Unit 5: Multimedia Representation and Storage

Unit 5: Multimedia Representation and Storage

Data Compression http://en.wikipedia.org/wiki/Data_compression

Data Compression: Encoding information using fewer bits, through specific coding schemes.

Compression is only successful if both the sender and receiver of the information understand the encoding scheme.

Compression helps reduce the consumption of hard disk space, transmission bandwidth, etc.

- but has to be decompressed then to use, adds another step

Lossless and Lossy compression:

-Lossless: algorithms help remove redundancy without error

-Lossy: rounding off of some less important information (some info is lost that the reader/viewer would not necessarily notice)

This wiki is very helpful in understanding the benefits and downfalls of compressing information. It would probably be a bad idea to compress a large video for a presentation, because the chances of being able to watch it while it is decompressing are slim. But libraries could benefit from compressing metadata, shrinking the space of their digital catalog and making more information available.

Data Compression Basics http://dvd-hq.info/data_compression_1.php

This website is a great index of the ins and outs of data compression. The step by step information regarding DVD Video compression is a great tool for future reference.

Some of the examples of data compression encoding are interesting as well.

-Run-Length Encoding: replaces sequences of identical characters with a single character. Lossless

ex. AAABBBBCCCCCDDDDDD

- 3A 4B 5C 6D

-Prediction coding seemed useful, but it also doesn't seem very functional for somethings, like telephone numbers, or call numbers. A list of call numbers would not work for this type of compression.

Some of the other types of encoding go way over my head, but I can see how they are effective.

Interesting note: I tried repeatedly (and in several different types of browsers, Safari, Firefox, and Google) to access the lossy compression page and got this message: The page you are trying to view cannot be shown because it uses an invalid or unsupported form of compression.

Ironic?

Also, the list of references for this article are almost all wikipedia sites. Essentially this article creates a one stop shop for data compression that you would have to click through several links to get it all in wikipedia.

Edward A. Galloway, "Imagining Pittsburgh: Creating a shared gateway to digital image collections for the Pittsburgh region" http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/view/1141/1061

The Digital Research Library at Pitt, headed by Galloway, oversaw a huge photograph digitization project to create a website for individuals to access photographs from Western PAs past.

-access through the Historic Pittsburgh website

-collection collects over 20 distinct collections

-Characteristics of the Web 'Gateway:'

-Keyword search

-Browse within any collection

-Read about the collections and their content (provenance, dates, coverage)

-Explore the images by time, place and theme

-Order image reproductions

Challenges:

-communication: actual communication issues, meetings, email listservs…, but also communication across different institutes goals and missions.

-selection: deciding what images would be scanned and digitized

metadata: standardizing metadata schemas across the project (ended up using LCSH)

-workflow: keeping the images flowing through selection, digitization, description, and quality control

-making sure the metadata from different institutions would export to the DRL's format

-Website development

*This was a very interesting article for me to read in particular. My Pitt Partners placement is with the Oakmont Carnegie library and I am working on digitizing the library's collection of historical photographs. One of the most important training aspects of the project was learning how to categorize and specify the metadata. Some of the issues Galloway discusses in this article are issues I experience on a regular basis.

Paula L. Webb "Youtube and Libraries: It could be a beautiful relationship"

http://www.ala.org/ala/mgrps/divs/acrl/publications/crlnews/2007/jun/youtube.cfm

Webb argues that Youtube is a great tool for librarians to post videos about what services they offer, instructional videos, and videos on where to gain more information. It could also serve as a 'storehouse' for library information readily available for anybody to access.

ex. a college library's freshman orientation video could get posted for easy access

I think it is a great idea. Let people know what is available in a really familiar format and you will greatly increase your patron base.