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Comparison Of Video Codecs
Α video codec is software or a device that provides encoding and decoding for digital video, and which may or may not include the use of video compression and/or decompression. Most codecs are typically implementations of video coding formats. The compression may employ lossy data compression, so that quality-measurement issues become important. Shortly after the compact disc became widely available as a digital-format replacement for analog audio, it became feasible to also store and use video in digital form. A variety of technologies soon emerged to do so. The primary goal for most methods of compressing video is to produce video that most closely approximates the fidelity of the original source, while simultaneously delivering the smallest file-size possible. However, there are also several other factors that can be used as a basis for comparison. Introduction to comparison The following characteristics are compared in video codecs comparisons: * Video quality per bitrate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Video Codec
A video codec is software or hardware that compresses and decompresses digital video. In the context of video compression, ''codec'' is a portmanteau of ''encoder'' and ''decoder'', while a device that only compresses is typically called an '' encoder'', and one that only decompresses is a ''decoder''. The compressed data format usually conforms to a standard video coding format A video coding format (or sometimes video compression format) is a content representation format for storage or transmission of digital video content (such as in a data file or bitstream). It typically uses a standardized video compression algori .... The compression is typically lossy compression, lossy, meaning that the compressed video lacks some information present in the original video. A consequence of this is that decompressed video has lower quality than the original, uncompressed video because there is insufficient information to accurately reconstruct the original video. There are complex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Streaming SIMD Extensions
In computing, Streaming SIMD Extensions (SSE) is a single instruction, multiple data (SIMD) instruction set extension to the x86 architecture, designed by Intel and introduced in 1999 in their Pentium III series of Central processing units (CPUs) shortly after the appearance of Advanced Micro Devices (AMD's) 3DNow!. SSE contains 70 new instructions (65 unique mnemonics using 70 encodings), most of which work on single precision floating-point data. SIMD instructions can greatly increase performance when exactly the same operations are to be performed on multiple data objects. Typical applications are digital signal processing and graphics processing. Intel's first IA-32 SIMD effort was the MMX instruction set. MMX had two main problems: it re-used existing x87 floating-point registers making the CPUs unable to work on both floating-point and SIMD data at the same time, and it only worked on integers. SSE floating-point instructions operate on a new independent register set, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MMX (instruction Set)
MMX is a ''single instruction, multiple data'' (SIMD) instruction set architecture designed by Intel, introduced on January 8, 1997 with its Pentium P5 (microarchitecture) based line of microprocessors, named "Pentium with MMX Technology". It developed out of a similar unit introduced on the Intel i860, and earlier the Intel i750 video pixel processor. MMX is a processor supplementary capability that is supported on IA-32 processors by Intel and other vendors . The New York Times described the initial push, including Super Bowl advertisements, as focused on "a new generation of glitzy multimedia products, including videophones and 3-D video games." MMX has subsequently been extended by several programs by Intel and others: 3DNow!, Streaming SIMD Extensions (SSE), and ongoing revisions of Advanced Vector Extensions (AVX). Overview Naming MMX is officially a meaningless initialism trademarked by Intel; unofficially, the initials have been variously explained as standing for * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SIMD
Single instruction, multiple data (SIMD) is a type of parallel processing in Flynn's taxonomy. SIMD can be internal (part of the hardware design) and it can be directly accessible through an instruction set architecture (ISA), but it should not be confused with an ISA. SIMD describes computers with multiple processing elements that perform the same operation on multiple data points simultaneously. Such machines exploit data level parallelism, but not concurrency: there are simultaneous (parallel) computations, but each unit performs the exact same instruction at any given moment (just with different data). SIMD is particularly applicable to common tasks such as adjusting the contrast in a digital image or adjusting the volume of digital audio. Most modern CPU designs include SIMD instructions to improve the performance of multimedia use. SIMD has three different subcategories in Flynn's 1972 Taxonomy, one of which is SIMT. SIMT should not be confused with software thr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frames Per Second
A frame is often a structural system that supports other components of a physical construction and/or steel frame that limits the construction's extent. Frame and FRAME may also refer to: Physical objects In building construction *Framing (construction), a building term known as light frame construction *Framer, a carpenter who assembles major structural elements in constructing a building *A-frame, a basic structure designed to bear a load in a lightweight economical manner **A-frame house, a house following the same principle *Door frame or window frame, fixed structures to which the hinges of doors or windows are attached *Frame and panel, a method of woodworking *Space frame, a method of construction using lightweight or light materials *Timber framing, a method of building for creating framed structures of heavy timber or willow wood In vehicles *Frame (aircraft), structural rings in an aircraft fuselage *Frame (nautical), the skeleton of a boat *Bicycle frame, the main c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sum Of Absolute Differences
