Intra-Frame

With the use of prediction for video compression ( inter-frame coding) the intra- frame or keyframe (English Intra coded frame or key frame ) is in a group of inter-dependent images ( images group, Eng. Group of Pictures, GoP ) the independent decodable image on which the forecast for the rest of the chain (P and B ) based images. It is a completely described still image and also serves as the anchor for random access.

The contrast intra- frames to put the building on inter- frame prediction dar. of those there are two kinds, the P and B pictures. In addition to these is an intra picture is the most memory-intensive type, there are no direct image data, but merely reference indication and motion vector must be stored by referencing to corresponding image regions that are significantly smaller in the rule. Often, at least enforced in the encoded video, a minimum frequency of I-frames in order to keep the amount for random access ( for example, entry into a stream ) to be decoded pictures in a safe setting. MPEG -1 and 2, there is typically an intra picture per half second, for MPEG -4 times every ten seconds in a. From H.264 can a group of images containing multiple I-frames.

Mainly for use with video cameras, there are video codecs, which are limited to the use of intra- pictures:

• AVC- Intra ( subset of H.264)
• DVCAM
• MiniDV
• Motion JPEG

They are coded with little computational effort, in the image quality regardless of image motion and randomly accessible, but require a comparatively large space, as no consideration of the similarities to the previous or subsequent frames is taken.

• Video Compression