Method and apparatus for encoding and decoding video signal using adaptive sampling

1. A method of performing an interpolation filtering on a video signal, comprising:

determining, by a filtering unit, an adaptive sampling rate based on information about properties of a decoded picture;

performing, by the filtering unit, a first interpolation filtering using samples positioned according to the adaptive sampling rate,

wherein the adaptive sampling rate corresponds to a variable sampling rate, and wherein the variable sampling rate indicates a non-equidistant sampling rate; and

performing, by the filtering unit, a second interpolation filtering using samples to which the first interpolation filtering has been performed, wherein the first and the second interpolation filtering are performed at different sampling rates, and a sampling rate of the second interpolation filtering is determined based on a rate conversion parameter which is used for converting a sampling rate.

2. The method of claim 1 , wherein if the adaptive sampling rate corresponds to a reduced sampling rate, the first interpolation filtering is, by the filtering unit, performed based on a uniformly reduced tap length over a filter support area.

3. The method of claim 1 , wherein the second interpolation filtering is, by the filtering unit, performed within a different filter support area using samples generated by the first interpolation filtering.

4. The method of claim 1 , wherein the adaptive sampling rate is, by the filtering unit, determined based on a rate conversion parameter.

5. The method of claim 4 , wherein the adaptive sampling rate is, by the filtering unit, determined based on a distance function according to a position of an interpolated sample.

6. The method of claim 1 , wherein the information about the properties of the decoded picture comprises at least one of a block size and a picture parameter.

7. The method of claim 6 , wherein the picture parameter is obtained from a coded bit stream or derived from the decoded picture.

8. An apparatus of performing an interpolation filtering on a video signal, comprising:

an adaptive sampling unit configured to determine an adaptive sampling rate based on property information of a decoded picture; and

an interpolation filter configured to

perform a first interpolation filtering using samples positioned according to the adaptive sampling rate,

wherein the adaptive sampling rate corresponds to a variable sampling rate, and wherein the variable sampling rate indicates a non-equidistant sampling rate, and

perform a second interpolation filtering using samples to which the first interpolation filtering has been performed, wherein the first and the second interpolation filtering are performed at different sampling rates, and a sampling rate of the second interpolation filtering is determined based on a rate conversion parameter which is used for converting a sampling rate.

9. The apparatus of claim 8 , wherein when the adaptive sampling rate corresponds to a reduced sampling rate, the first interpolation filtering is performed based on an uniformly reduced tap length over a filter support area.

10. The apparatus of claim 8 , wherein the interpolation filter is further configured to perform the second interpolation filtering within a different filter support area using samples generated by the first interpolation filtering.

11. The apparatus of claim 8 ,

wherein the adaptive sampling rate is determined based on a function of distance from an interpolated sample position.

12. The apparatus of claim 8 ,

wherein the property information of the decoded picture includes at least one of a block size and a picture parameter.

13. A non-transitory computer readable medium containing program instructions for causing a computer to perform the method of claim 1 .