发明授权
US4212028A Processing pal color television signals 失效
处理彩色电视信号

Processing pal color television signals
摘要:
In a method and apparatus for transcoding digital PAL color television signals between (i) a 2fsc format consisting of an encoded signal of PAL type sampled at 2fsc and (ii) a 3fsc format consisting of a luminance signal Y at 2fsc and a chrominance signal C sampled at fsc and comprising U+V and U-V on alternate lines (or either the luminance signal or composite chrominance signal by itself), avoid the need to convert the signal to analogue PAL form as an intermediate step. Converting from the 2fsc to the 3fsc format, over the chrominance bandwidth undelayed and 1- and 2-line delayed samples are combined in the proportions 1/4:1/2:1/4, and below the chrominance band the 1-line delayed samples are low-pass filtered, these together providing the luminance signal Y. To provide the chrominance signal C the undelayed and 2-line delayed signals are combined in the proportions -1/4:1/4. The low- and band-pass filters are digital transversal filters operating on adjacent samples in the signal. Transcoding in the other direction is similar.
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