Encoding circuit for transform coding of a picture signal and decoding circuit for decoding said signal
An encoding circuit transforms a picture signal into blocks of, for example, 8*8 coefficients, in which each block of coefficients is read motion- adaptively. In the case of motion within a sub-picture, the block of coefficients is read in such an order that the obtained series of coefficients includes, as it were, two interleaved sub-series. The first series starts with a dc component. In a first embodiment, the second series starts with the most relevant motion coefficient. In a second embodiment, two interlaced sub-fields are separately transformed and the second series also starts with a dc coefficient. As a result, the coefficients are transmitted as much as possible in their order of significance. This particularly produces the largest possible clusters of zero value coefficients. Such clusters are transmitted as one compact run-length code so that an effective bit rate reduction is achieved, also for moving pictures.
1. An encoding circuit for transform coding pictures of an interlaced video signal, said encoding circuit comprising;
(a) means for partitioning each of said pictures into a plurality of interlaced sub-pictures;
(b) a transform circuit for transforming each of said sub-pictures into a two-dimensional coefficient block of coefficients;
(c) a motion detector for receiving each of said sub-pictures and for generating a motion signal when noticeable motion has been detected within a received sub-picture; and
(d) scanning means for reading said coefficients of said block in accordance with a predetermined scanning pattern depending on the motion signal, and for converting contiguous coefficients into a sequence of coefficients,
wherein, in response to said motion signal indicating no noticeable motion has been detected within a sub-picture, said scanning means provides each read coefficient contiguous to a previously read coefficient, and in response to said motion signal indicating noticeable motion has been detected within a sub-picture, said scanning means provides at least one jump to a predetermined coefficient of said block which is not contiguous to a previously read coefficient.
2. The encoding circuit as claimed in claim 1 , wherein said predetermined coefficient is representative of the presence of motion in said sub-picture.
3. The encoding circuit as claimed in claim 2 , wherein said predetermined coefficient is a coefficient representing a high vertical frequency and a low horizontal frequency.
4. An encoding circuit for transform coding pictures of an interlaced video signal, said encoding circuit comprising:
(a) means for partitioning each of said pictures into a plurality of interlaced sub-pictures;
(b) a transform circuit for transforming each of said sub-pictures into a two-dimensional coefficient block of coefficients;
(c) a motion detector for receiving each of said sub-pictures and for generating a motion signal when noticeable motion has been detected within a received sub-picture; and
(d) scanning means for reading said coefficients of said block in accordance with a predetermined scanning pattern depending on the motion signal, and for converting contiguous coefficients into a sequence of coefficients,
wherein, in response to said motion signal indicating no noticeable motion, has been detected within a sub-picture, said scanning means provides each read coefficient contiguous to a previously read coefficient, and in response to said motion signal indicating noticeable motion has been detected within a sub-picture, said scanning means provides at least one jump to a predetermined coefficient of said block which is not contiguous to a previously read coefficient,
wherein, in response to said motion signal indicating noticeable motion having been detected within a sub-picture, said scanning means reads the coefficients of the block following the pattern depicted in FIG. 7 of the drawings.
5. A decoding circuit for decoding a transformed interlaced video signal, the video signal being partitioned into interlaced sub-pictures, each of said sub-pictures being transformed into a block of coefficients and converted into a sequence of coefficients, a motion signal being associated with each block to indicate whether noticeable motion has been detected within a sub-picture, the decoding circuit comprising:
(a) means for receiving said sequences of coefficients and motion signals;
(b) storage means for storing each sequence of coefficients in a block of coefficients in accordance with a predetermined storage pattern depending on the motion signal; and
(c) an inverse transform circuit for transforming each block of coefficients into respective sub-pictures collectively constituting a picture of the video signal,
wherein, in response to said motion signal indicating no noticeable motion has been detected within the sub-picture, said storage means provides each stored coefficient contiguous to a previously stored coefficient, and in response to said motion signal indicating noticeable motion has been detected within a sub-picture. said storage means provides at least one jump to a predetermined coefficient of said block which is not contiguous to a previously stored coefficient.