In digital image processing, the sum of absolute differences (SAD) is a measure of the similarity between image blocks. It is calculated by taking the absolute difference between each pixel in the original block and the corresponding pixel in the block being used for comparison. These differences are summed to create a simple metric of block similarity, the ''L''1 norm of the difference image or Manhattan distance between two image blocks. The sum of absolute differences may be used for a variety of purposes, such as object recognition, the generation of disparity maps for stereo images, and motion estimation for video compression. Example This example uses the sum of absolute differences to identify which part of a search image is most similar to a template image. In this example, the template image is 3 by 3 pixels in size, while the search image is 3 by 5 pixels in size. Each pixel is represented by a single integer from 0 to 9. Template Search image 2 5 5 2 7 5 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peak Signal-to-noise Ratio
Peak signal-to-noise ratio (PSNR) is an engineering term for the ratio between the maximum possible power of a signal and the power of corrupting noise that affects the fidelity of its representation. Because many signals have a very wide dynamic range, PSNR is usually expressed as a logarithmic quantity using the decibel scale. PSNR is commonly used to quantify reconstruction quality for images and video subject to lossy compression. Definition PSNR is most easily defined via the mean squared error (''MSE''). Given a noise-free ''m''×''n'' monochrome image ''I'' and its noisy approximation ''K'', ''MSE'' is defined as : \mathit = \frac\sum_^\sum_^ (i,j) - K(i,j)2. The PSNR (in dB) is defined as : \begin \mathit &= 10 \cdot \log_ \left( \frac \right) \\ &= 20 \cdot \log_ \left( \frac \right) \\ &= 20 \cdot \log_(\mathit_I) - 10 \cdot \log_ (\mathit). \end Here, ''MAXI'' is the maximum possible pixel value of the image. When the pixels are represented using 8 bits per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Video Denoising
Video denoising is the process of removing noise from a video signal. Video denoising methods can be divided into: * Spatial video denoising methods, where image noise reduction is applied to each frame individually. * Temporal video denoising methods, where noise between frames is reduced. Motion compensation may be used to avoid ghosting artifacts when blending together pixels from several frames. * Spatial-temporal video denoising methods use a combination of spatial and temporal denoising. This is often referred to as 3D denoising. It is done in two areas: They are chroma and luminance, chroma noise is where one see color fluctuations and luminance is where one see light/dark fluctuations. Generally, the luminance noise looks more like film grain while chroma noise looks more unnatural or digital like. Video denoising methods are designed and tuned for specific types of noise. Typical video noise types are following: * Analog noise ** Radio channel artifacts *** High frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mean Opinion Score
Mean opinion score (MOS) is a measure used in the domain of Quality of Experience and telecommunications engineering, representing overall quality of a stimulus or system. It is the arithmetic mean over all individual "values on a predefined scale that a subject assigns to his opinion of the performance of a system quality". Such ratings are usually gathered in a subjective quality evaluation test, but they can also be algorithmically estimated. MOS is a commonly used measure for video, audio, and audiovisual quality evaluation, but not restricted to those modalities. ITU-T has defined several ways of referring to a MOS in RecommendatioITU-T P.800.1 depending on whether the score was obtained from audiovisual, conversational, listening, talking, or video quality tests. Rating scales and mathematical definition The MOS is expressed as a single rational number, typically in the range 1–5, where 1 is lowest perceived quality, and 5 is the highest perceived quality. Other MOS ranges ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constant Bitrate
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 en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Key Frame
In animation and filmmaking, a key frame (or keyframe) is a drawing or shot that defines the starting and ending points of a smooth transition. These are called ''frames'' because their position in time is measured in frames on a strip of film or on a digital video editing timeline. A sequence of key frames defines which movement the viewer will see, whereas the position of the key frames on the film, video, or animation defines the timing of the movement. Because only two or three key frames over the span of a second do not create the illusion of movement, the remaining frames are filled with " inbetweens". Use of key frames as a means to change parameters In software packages that support animation, especially 3D graphics, there are many parameters that can be changed for any one object. One example of such an object is a light (In 3D graphics, lights function similarly to real-world lights. They cause illumination, cast shadows, and create specular highlights). Lights have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
