Variable bitrate is a term used in telecommunications and computing that relates to the bitrate used in sound or video encoding. As opposed to constant bitrate, VBR files vary the amount of output data per time segment. VBR allows a higher bitrate to be allocated to the more complex segments of media files while less space is allocated to less complex segments; the average of these rates can be calculated to produce an average bitrate for the file. MP3, WMA and AAC audio files can optionally be encoded in VBR, while Opus and Vorbis are encoded in VBR by default. Variable bit rate encoding is commonly used on MPEG-2 video, MPEG-4 Part 2 video, MPEG-4 Part 10/H.264 video, Theora and other video compression formats. Additionally, variable rate encoding is inherent in lossless compression schemes such as FLAC and Apple Lossless; the advantages of VBR are that it produces a better quality-to-space ratio compared to a CBR file of the same data. The bits available are used more flexibly to encode the sound or video data more with fewer bits used in less demanding passages and more bits used in difficult-to-encode passages.
The disadvantages are that it may take more time to encode, as the process is more complex, that some hardware might not be compatible with VBR files. VBR may pose problems during streaming when the instantaneous bitrate exceeds the data rate of the communications path; these problems can be avoided by limiting the instantaneous bitrate during encoding or by enlarging the playout buffer. In the past, many hardware and software players could not decode variable bitrate files properly because the various VBR encoders used were not well developed; this resulted in common use of CBR over VBR for the sake of compatibility. As of December 2006, devices that support only CBR encoded files are obsolete, as the vast majority of modern portable music devices and software support VBR encoded files. Support for VBR in AAC and MP3 files is found in most modern digital audio players, including those released by Apple, Creative Technology, SanDisk. Early VBR algorithms introduced audible artifacts when encoding monotone or minimal tones.
These artifacts mimicked a "digital chirp" during the quiet portions of the song or when there was only speaking. As VBR encoding algorithms have improved, these problems have been resolved in subsequent generations of the VBR standard. Note that the choice of a variable bitrate method only affects the encoding process. Decoding a VBR stream is performed identically in all cases, regardless of how the encoder chooses to allocate bits. VBR is created using multi-pass encoding. Single-pass encoding analyzes and encodes the data "on the fly" and it is used in constant bitrate encoding. Single-pass encoding is used when the encoding speed is most important — e.g. for real-time encoding. Single-pass VBR encoding is controlled by the fixed quality setting or by the bitrate range or by the average bitrate setting. Multi-pass encoding is used. Multi-pass encoding can not be used in live broadcast or live streaming. Multi-pass encoding takes much longer than single-pass encoding, because every pass means one pass through the input data.
Multi-pass encoding is used only for VBR encoding, because CBR encoding doesn't offer any flexibility to change the bitrate. The most common multi-pass encoding is two-pass encoding. In the first pass of two-pass encoding, the input data is being analyzed and the result is stored in a log file. In the second pass, the collected data from the first pass is used to achieve the best encoding quality. In a video encoding, two-pass encoding is controlled by the average bitrate setting or by the bitrate range setting or by the target video file size setting. One means of VBR encoding is fixed quality encoding, it is single-pass encoding. The user specifies a given subjective quality value, the encoder allocates bits as needed to achieve the given level of quality; this ensures. A quality level has an associated bitrate range; the disadvantage of this encoding method is that the average bitrate will not be known ahead of time, achieving a certain average bitrate requires trial and error. This is more of a concern for video than for audio, since file sizes are much larger and encoding can take much longer.
