MPEG-1 MPEG-1 demand 10 Mbps Medium 100 Mbps lan MPEG-2/4 MPEG-2/4 MPEG-7 Video phone 64 kbps High distortion ISDN X 64 H.261 encoder H.261 h.261 decoder Desktop multimedia 1.5 Mbps High distortion to PC channel MPEG-1 decoder MPEG-1 video CDROM medium MPEG-2 MPEG-7 Desktop LAN 10 Mbps Medium distortion Fast ethernet Hardware decoders MPEG-2/4, videoconference 100 Mbps H.261 Desktop WAN 1.5 Mbps High distortion Ethernet Hardware decoders MPEG-1, videoconference MPEG-4, H.263 Desktop dial-up 64 kbps Very high distortion POTS and internet Software decoder MPEG-4, videoconference H.263 Digital satellite 10 Mbps Low distortion Fixed service MPEG-2 decoder MPEG-2 television satellites 20 Mbps Low distortion 12 MHz terrestrial MPEG-2 decoder MPEG-2 20 Mbps Low distortion PC channel MPEG-2 decoder MPEG-2 Fig. 7.4-2 depicts the magnitude L of the Fourier meet the Nyquist criteria for most resolution and appli- spectrum for l. The magnitude of the Fourier spectrum cation requirements. The electrical characteristics of Ls for the sampled signal ls is shown for two cases. CCDs have a greater affect on the image or video quality Diagram (b) presents the case where the original signal l than its sampling grid size. can be reconstructed by recovering the central spectral Temporal sampling of video signals is accomplished by island. Diagram (c) displays the case where the Nyquist capturing a spatial or image frame in the time dimension. sampling criteria has not been met and spectral overlap The temporal samples are captured at a uniform rate of occurs. The spectral overlap is termed aliasing and about 60 fields per second for NTSC television and occurs when fs < 2fB. When fs > 2fB, the original signal 24 fps for a motion film recording. These sampling rates can be reconstructed by using a low pass digital filter are significantly less than the spatial sampling rate. The whose pass band is designed to recover L These maximum temporal frequency that can be reconstructed relationships provide a basic framework for the analysis ac