A graphical user interface (GUI) is a type of user interface item that allows people to interact with programs in more ways than typing such as computers; hand-held devices such as MP3 Players, Portable Media Players or Gaming devices; household appliances and office equipment with images rather than text commands. A GUI offers graphical icons, and visual indicators, as opposed to text-based interfaces, typed command labels or text navigation to fully represent the information and actions available to a user. The actions are usually performed through direct manipulation of the graphical elements.
The term GUI is historically restricted to the scope of two-dimensional display screens with display resolutions capable of describing generic information, in the tradition of the computer science research at Palo Alto Research Center (PARC). The term GUI earlier might have been applicable to other high-resolution types of interfaces that are non-generic, such as videogames, or not restricted to flat screens, like volumetric displays. Read more about: Graphical user interface
Real Time Media Flow Protocol (RTMFP) is a proprietary protocol developed by Adobe Systems. RTMFP enables direct peer-to-peer communication between multiple Adobe Flash Players and applications built using the Adobe AIR framework for the delivery of rich, live, realâ€time communication.
By using RTMFP, applications that rely on live, realâ€time communications, such social networks and multiâ€user games will be able to deliver higher quality communication solutions. RTMFP enables endâ€users to connect and communicate directly with each other using their computerâ€™s microphone and webcam. RTMFP will not support file or document sharing. This solution enhances the current functionality in the Flash Player by creating a higher quality solution that will perform better regardless of variations in the network
RTMFP will reduce the bandwidth costs for direct, live, realâ€time communication solutions, such as audio and video chat and multiâ€player games. Because RTMFP flows data between the endâ€user clients and not the server, bandwidth is not being used at the server so solutions are less expensive to scale. RTMFP also increases the speed of delivery through the use of UDP. UDP is a more efficient (but less reliable) way to send video and audio data over the Internet that reduces the penalties associated with missing, dropped, or out of order packets. RTMFP has two features that may help to mitigate the effects of connection errors.
Rapid Connection Restore: Connections are reâ€established quickly after brief outages. For example, when a wireless network connection experiences a dropout. After reconnection, the connection has full capabilities instantly.
IP Mobility: Active network peer sessions are maintained even if a client changes to a new IP address. For example, when a laptop on a wireless network is plugged into a wired connection and receives a Read more about: Real Time Media Flow Protocol
Versions of the H.264/AVC standard include the following completed revisions, corrigenda, and amendments (dates are final approval dates in ITU-T, while final "International Standard" approval dates in ISO/IEC are somewhat different and slightly later in most cases). Each version represents changes relative to the next lower version that is integrated into the text. Bold faced versions are published (or planned to be published).
* 1. Version (May 2003) First approved version of H.264/AVC containing Baseline, Extended, and Main profiles.
* 2. Version (May 2004) Corrigendum containing various minor corrections.
* 3. Version (March 2005) Major addition to H.264/AVC containing the first Amendment providing Fidelity Range Extensions (FRExt) containing High, High 10, High 4:2:2, and High 4:4:4 profiles.
* 4. Version (September 2005) Corrigendum containing various minor corrections and adding three aspect ratio indicators.
* 5. Version (June 2006) Amendment consisting of removal of prior High 4:4:4 profile (processed as a corrigendum in ISO/IEC)
* 6. Version (June 2006) Amendment consisting of minor extensions like extended-gamut color space support (bundled with above-mentioned aspect ratio indicators in ISO/IEC).
* 7. Version (April 2007) Amendment containing the addition of High 4:4:4 Predictive and four Intra-only profiles (High 10 Intra, High 4:2:2 Intra, High 4:4:4 Intra, and CAVLC 4:4:4 Intra).
* 8. Version (November 2007) Major addition to H.264/AVC containing the Amendment for Scalable Video Coding (SVC) containing Scalable Baseline, Scalable High, and Scalable High Intra profiles.
* 9. Version (January 2009) Corrigendum containing minor corrections.
H.264/AVC/MPEG-4 Part 10 contains a number of new features that allow it to compress video much more effectively than older standards and to provide more flexibility for application to a wide variety of network environments. In particular, some such key features include:
* Multi-picture inter-picture prediction including the following features:
o Using previously-encoded pictures as references in a much more flexible way than in past standards, allowing up to 16 reference frames (or 32 reference fields, in the case of interlaced encoding) to be used in some cases. This is in contrast to prior standards, where the limit was typically one; or, in the case of conventional "B pictures", two. This particular feature usually allows modest improvements in bit rate and quality in most scenes. But in certain types of scenes, such as those with repetitive motion or back-and-forth scene cuts or uncovered background areas, it allows a significant reduction in bit rate while maintaining clarity.
o Variable block-size motion compensation (VBSMC) with block sizes as large as 16 imes 16 and as small as 4 imes 4, enabling precise segmentation of moving regions. The supported luma prediction block sizes include 16 imes 16, 16 imes 8, 8 imes 16, 8 imes 8, 8 imes 4, 4 imes 8, and 4 imes 4, many of which can be used together in a single macroblock. Chroma prediction block sizes are correspondingly smaller according to the chroma subsampling in use.
o The ability to use multiple motion vectors per macroblock (one or two per partition) with a maximum of 32 in the case of a B macroblock constructed of 16 4 imes 4 partitions. The motion vectors for each 8 *8 or larger partition region can point to different reference pictures.
Read more about: H.264 Features
The intent of the H.264/AVC project was to create a standard capable of providing good video quality at substantially lower bit rates than previous standards (e.g. half or less the bit rate of MPEG-2, H.263, or MPEG-4 Part 2), without increasing the complexity of design so much that it would be impractical or excessively expensive to implement. An additional goal was to provide enough flexibility to allow the standard to be applied to a wide variety of applications on a wide variety of networks and systems, including low and high bit rates, low and high resolution video, broadcast, DVD storage, RTP/IP packet networks, and ITU-T multimedia telephony systems.
The H.264 standard is a "family of standards", the members of which are the profiles described below. A specific decoder decodes at least one, but not necessarily all, profiles. The decoder specification describes which of the profiles can be decoded.
The standardization of the first version of H.264/AVC was completed in May 2003. The JVT then developed extensions to the original standard that are known as the Fidelity Range Extensions (FRExt). These extensions enable higher quality video coding by supporting increased sample bit depth precision and higher-resolution color information, including sampling structures known as YUV 4:2:2 and YUV 4:4:4. Several other features are also included in the Fidelity Range Extensions project, such as adaptive switching between 4 *4 and 8 *8 integer transforms, encoder-specified perceptual-based quantization weighting matrices, efficient inter-picture lossless coding, and support of additional color spaces. The design work on the Fidelity Range Extensions was completed in July 2004, and the drafting work on them was completed in September 2004.
Further recent extensions of the standard have included adding five new profiles intended primarily for professional applications, adding extended-gamut color space support, defin Read more about: H.264 Overview