US 4,908,697 A · Two-line mac high definition television system

Abstract

A high definition television signal with a sequential scan with the standard number of lines per frame and double the frame frequency is processed to generate a single MAC line having a duration substantially equal to that of four sequential lines of standard duration. Each MAC line has two luminance components having different compression ratios. For the remaining two lines, compressed line difference signals are transmitted, thereby allowing reconstruction of all luminance lines at the receiver. Each MAC line further has a U chrominance component and a V chrominance component, alternatively compressed 1:4 and 1:2. The remaining parts of each MAC line are taken up by data signals and audio as well as the necessary clamping. The luminance and chrominance signals are prefiltered to prevent artifacts. The filtering is geared to the visual characteristics of the human visual system, i.e. diagonal spatial frequencies are subjected to more filtering then either purely horizontal or purely vertical spatial frequencies.

Claims23

Dependent claims

Method of encoding a high definition television signal having a predetermined number of frames per second, each frame having a plurality of HDTV lines each having a first line period, each HDTV line comprising a luminance component having a predetermined luminance bandwidth and at least one chrominance component, for transmission or recording with a channel bandwidth less than said luminance bandwidth, comprising the steps of:

processing said plurality of HDTV lines in groups, each group containing information from a multiplicity of sequential HDTV lines, to generate a plurality of signal packets, said signal packets comprising a first luminance component from a first HDTV line having a first time compression ratio, a second luminance component from a second HDTV line having a second time compression ratio, the second time compression ratio being different from said first time compression ratio, a plurality of line difference components and at least one chrominance component separate from said luminance components;
and
generating a time multiplexed line signal having a second line period greater than said first line period by time multiplexing said signal packets in time slots thereof.

Apparatus for encoding a high definition television signal having a predetermined number of frames per second, each frame having a plurality of HDTV lines each having a first line period, each HDTV line comprising a luminance component having a predetermined luminance bandwidth and at least one chrominance component, for transmission or recording with a channel bandwidth less than said luminance bandwidth, comprising:

means for processing said plurality of HDTV lines in groups, each group containing information from a multiplicity of sequential HDTV lines, to generate a plurality of signal packets, said signal packets comprising a first luminance component from a first HDTV line having a first time compression ratio a second luminance component from a second HDTV line having a second time compression ratio, the second time compression ratio being different from said first time compression ratio, a plurality of line difference components and at least one chrominance component separate from said luminance components;
and
means coupled to said processing means for generating a time multiplexed line signal having a second line period greater than said first line period by time multiplexing said signal packets in time slots thereof.

Dependencies are inferred from the claim text.

Two-line mac high definition television system

Life of this patent

Two-line mac high definition television system

Life of this patent

Abstract

Claims23