What exists beyond the world of MARC: Metadata Standards Review 1 - PBCore and media asset management By Tom Adamich Metadata standards have become an important topic of discussion in libraries of all types in recent years. As the number and complexity of resources to be accessed in libraries of all types multiplies exponentially, so does the need to provide access to these materials (not only in the virtual PC environment but in the mobile segment of the virtual world as well). Each format developed (particularly those that are multimedia-based) have associated metadata-based documentation requirements that accompany them. It is these multimedia-based products that are becoming a large part of library collections. In multimedia creation and broadcasting circles, the phrase “media assets management” has become a buzzword to describe the overall management of these resources for use in the Internet-based virtual library environment. According to Andries in “Media Data Centre – The Path to Performance and Efficiency in the Media Workflow, media asset management involves a variety of Internet and file-based media production and delivery protocols which include the following: IP network-based access and transport of the media; � central disk-based media storage; � server-based (non-linear) video editing or processing; � software-based media management and media production systems. Together with the appearance of some product formatting standards like MXF (Material eXchange Format) and AAF (Altered Auditory Feedback), which provide a generic file container for the media essence (and associated metadata), these changes have led to the file-based paradigm of media essence (Andries, 2010, 1) The next step is to take the media essence (which may be found in a number of forms, including but not limited to high-resolution video - for broadcasting via satellite or online, low-resolution proxy video and audio - for website-based streaming media or other Internet-based applications) and house it in a media assets management system (which will enable the media essence to be transcoded and archived as well) (Andries, 2010, 3). In this installment of “Making and Managing Metadata” we’ll examine the first of several metadata standards which have been developed over the last few years as a result of the need to store and document motion media in ways that are markedly different from tradition library materials. One of those metadata standards is the PBCore metadata standard. What is PBCore, and how can it benefit libraries? The PBCore metadata standard, based on the Dublin Core Metadata Standard (ISO 15836), is used to describe media (video, audio, text, images, rich interactive learning objects). According to Pinch in Tools for Collaboration: PBCore and More, PBCore was created by the Public Broadcasting community in the United States in 2005 with 48 elements. (Pinch, 2011, 4) Version 2.0 was released in February, 2011 and now contains 80 elements. PBCore enables both Public Broadcasters and related communities to easily retrieve and share media assets among colleagues, various software systems, institutions, community/ production partners, private citizens, and educators. PBCore can also be used as a foundation for an archival or asset management process at an individual PBS station or institution. Another advantage in using PBCore, according to Pinch, is the ability to amortize the cost of gathering metadata information from multiple sources in the media production process (producers, directors, technicians, etc.) by using one common platform that all stakeholders use to contribute, manage, and share metadata. Thus, each party can contribute/manage/share metadata instantaneously at their participation point in the media process rather than having the content interpreted following production (which is the traditional media cataloging method used in the past – often identified as “end-of-product cataloging”). Libraries may have the opportunity to examine traditional end-of-product cataloging workflow to determine what advantages may be realized when metadata which accompanies media received by the institution is extracted and sampled for quality control purposes to determine if automated metadata generation processes are functioning properly. Again, awareness that a metadata standard such as PBCore has been used (or its derivatives such as Dublin Core or the European Broadcasting Union Core – EBUCore – a standard to be profiled in a future Making and Managing Metadata column) would promote metadata generation efficiency across the metadata creation process (as well as make metadata readily available for access and modification, if needed). Ultimately, the goal of the PBCore standard is to provide a pivotal identification point for the achievement of the real power of digital technology to meet the mission of public broadcasting – access to quality media for all U.S citizens. For libraries, providing access to quality media being generated on behalf of the communities they serve http://www.pbcore.org Who created PBCore, and what does it look like? As mentioned earlier, PBCore was created in 2005 by a metadata working group consisting of 30 representatives of local and national television and radio organizations. The group’s advisors included the University of Washington Information School, the Department of Defense’s Academic CoLab, and the Rutgers University/The Association of Moving Image Archivists. Other PBS stakeholders were also involved in many of the preliminary discussions Additionally, executives from the PBS flagship station WGBH administered the project. (Brooks, 2009) The following is an example of PBCore metadata record creation rationale as it relates to media being described: PBS Tapes Here is a generic example of how a single PBS program, identified as “ABCD 101,” might be represented by multiple master and backup reels (MR1, MR2, etc.) in the PBS library system. In our PBS Archives PBCore sample records, I have chosen to document the “Version 1” and “Version 2”-level information only. Add the expanded layer of the upcoming PBS containerization effort, and the underlying media/file list for every program could increase exponentially. This may have serious implications for future extensions to the PBCore element set. Other applications which may exist include displaying