Apparatus for deriving a compatible low-definition interlaced television signal and other components for reconstructing the original signal from an interlaced high-definition television signal
First Claim
1. An apparatus for digitally processing a high definition television signal comprising interlaced first and second fields for digital recording or other signal transmission, said television signal comprising a main number of samples per field and having a main frequency range, said apparatus comprising:
- (a) filter means for horizontally and vertically filtering said television signal so as to provide first, second, third and fourth auxiliary signals having first, second, third and fourth horizontal/vertical frequency ranges respectively which in combination comprise said main frequency range, said filter means comprising at least one filter having an even length for filtering said first field and at least one filter having an odd length for filtering said second field;
(b) subsampling means coupled to said filter means, for subsampling said first, second, third and fourth auxiliary signals so as to provide first, second, third and fourth numbers of samples per field respectively, wherein the sum of said first, second, third and fourth numbers of samples per field does not exceed said main number of samples per field.
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Abstract
Apparatus for deriving a compatible low-definition interlaced television signal and other components for restructuring the original signal from an interlaced high-definition television signal. The HDTV signal is divided into four component signals by horizontal and vertical low-pass and high-pass QMF filtering. For the vertical filtering, one field of a frame is filtered by an odd-length filter, the other field by an even-length filter. A time delay of one sample is introduced before the high-pass odd-length QMF filter. The component signals are each subsampled by a factor of two after filtering. The component signal covering the low-frequency horizontal and low-frequency vertical range is a reduced definition interlaced TV signal. To reconstruct the original HDTV signal, all four component signals are upsampled and filtered and a one sample delay is introduced following the low-frequency odd-length filter.
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Citations
15 Claims
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1. An apparatus for digitally processing a high definition television signal comprising interlaced first and second fields for digital recording or other signal transmission, said television signal comprising a main number of samples per field and having a main frequency range, said apparatus comprising:
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(a) filter means for horizontally and vertically filtering said television signal so as to provide first, second, third and fourth auxiliary signals having first, second, third and fourth horizontal/vertical frequency ranges respectively which in combination comprise said main frequency range, said filter means comprising at least one filter having an even length for filtering said first field and at least one filter having an odd length for filtering said second field; (b) subsampling means coupled to said filter means, for subsampling said first, second, third and fourth auxiliary signals so as to provide first, second, third and fourth numbers of samples per field respectively, wherein the sum of said first, second, third and fourth numbers of samples per field does not exceed said main number of samples per field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification