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Audio Synchronizer
An audio synchronizer is a variable audio delay used to correct or maintain audio-video sync or timing also known as lip sync error. See for example the specification for audio to video timing given in ATSC Document IS-191. Modern television systems use large amounts of video signal processing such as MPEG preprocessing, encoding and decoding, video synchronization and resolution conversion in pixelated displays. This video processing can cause delays in the video signal ranging from a few microseconds to tens of seconds. If the television program is displayed to the viewer with this video delay the audio-video synchronization is wrong, and the video will appear to the viewer after the sound is heard. This effect is commonly referred to as A/V sync or lip sync error and can cause serious problems related to the viewer's enjoyment of the program. Error correction To correct audio video sync problems, the video processing circuitry outputs a DDO (digital delay output) signal, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sound Recording And Reproduction
Sound recording and reproduction is the electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording. Sound recording is the transcription of invisible vibrations in air onto a storage medium such as a phonograph disc. The process is reversed in sound reproduction, and the variations stored on the medium are transformed back into sound waves. Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, which is then converted to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pixelated
Pixelization (British English, pixelisation) or mosaic processing is any technique used in editing images or video, whereby an image is blurred by displaying part or all of it at a markedly lower resolution. It is primarily used for censorship. The effect is a standard graphics filter, available in all but the most basic bitmap graphics editors. As censorship A familiar example of pixelization can be found in majority of television news and documentary productions, in which vehicle license plates and faces of suspects at crime scenes are routinely obscured to maintain the presumption of innocence, such as how it appears in the television series '' COPS''. This is especially used in Hungary and Slovakia by RTL Klub. Bystanders and others who do not sign release forms are also customarily pixelized. Footage of nudity (including male and female genitals, buttocks, nipples, pubic hair, or areolae) is likewise obscured in some media: before the watershed in many countries, in new ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio To Video Synchronization
Audio-to-video synchronization (AV synchronization, also known as lip sync, or by the lack of it: lip-sync error, lip flap) refers to the relative timing of audio (sound) and video (image) parts during creation, post-production (mixing), transmission, reception and play-back processing. AV synchronization can be an issue in television, videoconferencing, or film. In industry terminology, the lip-sync error is expressed as an amount of time the audio departs from perfect synchronization with the video where a positive time number indicates the audio leads the video and a negative number indicates the audio lags the video. This terminology and standardization of the numeric lip-sync error is utilized in the professional broadcast industry as evidenced by the various professional papers, standards such as ITU-R BT.1359-1, and other references below. Digital or analog audio video streams or video files usually contain some sort of synchronization mechanism, either in the form of in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SMPTE Timecode
SMPTE timecode ( or ) is a set of cooperating standards to label individual frames of video or film with a timecode. The system is defined by the Society of Motion Picture and Television Engineers in the SMPTE 12M specification. SMPTE revised the standard in 2008, turning it into a two-part document: SMPTE 12M-1 and SMPTE 12M-2, including new explanations and clarifications. Timecodes are added to film, video or audio material, and have also been adapted to synchronize music and theatrical production. They provide a time reference for editing, synchronization and identification. Timecode is a form of media metadata. The invention of timecode made modern videotape editing possible and led eventually to the creation of non-linear editing systems. Basic concepts SMPTE timecode is presented in ''hour:minute:second:frame'' format and is typically represented in 32 bits using binary-coded decimal. There are also ''drop-frame'' and ''color framing'' flags and three extra ''binary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Video Processing
In electronics engineering, video processing is a particular case of signal processing, in particular image processing, which often employs video filters and where the input and output signals are video files or video streams. Video processing techniques are used in television sets, VCRs, DVDs, video codecs, video players, video scalers and other devices. For example—commonly only design and video processing is different in TV sets of different manufactures. Video processor Video processors are often combined with video scalers to create a video processor that improves the apparent definition of video signals. They perform the following tasks: * deinterlacing * aspect ratio control * digital zoom and pan * brightness/ contrast/hue/saturation/ sharpness/gamma adjustments * frame rate conversion and inverse-telecine * color point conversion (601 to 709 or 709 to 601) * color space conversion ( YPBPR/ YCBCR to RGB or RGB to YPBPR/YCBCR) * mosquito noise reduction * block noise ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Delay (audio Effect)