This VBR encoding method allows the user to specify a bitrate range — a minimum and/or maximum allowed bitrate. Some encoders extend this method with an average bitrate; the minimum and maximum allowed bitrate set bounds. The disadvantage of this method is; the bitrate range is used in some fixed quality encoding methods, but without permission to change a particular bitrate. Average bitrate encoding may be used to ensure the output stream achieves a predictable long-term average bitrate; this is implemented using multi-pass encoding, where one or more initial passes are used to collect data on the stream, a final pass uses that data to achieve uniform quality at the specified average bitrate. Alternatively, periodic averaging may be used, either by performing ABR on smaller chunks of the output, or by reacting to fluctuations in the ABR by increasing or reducing the overall quality; these can
Robert Sands Schuyler written as R. S. Schuyler and as R. V. Schuyler, was a New York architect and religious leader who moved to Florida and joined political and civil organizations on Amelia Island, he served as Clerk of the City of Fernandina, was Chair of the Fernandina Library Association when it was established in 1891, was a lay reader at the Santa Fe, Episcopal congregation. Schuyler was born in New York City on March 6, 1830, he was educated and married in Troy, New York He was the son of Robert Schuyler and Lucinda Wood Schuyler. His paternal grandparents were Philip Jeremiah Schuyler, a U. S. Representative, Sarah Rutsen, his grandfather was the son of Philip Schuyler, a Revolutionary War General and U. S. Senator, Catherine Van Rensselaer, a member of the prominent Van Rensselaer family. During the U. S. Civil War, he served in the Union cavalry. In 1881, Schuyler and his wife moved to Florida, joining prominent political and civil organizations on Amelia Island, he served as Clerk of the City of Fernandina, was Chair of the Fernandina Library Association when it was established in 1891, was a lay reader at the Santa Fe, Episcopal congregation.
He designed churches in Santa Fe, Waldo, many in the Carpenter Gothic style. Carpenter Gothic architecture was developed by Richard Upjohn, whom Episcopal Bishop John Freeman Young of Florida had known while he was an assistant rector of Trinity Church in New York City. St. John's served as a model for various churches in Waldo, Fairbanks, as well as the St. Paul's By-The-Sea Episcopal Church in Pablo Beach which Schuyler designed in 1887. In Santa Fe, Schuyler designed St. John's Chapel on land donated by E. B. Ewing, he is credited with the Fairbanks House, the Tabby House, the Marcellus Williams Marcellus Williams House Williams House, all on Amelia Island's Fernandina Beach in Nassau County, Florida. The Fairbanks House belonged to George Rainsford Fairbanks and is listed on the National Register of Historic Places. George Fairbanks House Tabby House 7th and Ash Streets 1886 School House Hirth House St. Andrew's Episcopal Church 317 Florida Avenue, Jacksonville Gothic Revival 1887. Only remaining church from before the 1901 fire.
St. Peters Church, Fernandina In 1864, Schuyler was married to Caroline E. Acker. Schuyler died in Fernandina, Florida on July 24, 1895
Burracoppin is a townsite on the Great Eastern Highway, east of Merredin in the Wheatbelt region of Western Australia. The town was gazetted in 1891, it takes its name from Burracoppin Rock, a nearby granite rock, the name of, first recorded in 1864 as Burancooping Rock. It was shown as Lansdowne Hill in 1836, it is an Aboriginal name said to mean "near a big hill". It is a stop on the Prospector rural railway service, it is the setting for the novel Mr Jelly's Business by Arthur W. Upfield, one in the series of Napoleon Bonaparte whodunits. Burracoppin is the site where the first Rabbit Proof Fence was started in 1901, with construction heading south to Esperance and north towards Port Hedland. Burracoppin was the main depot for the Rabbit Proof Fence. All gates through the fence and wells for the fence runners were numbered from this town. Parts of the original fence are still viewable in Burracoppin along with some of the original gates. In 1932 the Wheat Pool of Western Australia announced that the town would have two grain elevators, each fitted with an engine, installed at the railway siding.
The first was able to handle 1,800 bags of wheat per day. The main industry in town is wheat farming with the town being a Cooperative Bulk Handling receival site; the Prospector service, which runs each way between East Perth and Kalgoorlie once or twice each day, stops at Burracoppin. Media related to Burracoppin, Western Australia at Wikimedia Commons