Variable Bit Rate (VBR)
Variable Bit Rate (VBR) – Operation where the bit rate changes with time during the decoding of a compressed bit stream. Although variable bit rate is acceptable for plain linear playback, one important consideration for not using VBR is that quick random access becomes nearly impossible. There is no table of contents or index in MPEG. The only tool the playback system has for approximating the correct byte position is the requested playback time stamp and the bit rate of the MPEG stream. MPEG streams do not encode their playback time. To approximate an intermediate position in a variable bit rate stream, the playback system must search data near the end of the stream to calculate the playback time, and assume the stream has an approximately constant bit rate. The search for the correct position can take several seconds. This searching is at least annoying when trying to view a portion of a movie but it is not even possible for video streams because there are no time stamps (the SMPTE time codes in video streams need not to be continuous or unique). Audio streams are always fixed bit rate.
Source: http://download.tek.com/secure/25W_15215_1.pdf?nvb=20151220132843&nva=20151220133343&token=0538ce9690041d6978723
Web site to visit: http://www.tek.com/
Author of the text: http://www.tek.com/
If you are the author of the text above and you not agree to share your knowledge for teaching, research, scholarship (for fair use as indicated in the United States copyrigh low) please send us an e-mail and we will remove your text quickly. Fair use is a limitation and exception to the exclusive right granted by copyright law to the author of a creative work. In United States copyright law, fair use is a doctrine that permits limited use of copyrighted material without acquiring permission from the rights holders. Examples of fair use include commentary, search engines, criticism, news reporting, research, teaching, library archiving and scholarship. It provides for the legal, unlicensed citation or incorporation of copyrighted material in another author's work under a four-factor balancing test. (source: http://en.wikipedia.org/wiki/Fair_use)
The information of medicine and health contained in the site are of a general nature and purpose which is purely informative and for this reason may not replace in any case, the council of a doctor or a qualified entity legally to the profession.
The following texts are the property of their respective authors and we thank them for giving us the opportunity to share for free to students, teachers and users of the Web their texts will used only for illustrative educational and scientific purposes only.
All the information in our site are given for nonprofit educational purposes
The information of medicine and health contained in the site are of a general nature and purpose which is purely informative and for this reason may not replace in any case, the council of a doctor or a qualified entity legally to the profession.
www.riassuntini.com