Bosch DVR4C2161 Reference Guide - Page 35

325 Dig Sec Ref Guide-EN_03.qxd 02-12-2004 12:05 Pagina 35 35 Frequently asked questions What is wavelet compression and how does it differ from JPEG & MPEG? Wavelet compression is based on processing whole images one at a time. Redundant high frequency data is discarded, producing small data files and yet a pleasing image. JPEG and MPEG are Discrete Cosine Transform (DCT) methods that first divide the image into blocks of 8*8 pixels. These blocks can become apparent at high compression rates, MPEG, especially MPEG2 which is used for DVD's and Broadcast is ideal for normal video recording but is less suited to rapidly changing pictures, such as from multiplexers. Are images per second (ips) and frames per second (fps) different? Images per second and frames per second are both the same. They describe the video image that is stored. Is digital recording a reasonable alternative to analog recording? Yes, you can store many more images with more hours of recording on a small 80 GB hard drive than on an analog VCR using E-180 or E-240 tapes, even using recorders in high density mode. With 160 Gb or 320 Gb disk units, unattended recording becomes a reality. How can I get a permanent copy of a video clip for evidential purposes? The easiest and best method is to burn a CD-ROM by directly connecting a CD-ROM burner to the recorder or more often via a PC. Together with the video, a dedicated viewer will be put on the CD-ROM. Authentication ensures that the clip has not been corrupted or tampered with.