Efficient coding scheme for multilevel video transmission
First Claim
1. A signal coder for coding an input video signal into a basic layer signal and at least one contribution layer signal, a video signal having a spatial resolution lower than the spatial resolution of the input video signal being reconstructible from the basic layer signal, and a video signal having a spatial resolution higher than the lower spatial resolution and up to the resolution of the input video signal being reconstructible from the combination of the basic layer signal and the at least one contribution layer signal, the signal coder comprising:
- means for receiving an input signal consisting of pel values of a scanned video signal, said video signal consisting of sequential video frames,means for filtering the video signal to produce a baseband sequence of filtered pel values for each video frame,interframe hybrid transform/differential pulse code modulation coding means for coding the baseband sequence of filtered pel values for each video frame to form the basic layer signal,means for forming a differential video signal of each frame from the difference between the pel values in a current video frame and predicted pel values derived from the pel values in a previous coded video frame,means for decomposing the differential video signal of each frame into plural subband sequences of filtered differential pel values,means for separately quantizing and entropy coding the plural subband sequences of filtered differential pel values, andmeans for combining at least some of the quantized and encoded subband sequences of filtered differential pel values to form the at least one contribution layer signal.
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Abstract
A highly efficient video coding scheme is disclosed which codes, for transmission, the pel values of a scanned high quality HDTV video signal in such a manner that a low-quality version of the signal as well as a high-quality version are available to different video subscribers. The coder includes a basic layer coder (110) and a contribution layer encoder (150). A subscriber to a low-quality video service receives only the basic layer signal while a high-quality video subscriber receives both the basic layer signal and the contribution layer signal, which when combined together enable the high quality video signal to be reconstructed. The basic layer coder codes the baseband of a frequency decomposed video signal using a hybrid discrete cosine transform/differential pulse code modulation coding structure, such as the CCITT recommended H.261 coder. The contribution layer coder decomposes (123) a differential high quality video signal and separately quantizes (124) and entropy codes (125) the decomposed differential subbands other than the baseband, which are then multiplexed (126) together to form the contribution layer signal. When the baseband is coded by the basic layer coder at a low bit rate, the quantization noise it introduces will deleteriously affect the quality of a high quality signal "built" upon it. A residual signal component is therefore included within the contribution layer signal. This residual layer component, which is derived in part from the basic layer coder, enables the quantization noise introduced into the basic layer to be substantially eliminated when the basic layer signal is combined with the contribution layer signal to reconstruct the high quality video signal at a receiver/decoder.
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Citations
15 Claims
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1. A signal coder for coding an input video signal into a basic layer signal and at least one contribution layer signal, a video signal having a spatial resolution lower than the spatial resolution of the input video signal being reconstructible from the basic layer signal, and a video signal having a spatial resolution higher than the lower spatial resolution and up to the resolution of the input video signal being reconstructible from the combination of the basic layer signal and the at least one contribution layer signal, the signal coder comprising:
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means for receiving an input signal consisting of pel values of a scanned video signal, said video signal consisting of sequential video frames, means for filtering the video signal to produce a baseband sequence of filtered pel values for each video frame, interframe hybrid transform/differential pulse code modulation coding means for coding the baseband sequence of filtered pel values for each video frame to form the basic layer signal, means for forming a differential video signal of each frame from the difference between the pel values in a current video frame and predicted pel values derived from the pel values in a previous coded video frame, means for decomposing the differential video signal of each frame into plural subband sequences of filtered differential pel values, means for separately quantizing and entropy coding the plural subband sequences of filtered differential pel values, and means for combining at least some of the quantized and encoded subband sequences of filtered differential pel values to form the at least one contribution layer signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for coding a input video signal into a basic layer signal and at least one contribution layer signal, the input video signal consisting of sequential video frames, a video signal having a spatial resolution lower than the spatial resolution of the input video signal being reconstructible from the basic layer signal, and a video signal having a spatial resolution higher than the lower spatial resolution and up to the resolution of the input video signal being reconstructible from the combination of the basic layer signal and the at least one contribution layer signal, the method comprising the steps of:
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filtering the input video signal to produce a baseband sequence of filtered pel values for each video frame, coding the baseband sequence of filtered pel values using an interframe hybrid transform/differential pulse code modulation coder to form the basic layer signal, forming a differential video signal of each frame from the difference between the pel values in a current video frame and predicted pel values derived from the pel values in a previous coded video frame, decomposing the differential video signal of each frame into plural subband sequences of filtered differential pel values, separately quantizing and encoding the plural subband sequences of filtered differential pel values, and combining at least some of the quantized and encoded subband sequences of filtered differential pel values to form the at least one contribution layer signal. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification