Coding dynamic filters
AssigneeNokia Corporation
InventorJani Lainema
Life of this patent
Estimating the term…
Abstract
A video coding system for coding a video sequence comprising a sequence of video frames each having an array of pixel values, wherein an interpolation filter is defined in order to reconstruct the pixel values in the decoding process. The system codes coefficients of an interpolation filter differentially with respect to a predefined base filter in order to provide a set of difference values. As the base filter coefficients are known to both encoder and decoder and can be statistically reasonably close to the actual filters used in the video sequence, the decoder can reconstruct the pixel values based on the set of difference values.
Claims21
A method of encoding images in a digital video sequence for providing encoded video data, wherein the digital video sequence comprises a sequence of video frames, each frame having a plurality of pixel values, and wherein an interpolation filter having a plurality of coefficients represented by a plurality of coefficient values is used for reconstructing the pixel values in a frame of said digital video sequence from the encoded video data, said method characterized by
- coding the coefficient values of the interpolation filter differentially with respect to a predefined base filter to form a set of difference values, and
- adapting said set of difference values in the encoded video data so that the reconstruction of the pixel values is based on said set of difference values.
A video encoder comprising:
- means for encoding images in a digital video sequence having a sequence of video frames for providing encoded video data indicative of the video sequence, each frame of the video sequence comprising a plurality of pixel values, and
- means for defining an interpolation filter for reconstructing the pixel values in a frame of said digital video sequence in a decoding process, wherein the interpolation filter has a number of coefficients represented by a plurality of coefficient values, said video encoder characterized by
- means, responsive to the interpolation filter, for computing a difference between the coefficient values of said interpolation filter and a predefined base filter for providing a set of difference values, and
- means for adapting said set of difference values in the encoded video data so that the reconstruction of the pixel values in the decoding process is based on said set of difference values.
A method of decoding video data indicative of a digital video sequence comprising a sequence of video frames, each frame of the video sequence comprising a plurality of pixel values, wherein an interpolation filter having a plurality of coefficients represented by a plurality of coefficient values is used for reconstructing the pixel values in a frame of said digital video sequence, said method characterized by
- retrieving from the video data a set of difference values, said set of difference values indicative of a difference between the coefficient values of the interpolation filter and a predefined base filter;
- constructing a further filter based on said set of difference values and the predefined base filter;
- and
- reconstructing of the pixel values based on the further filter.
A video decoder comprising
- means for receiving video data in a bit-stream, the received video data indicative of a digital video sequence comprising a sequence of video frames, each frame of the video sequence comprising a plurality of pixel values, said video decoder characterized by
- means for retrieving a set of difference values from the bit-stream;
- means for constructing an interpolation filter based on a predefined base filter and said set of difference values;
- and
- means for reconstructing the pixel values in a frame of the video sequence based on the interpolation filter and the received video data.
A video coding system comprising:
- an encoder for encoding images in a digital video sequence having a sequence of video frames for providing encoded video data in a bit-stream indicative of the video sequence, each frame of the video sequence comprising a plurality of pixel values, the encoder having means for defining an interpolation filter for reconstructing the pixel values in a frame of said digital video sequence in a decoding process, wherein the interpolation filter has a plurality of filter coefficients represented by a plurality of coefficients values, and
- a decoder for receiving the encoded video data in the bit-stream for reconstructing the pixel values in a frame of the video sequence in the decoding process, said video coding system characterized in that
- the encoder further comprises:
- means for computing a difference between to the interpolation filter and a predefined base filter for providing a set of difference values, and
- means for adapting said set of difference values in the bit-stream;
- and that the decoding comprises:
- means for retrieving from the bit-stream said set of difference values;
- and
- means for constructing a further filter based on the predefined base filter and the retrieved set of difference values so that the reconstruction of the pixel values in the decoding process is based on the further filter.
Dependencies are inferred from the claim text.