US 5,223,926 A · Compression of video signals

Abstract

A digital video signal is compressed by spatial sub-band filtering to form data sets constituting respective sub-bands of the two-dimensional spatial frequency domain. The data sets for a field or frame are stored. A first sequencer controls writing, in accordance with a desired sequence, of the stored data to a quantizer in which they are quantized in accordance with respective values, those values being such that the amount of quantization of at least a data set constituting a sub-band to which dc luminance information of the signal is at least predominantly confined is less than the average of the amounts of quantization of the remaining data sets. The quantized data sets are then encoded in an entropy encoder which has a first coding portion for coding quantized data representative of dc luminance information and a second coding portion for coding quantized data representative of ac luminance information. A second sequencer, which may be the same sequencer as the first sequencer, controls operation of the quantizer so that each datum (sample) written thereto is appropriately quantized, and controls operation of the entropy encoder so that each quantized sample is directed to the appropriate one of the first and second coding portions.

Claims42

Dependent claims

A method of compressing a video signal, the method comprising the steps of:

effecting spatial two-dimensional sub-band filtering of a digital video signal to form a plurality of data sets constituting respective sub-bands of the two-dimensional spatial frequency domain;
storing said data sets for a field or frame of said video signal;
quantizing the stored data sets in accordance with respective values, said values being such that the amount of quantization of one of the data sets constituting a sub-band to which dc luminance information of the signal is at least predominantly confined is less than the average of the amounts of quantization of the remaining data sets;
writing the stored data to a quantizer, for carrying out said quantizing, in a desired sequence;
controlling said quantizing in accordance with said desired sequence such that each datum written to said quantizer is appropriately quantized;
entropy encoding the quantized data sets such that quantized data representative of dc luminance information is coded by a first coding technique and quantized data representative of ac luminance information is coded by a second coding technique;
and
controlling said entropy encoding in accordance with said desired sequence such that each quantized datum is subjected to the appropriate one of said first and second coding techniques.

5 more elements

Apparatus for compressing a video signal, the apparatus comprising:

a spatial two-dimensional sub-band filtering arrangement operative to filter a digital video signal to form a plurality of data sets constituting respective sub-bands of the two-dimensional spatial frequency domain;
a store for storing said data sets for a field or frame of said video signal;
a quantizer operative to quantize the stored data sets in accordance with respective values, said values being such that the amount of quantization of one of the data sets constituting a sub-band to which dc luminance information of the signal is at least predominantly confined is less than the average of the amounts of quantization of the remaining data sets;
an entropy encoder operative to encode the quantized data sets, said entropy encoder comprising a first coding portion for coding quantized data representative of dc luminance information and a second coding portion for coding quantized data representative of ac luminance information;
and
sequencing means operative to control writing of the stored data from said store to said quantizer in a desired sequence, to control the operation of said quantizer in accordance with said desired sequence such that each datum written thereto is appropriately quantized, and to control the operation of said entropy encoder in accordance with said desired sequence such that each quantized datum is directed to the appropriate one of said first and second coding portions.

3 more elements

Dependencies are inferred from the claim text.

Compression of video signals

Life of this patent

Compression of video signals

Life of this patent

Abstract

Claims42