All video signals transmitted from Network Cameras and Servers must be compressed, transmitted and then decompressed. There are two primary standards for video compression: MJPEG (Motion JPEG). In this format the video stream is sent as a series of still images (frames), rather like a traditional cartoon. The compression takes place within each individual frame. Each individual frame is a standalone JPEG image which can easily be used for evidential purposes. MJPEG makes it relatively easy to view live images in a fast frame-rate and to record them at a lower rate. Most network Cameras and Servers offer MJPEG compression. MPEG-4. Many network cameras offer this compression method as well as MJPEG, a few offer just MPEG-4. MPEG-4 compression offers much more efficient use of bandwidth and can be used for multi-casting. However, the compression takes place between frames, ie just taking account of the changes from one frame to the next. This offers better viewing at lower bandwidth utilisation, but is not recommended for security applications because a still iamge can be difficult to verify for evidential purposes. H.264 is a new compression method similar to MPEG-4 but with even better compression. This is used in a few network cameras, but viewing platforms for this compression method are limited at the moment.