Translational and affine candidates in a unified list

1. A method for video decoding, comprising:

determining one or more prediction models respectively for one or more prediction candidates used for the video decoding based on one or more control point motion vectors of a current block of the video being decoded;

determining from the one or more control point motion vectors that a first prediction model of the one or more prediction models is to be a translational prediction model, wherein the first prediction model of a prediction candidate is a translational prediction model when a relative motion between two of the one or more control point motion vectors is less than or equal to a first value or higher than a second value depending on a height and a width of the current block;

determining from the one or more control point motion vectors that a second prediction model of the one or more prediction models is to be an affine prediction model; and

decoding the video based on a candidate list comprising the one or more prediction candidates determined respectively from the one or more prediction models.

2. The method of claim 1 , wherein the determining from the one or more control point motion vectors that a first prediction model of the one or more prediction models is to be a translational prediction model, is based on the one or more control motion vectors being in inter mode.

3. The method of claim 1 , wherein the second prediction model of the one or more prediction models is to be an affine prediction model when a relative motion between two of the one or more control point motion vectors is higher than the first value and lower than or equal to the second value depending on a height and a width of the current block.

4. The method of claim 1 , wherein the affine prediction model is a 4-parameter affine prediction model or a 6-parameter affine prediction model.

5. The method of claim 1 , wherein the one or more prediction models comprise an AMVP mode or a merge mode.

6. An apparatus for video decoding, comprising one or more processors, wherein the one or more processors are configured to:

determine one or more prediction models respectively for one or more prediction candidates used for the video decoding based on one or more control point motion vectors of a current block of the video being decoded;

determine from the one or more control point motion vectors that a first prediction model of the one or more prediction models is to be a translational prediction model, wherein the first prediction model of a prediction candidate is a translational prediction model when a relative motion between two of the one or more control point motion vectors is less than or equal to a first value or higher than a second value depending on a height and a width of the current block;

determine from the one or more control point motion vectors that a second prediction model of the one or more prediction models is to be an affine prediction model; and

decode the video based on a candidate list comprising the one or more prediction candidates determined respectively from the one or more prediction models.

7. The apparatus of claim 6 , wherein the determining from the one or more control point motion vectors that a first prediction model of the one or more prediction models is to be a translational prediction model, is based on the one or more control motion vectors being in inter mode.

8. The apparatus of claim 6 , wherein the second prediction model of the one or more prediction models is to be an affine prediction model when a relative motion between two of the one or more control point motion vectors is higher than the first value and lower than or equal to the second value depending on a height and a width of the current block.

9. The apparatus of claim 6 , wherein the affine prediction model is a 4-parameter affine prediction model or a 6-parameter affine prediction model.

10. The apparatus of claim 6 , wherein the one or more prediction models comprise an AMVP mode or a merge mode.

11. A method for video encoding, comprising:

determining one or more prediction models respectively for one or more prediction candidates used for the video encoding based on one or more control point motion vectors of a current block of the video being encoded;

determining from the one or more control point motion vectors that a first prediction model of the one or more prediction models is to be a translational prediction model, wherein the first prediction model of a prediction candidate is a translational prediction model when a relative motion between two of the one or more control point motion vectors is less than or equal to a first value or higher than a second value depending on a height and a width of the current block;

determining from the one or more control point motion vectors that a second prediction model of the one or more prediction models is to be an affine prediction model; and

encoding the video based on a candidate list comprising the one or more prediction candidates determined respectively from the one or more prediction models.

12. The method of claim 11 , wherein the determining from the one or more control point motion vectors that a first prediction model of the one or more prediction models is to be a translational prediction model, is based on the one or more control motion vectors being in inter mode.

13. The method of claim 11 , wherein the second prediction model of the one or more prediction models is to be an affine prediction model when a relative motion between two of the one or more control point motion vectors is higher than the first value and lower than or equal to the second value depending on a height and a width of the current block.

14. The method of claim 11 , wherein the affine prediction model is a 4-parameter affine prediction model or a 6-parameter affine prediction model.

15. The method of claim 11 , wherein the one or more prediction models comprise an AMVP mode or a merge mode.

16. An apparatus for video encoding, comprising one or more processors, wherein the one or more processors are configured to:

determine one or more prediction models respectively for one or more prediction candidates used for the video encoding based on one or more control point motion vectors of a current block of the video being encoded;

determine from the one or more control point motion vectors that a first prediction model of the one or more prediction models is to be a translational prediction model, wherein the first prediction model of a prediction candidate is a translational prediction model when a relative motion between two of the one or more control point motion vectors is less than or equal to a first value or higher than a second value depending on a height and a width of the current block;

determine from the one or more control point motion vectors that a second prediction model of the one or more prediction models is to be an affine prediction model; and

encode the video based on a candidate list comprising the one or more prediction candidates determined respectively from the one or more prediction models.

17. The apparatus of claim 16 , wherein the determining from the one or more control point motion vectors that a first prediction model of the one or more prediction models is to be a translational prediction model, is based on the one or more control motion vectors being in inter mode.

18. The apparatus of claim 16 , wherein the second prediction model of the one or more prediction models is to be an affine prediction model when a relative motion between two of the one or more control point motion vectors is higher than the first value and lower than or equal to the second value depending on a height and a width of the current block.

19. The apparatus of claim 16 , wherein the affine prediction model is a 4-parameter affine prediction model or a 6-parameter affine prediction model.

20. The apparatus of claim 16 , wherein the one or more prediction models comprise an AMVP mode or a merge mode.