PBCore using the XML Stylesheet Language (XSLT) to produce web pages and combining PBCore+XSLT+CSS into an HTML stylesheet According to PBS Executive Glen Chatworthy: It can be hard for laymen to visualize the concept of “metadata” and PBCore. I realized early on that I needed to find a way to display our PBCore records as web pages so that I could display the results in a meaningful way for casual viewers. In the course of producing my automation system, I learned just enough about XML Stylesheet Language Transformations (XSLT) and Cascading Style Sheets (CSS) to produce XML files that would display as web pages in contemporary browsers. Sample runs include appropriate links in the PBCore XML files as well as XSLT and CSS stylesheets in related directories.” (Chatworthy, 2009) Below is an example of PBCore metadata standard output in a traditional library catalog environment: Home Page http://www.mnvideovault.org/index.php PBCore as a media asset metadata standard for libraries Ultimately, the goal of PBCore will continue to be to provide documentation standards and protocols for the Public Broadcasting community. However, the structure of PBCore itself (and its Dublin Core origins) has the potential to enable the standard to be easily adapted and utilized by libraries and other organizations faced with managing multimedia resources in an Internet-based media assets management environment. PBCore also has the potential to encourage libraries to examine their traditional end-ofproduct cataloging processes (with respect to media productions as well as other materials) to determine if the metadata ingest and workflow processes associated with Public Broadcasting media asset metadata creation and management (using PBCore or a similar metadata standard) have the potential of being utilized/modified by the library community to promote efficiency, save dollars, provide quick access to quality media resources, and act as an element of efficient and effective media asset archiving and governance. References: Andries, Luc. 2010. Media Data Centre – the path to performance and efficiency in the media workflow. In “EBU Technical Review”, 2010 Q4, 2. Brooks, Marcia. 2009. Electronic mail correspondence, July 30, 2009; Accessed May 21, 2011. Chatworthy, Glen. 2009. Electronic mail correspondence, July 15, 2009; Accessed May 21, 2011. Jacobs, Bruce. 2009. Electronic mail correspondence, July 30, 2009; Accessed May 21, 2011. Pinch, Peter. Tools for Collaboration: PBCore and More. Presented at the 2011 Integrated Media Association Conference (Austin, TX : March 10-15, 2011). Available at: http://pbcore.org/news/pbcore-presentation-at-ima-2011/ . Accessed May 31, 2011. Additional Resource: Motion Media Glossary Source of terms (used with permission) Dan Rayburn StreamingMedia.com http://www.streamingmedia.com/glossary Animation A series of still images displayed quickly to simulate motion. Some key examples of Web animation include Shockwave, Flash, and animated GIFs. ASF Most streaming media files encoded for use on the Windows Media platform have a .asf extension. This is an actual audio/video file, as opposed to an ASX file. ASX A metafile which points to a Windows Media audio/video presentation. AVI (Audio/ Video Interleaved) - A Microsoft-specified format for saving audio and/or video clips, referred to by Windows as "Video for Windows." You can play the files through the Media Player in Windows or through many popular browser plug-in multimedia players. Bit rate The speed at which data travels from one place to another on a computer network, such as the Internet. Capture Process of digitizing audio and video content from an analog format. Digital Video Digital video is the key to content when streaming media. Digital video is an alternative way of storing or distributing video. Digital video is usually converted from an analog video source. A digital video signal is represented in '1's and '0's, whereas an analog video signal is represented by a fluctuating voltage signal that is stored on magnetic tape. This difference is similar to the difference between analog audio and digital audio. Digitizing Process of capturing or "bringing in" audio and/or video (usually analog source tapes such as Beta SP, 3/4, VHS, etc.) into a computer. Digitizing is made possible by video hardware, a computer hardware card, cables, and a software application that all work together to convert the original signal into digital media. This digital media can then be edited and transferred back to numerous formats for Internet streaming, CD-Rom, DVD, and other forms of distribution. Submitted by: Brian Tane Frame Rate The number of frames of video displayed during a given time -- usually measured in seconds. Standard television video is almost 30 Frames Per Second (fps). Flash Vector-based animation format released by Macromedia often used for narrative productions on the web. Interframe method Interframe method is a type of video compression used by MPEG which compresses three types of frames: I-Frames, P-Frames and B-Frames.In I-Frames, the entire scene is compressed. PFrames are compressed with reference to a Past-I or P-Frame. B-Frames provide the highest amount of compression but require both a past and a future frame as a reference. The image sequence in MPEG is flexible, depending on application specific parameters. Interstitial Any web-based advertisement which occurs before, after, or during a narrative content presentation. For example, if streaming media terminology were applied to regular television, standard television commercials would be called interstitials, since they interrupt programming ISDN (Integrated Services Digital Network). A set of standards for transmitting digital information over ordinary telephone copper phone lines and other media. With an ISDN adapter (both at your computer and at your Internet service provider), you can send and receive transmissions much faster than using a conventional modem. M3U A metafile which points to an MP3 stream. MP3 MP3 is the MPEG audio layer 3 standard. Layer 3 is one of three coding schemes (layer 1, layer 2 and layer 3) for the compression of audio signals defined by the MPEG committee. Layer 3 uses perceptual audio coding and psychoacoustic compression to remove the redundant parts of a sound signal. It also adds a MDCT (Modified Discrete Cosine