Delay is an audio signal processing technique that records an input signal to a storage medium and then plays it back after a period of time. When the delayed playback is mixed with the live audio, it creates an echo-like effect, whereby the original audio is heard followed by the delayed audio. The delayed signal may be played back multiple times, or fed back into the recording, to create the sound of a repeating, decaying echo. Delay effects range from a subtle echo effect to a pronounced blending of previous sounds with new sounds. Delay effects can be created using tape loops, an approach developed in the 1940s and 1950s and used by artists including Elvis Presley and Buddy Holly. Analog effects units were introduced in the 1970s; digital effects pedals in 1984; and audio plug-in software in the 2000s. History The first delay effects were achieved using tape loops improvised on reel-to-reel audio tape recording systems. By shortening or lengthening the loop of tape and adj ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lip Sync
Lip sync or lip synch (pronounced , the same as the word ''sink'', short for lip synchronization) is a technical term for matching a speaking or singing person's lip movements with sung or spoken vocals. Audio for lip syncing is generated through the sound reinforcement system in a live performance or via television, computer, cinema speakers, or other forms of audio output. The term can refer to any of a number of different techniques and processes, in the context of live performances and audiovisual recordings. In film production, lip syncing is often part of the post-production phase. Dubbing foreign-language films and making animated characters appear to speak both require elaborate lip syncing. Many video games make extensive use of lip-synced sound files to create an immersive environment in which on-screen characters appear to be speaking. In the music industry, lip syncing is used by singers for music videos, television and film appearances and some types of live perf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchronization In Telecommunications
Many services running on modern digital telecommunications networks require accurate synchronization for correct operation. For example, if telephone exchanges are not synchronized, then bit slips will occur and degrade performance. Telecommunication networks rely on the use of highly accurate primary reference clocks which are distributed network-wide using synchronization links and synchronization supply units. Ideally, clocks in a telecommunications network are synchronous, controlled to run at identical rates, or at the same mean rate with a fixed relative phase displacement, within a specified limited range. However, they may be mesochronous in practice. In common usage, mesochronous networks are often described as ''synchronous''. Components Primary reference clock (PRC) Modern telecommunications networks use highly accurate primary master clocks that must meet the international standards requirement for long term frequency accuracy better than 1 part in 1011. To get ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Video Synching
In video, frame synchronization is the process of synchronizing display pixel scanning to a synchronization source. When several systems are connected, a synchronization signal is fed from the synchronization source to the other systems in the network, and the video signals are synchronized with each other. A sync generator produces a central timing reference (usually a color black signal, also known as a black and burst) that is distributed throughout a facility. The central timing reference is used in video production to synchronize the timing of a video source signals. As a result, the timing or alignment of the video frame can be adjusted so that the start of the upper left corner scan line of the image occurs simultaneously on all video equipment in the network. This is an absolute requirement for both analog and digital systems in order to perform video effects or glitch-free source switching. See also * Genlock Genlock (generator locking) is a common technique where t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Audio Video Sync
Audio-to-video synchronization (AV synchronization, also known as lip sync, or by the lack of it: lip-sync error, lip flap) refers to the relative timing of audio (sound) and video (image) parts during creation, post-production (mixing), transmission, reception and play-back processing. AV synchronization can be an issue in television, videoconferencing, or film. In industry terminology, the lip-sync error is expressed as an amount of time the audio departs from perfect synchronization with the video where a positive time number indicates the audio leads the video and a negative number indicates the audio lags the video. This terminology and standardization of the numeric lip-sync error is utilized in the professional broadcast industry as evidenced by the various professional papers, standards such as ITU-R BT.1359-1, and other references below. Digital or analog audio video streams or video files usually contain some sort of synchronization mechanism, either in the form o ... [...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] |
Video
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) systems which, in turn, were replaced by flat panel displays of several types. Video systems vary in display resolution, aspect ratio, refresh rate, color capabilities and other qualities. Analog and digital variants exist and can be carried on a variety of media, including radio broadcast, magnetic tape, optical discs, computer files, and network streaming. History Analog video Video technology was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) television systems, but several new technologies for video display devices have since been invented. Video was originally exclusively a live technology. Charles Ginsburg led an Ampex research team developing one of the first practical vi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
