Glossary

Representation of an image width to its height. A general notation is the form of X:Y where X represent the image width and Y represent the image height.While there are several video standards that are currently used in video applications, it is necessary to keep aspect ratio stable when converting ...

Rate of bits transmitted over a particular period of time on a specific channel.In video coding applications, video bit rate is determined by the number of the used bits per one second.For example: 1Mbps = 1Megabit (1 Million bits) per second.

FPS stands for Frames Per Second. It indicates the rate of frames used in one second of video stream. The most common frame rate today for video communiation is 30 fps.

A term defining the size of the basic element of video content – the frame.Frame resolution describes the number of pixels on the horizontal and vertical axis of a video frame.There are several predefined popular acronyms for frame resolutions: CIF – 352×288, 4CIF – 704×576, D1 – 720×480 (NTSC) or ...

A term used to describe the variation in packet delay. In packet switch applications, where data is carrying over network packets, there is a variance in the packet arrival timing. In order to overcome this variance and to provide a smooth usage of the received packets, a delay buffer is ...

A term used to refer to the relative timing of audio and video portions during playback. In general, it used to describe the matching of lip movements with voice. Generally, human perception is sensitive to non synchronized audio and video with a relative phase of ~100 msec. In contrast, there ...

A term used to describe a compression method where the compressed data cannot be reconstructed exactly as the original form. This type of compression is mainly used in visual and audio applications where a partial loss of data is acceptable by the human visual and hearing systems. As opposed to ...

Packets are units of information sent across a packet switched network from their source address to a destination. Packet loss occurs when one or more packets fail to reach their destination. On network protocols such as UDP that provide no recovery mechanism for packet loss, applications should handle that error ...

"Talking heads" is a term usually used to define a point-to-point video calling scenario, where the video displayed shows both people on from the shoulders and up. At its core, it is the most basic layout for video telephony, often considered as not compelling enough for more advanced video calling ...

Transcoding is the conversion of one transmission format into another using various algorithms to achieve wider support of formats at different quality levels.In the context of video communications, transcoding will usually take place between video codec formats and voice codec formats.The operation of transcoding brings with it several challenges:Transcoding increaes ...

Transrating means changing the bitrate (bandwidth) of a stream by means of processing. For instance, processing an input video stream of 1Mbps so that the output stream is 256Kbps only. Transrating can increase or decrease the bitrate, and usually involves changing the encoding parameters (usually quantization).See also: Transcoding

The big challenge in most video applications is to provide the highest video quality with a minimum cost of bit rate. As a result of lossy compression techniques, non optimized network conditions and other application restrictions, video quality is affected and quality of service may reduce. Video artifacts may be ...

Software or hardware device that enables video decompression. In general, a video decoder is used to reconstruct the video content from compressed data into a visible displayed format. For real time streaming network applications, the decoder is used to convert video packets sent over the network into video frames which ...

Software or hardware device that enables video compression. Generally, compression is used to reduce the size of the visual content, either for storage purposes or for streaming over a network channel (reduce bit rate). Video encoder performance and quality is being determined by the encoder complexitySee also: Video Decoder