Transform) that implements a filter bank, increasing the frequency resolution 18 times higher than that of MPEG audio layer 2. MPEG MPEG is a digital video and audio compression format that was defined by the Moving Pictures Experts Groups which is part of the International Standards Organization (ISO). MPEG is a lossy compression method which uses Interframe compression. Interframe compression assumes that although action is happening, the background in most video frames remains the same. This means that it is not necessary to compress each entire frame, but only the differences between them. The Interframe method compresses three types of frames: I-Frames, P-Frames and BFrames MPEG-4 MPEG-4 defines how multimedia streams – video, audio, text, data – are transmitted as individual objects. MPEG-4 is a compression/decompression technology that aims to achieve interactivity, efficiency and stability in narrow-band transmissions. On a broader level, MPEG-4 aims to pave the way toward a uniform, high quality encoding and decoding standard, that would replace the many proprietary streaming technologies in use on the Internet today. MPEG-4 is also designed for low bit-rate communications devices, such as mobile receivers or wristwatches that can display video. These devices are usually wireless and can have different access speeds depending on the type of connection and traffic. To overcome this problem, MPEG-4 supports scalable content. Content is encoded once and automatically played back and transmitted at different rates, depending on the available network connection. Multicast A process which allows a server to send one stream to multiple recipients. This is different from traditional streaming media, where each user connects separately to a server. Narrowcast To send data to a specific list of recipients. On the Internet, narrowcasting has also come to refer to programming developed for "niche" interest groups. Packet A chunk of data organized in a block for transmission over an IP network. Usually contains header information with origin and source address, and employs error-correction. Pointer files Text files that point to the actual location (server and filename) of a streaming file. Almost all systems use pointer files. Progressive Download A method of delivering audio/video data over the Internet that involves playing the downloaded portion of a file while the download is still in progress. Also referred to as "Pseudo-Streaming". protocol A uniform set of rules that enable computers to connect to one another. Protocols determine how data is transmitted between computing devices and over networks. As such they define issues such as error control and data compression methods. QuickTime Multimedia architecture used by software tool vendors and content creators to store, edit and play synchronized graphics, sound, video, and music. RAM A metafile which points to a RealMedia file. RealMedia Brand name describing file formats, server software, player software, and protocols used by streaming media systems from RealNetworks, a leading streaming media platform vendor. RealAudio©, RealVideo©, and RealFlash© are examples. Rich Media Media that has been enhanced with animation or video. Rich media ads are animated, and often streamed, so that they appear more like television commercials, as opposed to ads containing static images and text. They can be embedded in Web pages and inserted into or between video clips. Using SMIL, they can be streamed concurrent to audio programming. RTP (Real Time Protocol) – An Internet protocol that defines the transmission of real-time data, such as audio and video. RTP provides mechanisms for the sending (server) and receiving (client) applications to support streaming data. RTSP Real-Time Streaming Protocol: a standard method of transferring audio and video and other time-based media over Internet-technology based networks. A descendent of UDP. Simulated live Describes a completed audio/video program which is presented on the web as though it were live. Audience members must tune in to the program. If the scheduled start time has already passed, audience members will join the program in progress (also referred to as video on demand – VOD). SMIL Synchronized Multimedia Integration Language. A text-based mark-up language used to synchronize disparate media elements (such as text, animations, audio and video) within one streaming media presentation. streaming media Streaming media technology enables the real time or on demand distribution of audio, video and multimedia on the internet. Streaming media is the simultaneous transfer of digital media (video, voice and data) so that it is received as a continuous real-time stream. Streamed data is transmitted by a server application and received and displayed in real-time by client applications. These applications can start displaying video or playing back audio as soon as enough data has been received and stored in the receiving station’s buffer. A streamed file is simultaneously downloaded and viewed, but leaves behind no physical file on the viewer's machine. UDP User Datagram Protocol. A method of communicating between computers which does not guarantee that ever bit arrives at its end destination. Favored for time-sensitive data such as streaming media. Unicast A process which forces each individual user to make an individual connection to a server to receive a stream (as opposed to Multicast, which allows multiple, simultaneous access to a stream). Video Compression The process through which a complete video file is reduced in size. Video Compression algorithms take advantage of the fact that there is minimal difference from "one" frame to the next. The first frame is encoded and then the sequence of differences between frames. This is also known as "inter-frame" coding or "3D coding" Video On Demand Describes video content which may be viewed by the end-user from beginning to end, at any time. WAV (Wave Form Audio) - Files with the .wav extension are digital representations of sound and typically take up a good deal of space to store (typically 50MB for a 5 minute song, for instance). If you use software to rip files from an audio CD, it is usually stored in .wav format. Standard Windows sounds are also stored in .wav format. Webcasting A live broadcast format over the World Wide Web (WWW).