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Video Buffering Verifier
The Video Buffering Verifier (VBV) is a theoretical MPEG video buffer model, used to ensure that an encoded video stream can be correctly buffered, and played back at the decoder device. By definition, the VBV shall not overflow nor underflow when its input is a compliant stream, (except in the case of low_delay). It is therefore important when encoding such a stream that it comply with the VBV requirements. One way to think of the VBV is to consider both a maximum bitrate and a maximum buffer size. You'll need to know how quickly the video data is coming into the buffer. Keep in mind that video data is always changing the bitrate so there is no constant number to note how fast the data is arriving. The larger question is how long before the buffer overflows. A larger buffer size simply means that the decoder will tolerate high bitrates for longer periods of time, but no buffer is infinite, so eventually even a large buffer will overflow. Operation Modes There are two operational ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MPEG
The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by International Organization for Standardization, ISO and International Electrotechnical Commission, IEC that sets standards for media coding, including compression coding of audio compression (data), audio, video compression, video, graphics, and Compression of Genomic Sequencing Data, genomic data; and transmission and Container format (digital), file formats for various applications.John Watkinson, ''The MPEG Handbook'', p. 1 Together with Joint Photographic Experts Group, JPEG, MPEG is organized under ISO/IEC JTC 1/ISO/IEC JTC 1/SC 29, SC 29 – ''Coding of audio, picture, multimedia and hypermedia information'' (ISO/IEC Joint Technical Committee 1, Subcommittee 29). MPEG formats are used in various multimedia systems. The most well known older MPEG media formats typically use MPEG-1, MPEG-2, and MPEG-4 AVC media coding and MPEG-2 systems MPEG transport stream, transport streams an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constant Bit Rate
Constant bitrate (CBR) is a term used in telecommunications, relating to the quality of service. Compare with variable bitrate. When referring to codecs, constant bit rate encoding means that the rate at which a codec's output data should be consumed is constant. CBR is useful for streaming multimedia content on limited capacity channels since it is the maximum bit rate that matters, not the average, so CBR would be used to take advantage of all of the capacity. CBR is not optimal for storing data as it may not allocate enough data for complex sections (resulting in degraded quality); and if it maximizes quality for complex sections, it will waste data on simple sections. The problem of not allocating enough data for complex sections could be solved by choosing a high bitrate to ensure that there will be enough bits for the entire encoding process, though the size of the file at the end would be proportionally larger. Most coding schemes such as Huffman coding or run-length enco ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Variable Bit Rate
Variable bitrate (VBR) is a term used in telecommunications and computing that relates to the bitrate used in sound or video encoding. As opposed to constant bitrate (CBR), VBR files vary the amount of output data per time segment. VBR allows a higher bitrate (and therefore more storage space) 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 also commonly used on MPEG-2 video, MPEG-4 Part 2 video ( Xvid, DivX, etc.), MPEG-4 Part 10/H.264 video, Theora, Dirac and other video compression formats. Additionally, variable rate encoding is inherent in lossless compression schemes such as FLAC and Apple Lossless. Advantages and disadvantages of VBR The advantages of VBR a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VC-1
SMPTE 421, informally known as VC-1, is a video coding format. Most of it was initially developed as Microsoft's proprietary video format Windows Media Video 9 in 2003. With some enhancements including the development of a new Advanced Profile, it was officially approved as an SMPTE standard on April 3, 2006. It was primarily marketed as a lower-complexity competitor to the H.264/MPEG-4 AVC standard. After its development, several companies other than Microsoft asserted that they held patents that applied to the technology, including Panasonic, LG Electronics and Samsung Electronics. VC-1 is supported in the now-deprecated Microsoft Silverlight, the briefly-offered HD DVD disc format, and the Blu-ray Disc format. Format VC-1 is an evolution of the conventional block-based motion-compensated hybrid video coding design also found in H.261, MPEG-1 Part 2, H.262/MPEG-2 Part 2, H.263, and MPEG-4 Part 2. It was widely characterized as an alternative to the ITU-T and MPEG video ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Film And Video Technology
A film, also known as a movie or motion picture, is a work of visual art that simulates experiences and otherwise communicates ideas, stories, perceptions, emotions, or atmosphere through the use of moving images that are generally, since the 1930s, synchronized with sound and (less commonly) other sensory stimulations. Etymology and alternative terms The name "film" originally referred to the thin layer of photochemical emulsion on the celluloid strip that used to be the actual medium for recording and displaying motion pictures. Many other terms exist for an individual motion-picture, including "picture", "picture show", "moving picture", "photoplay", and "flick". The most common term in the United States is "movie", while in Europe, "film" is preferred. Archaic terms include "animated pictures" and "animated photography". "Flick" is, in general a slang term, first recorded in 1926. It originates in the verb flicker, owing to the flickering appearance of early films. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
