More than a decade has passed since its initial standardization in 2000 and its presence in AV products using the MXF (Material Exchange Format), files containing the UMID as its mandatory component have been widely spread throughout the industry. But, its originally intended use as a unique material identifier to link AV material to its metadata has seldom been seen in practice.
In addition, although AV material management using a unique identifier is a common practice observed in variety of products, a problem with the material identifier often occurs when such products are combined to form a media production system. The UMID, as an industry common AV material identifier, is expected to address this sort of problem. In reality, however, most products have their own proprietary material identification schemes with little or no interoperability between them. Furthermore, although certain products have adopted the UMID for their material identifier, they have no capability to communicate with other products via the UMID, resulting in failure of their integration into a system.
Recently, we have revealed that the issue is mainly due to lack of industry common rules for the UMID applications and, in order to address the UMID application issue, a new project has just begun in the SMPTE SC (Standard Community).
In this article, the goal of UMID and its applications are discussed, together with the needs of industry common UMID application rules to achieve it, followed by possible UMID applications specifically for MXF. Then the UMID application project recently approved by the SMPTE SC is introduced to call for your participation.
Goal of UMID Applications
Figure 1 shows the structure of UMID format. The UMID is inherently a single 32-byte entity that takes the form of well-known KLV (Key-Length-Value) structure. The first 12-byte Key field, called the SMPTE UL (Universal Label),
indicates that this is the UMID. The 1-byte Length field specifies the length of byte string that follows, which is fixed to 13h. The Value field is divided into two components: the 3-byte Instance Number (Inst.#) to signal its originality that is usually set to zero, and the 16-byte Material Number (Mat.#) to accommodate a globally unique value that makes the UMID as a globally unique identifier.
UMID and its Applications in File-based Workflow
Figure 1: UMID Format
The primary use of UMID is as a globally unique AV material identifier. Because the UMID is usually attached to the AV material that needs to be globally uniquely identified with a UMID, metadata can be unambiguously associated with the AV material by specifying the reference to it via the UMID. This leads to a typical UMID application called the UMID based AV material search (Figure 2).
Figure 2: UMID based AV Material Search
In Figure 2, AV materials are stored in various kinds of material servers and a section of descriptive metadata associated with an AV material via its UMID are collected and separately stored altogether in a Metadata database. When an application (App.), such as video editing, wants to obtain an AV material that captures the “Ichiro Homerun” scene for example, it gives the request to the Metadata database accordingly. The Metadata database then replies to the application the requested AV material via its UMID.
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