WO2015089721A1

WO2015089721A1 - Improved advanced residual prediction in 3dvc

Info

Publication number: WO2015089721A1
Application number: PCT/CN2013/089639
Authority: WO
Inventors: Kai Zhang; Jicheng An; Jian-Liang Lin
Original assignee: Mediatek Singapore Pte. Ltd.
Priority date: 2013-12-17
Filing date: 2013-12-17
Publication date: 2015-06-25

Abstract

An adaptive disparity vector derivation (ADVD) method for advanced residual prediction (ARP) and an advanced temporal residual prediction (ATRP) method are proposed. In ADVD, three DV candidates can be chosen to provide more accurate pseudo residues. In ATRP, the concept of ARP is also applied to the disparity compensated prediction. In the combination of ADVD and ATRP, three MV candidates can be chosen in ATRP.

Description

IMPROVED ADVANCED RESIDUAL PREDICTION IN

3DVC

TECHNICAL FIELD

[0001] The invention relates generally to Three-Dimensional (3D) video processing. In particular, the presented invention relates to advanced residual prediction.

BACKGROUND

[0002] In the current 3D-HEVC, advanced residual prediction (ARP) was adopted to replace the simple inter- view residual prediction for its better coding efficiency. In ARP, the base view is considered as a mirror of the current view. A mirror block is located with an estimated disparity vector (DV) and a mirror reference block for the mirror block is located using the same motion vector (MV) as the current block. Pseudo residues are generated by subtracting the reconstructed samples in the mirror block and in the mirror reference block. Then pseudo residues are used to predict the real residues of the current block. Fig. 1 depicts a sketch of ARP. In ARP, a coding unit (CU) can decide to use the pseudo residual prediction or not. A flag is transmitted to signal the on/off control including the weighting factor for the pseudo residual prediction (ARP). The weighting factor could be 0 (ARP disabled), 1 (ARP enabled) or ½ (The ARP is enabled but the pseudo residues will be divided by 2). For each CU, the encoder determines to enable or disable the ARP according to the rate- distortion optimization (RDO) criterion, and signals the control flag in the bit-stream.

[0003] It plays a critical role to locate the mirror block in the base-view accurately since pseudo residues are similar to the real residues only if they are generated by similar samples. In ARP, the estimated DV is derived by a neighbouring block disparity vector ( BDV) procedure. The first encountered DV from a temporal or spatial neighbouring block is utilized by ARP as the estimated DV for the current block. Since such an estimated DV is not accurate enough, pseudo residual prediction may be inefficient in some cases. SUMMARY

[0004] In light of the previously described problems, an adaptive disparity vector derivation (ADVD) method for advanced residual prediction (ARP) and an advanced temporal residual prediction (ATRP) method are proposed. In ADVD, three DV candidates can be chosen to provide more accurate pseudo residues. In ATRP, the concept of ARP is also applied to the disparity compensated prediction. In the combination of ADVD and ATRP, three MV candidates can be chosen in ATRP.

[0005] Other aspects and features of the invention will become apparent to those with ordinary skill in the art upon review of the following descriptions of specific embodiments.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

[0006] Fig. 1 is a diagram illustrating a sketch of ARP, where PR represents pseudo residue;

[0007] Fig. 2 is a diagram illustrating the order to fill the DV candidate list;

[0008] Fig. 3 is a diagram illustrating the aligned temporal DV and the temporal DV;

[0009] Fig. 4 is a diagram illustrating the concept of the proposed ATRP;

[0010] Fig. 5 is a diagram illustrating the derivation of DMV;

[0011] Fig. 6 is a diagram illustrating the order to fill the MV candidate list in ATRP.

[0012] Fig. 7 is a diagram illustrating exemplary reference blocks.

DETAILED DESCRIPTION

[0013] The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.

[0014] An adaptive disparity vector derivation (ADVD) method is proposed to improve the ARP coding efficiency. In ADVD, three DV candidates are derived from temporal and spatial neighbouring blocks. The candidate list is filled according to the order depicted in Fig. 2. The aligned temporal DV is obtained from the aligned block, which is located by a scaled MV to the collocated picture, as depicted in Fig. 3. The aligned block can be obtained as follows. The left-top coordinate of the aligned block is equal to the left-top coordinate of a reference block inside or outside of the current block, added by the MV of the current block scaled to the collocated picture. Fig. 7 demonstrates exemplary reference blocks.

[0015] A new DV candidate is appended into the list only if it is not equal to any DV candidate already in the list.

[0016] In another embodiment, a new DV candidate is appended into the list only if it is not equal to the first DV candidate in the list.

[0017] In another embodiment, a new DV candidate is not appended into the list if it is equal to (0, 0).

[0018] In still another embodiment, a new DV candidate is not appended into the list if it is equal to (0, y), where y is equal to 0 or not.

[0019] If the list has not been fulfilled after checking DVs in spatial/temporal neighbouring blocks, the BDV or DoNBDV of the spatial/temporal neighbouring blocks are checked to fill the list. DoNBDV is used if DoNBDV is utilized in the NBDV derivation process. Otherwise, NBDV is used.

[0020] In one embodiment, the NBDV or DoNBDV of the left and above neighbouring blocks are checked to fill the list.

[0021] If the list has not been fulfilled after checking DVs and NBDV/DoNBDV in spatial/temporal neighbouring blocks, DoNBDV of the current block is checked to fill the list if DoNBDV is utilized in the NBDV derivation process.

[0022] If the list is empty after checking DVs and NBDV/DoNBDV in spatial/temporal neighbouring blocks, and DoNBDV of the current block, a default DV is inserted into the list as the first entry.

[0023] In one embodiment, the default DV is (0, 0).

[0024] If the list has not been fulfilled, default DVs are inserted into the list sequentially. [0025] In one embodiment, two default DVs are ( DVentry[0].x+4, DVentry[0].y), and ( DVentry[0].x-4, DVentry[0].y), where DVentry[0] is the first entry in the list.

[0026] An encoder can determine the best DV candidate used in ARP according to the RDO criterion, and signal the index to the decoder.

[0027] An advanced temporal residual prediction (ATRP) method is proposed for the disparity compensated prediction. In ATRP, the disparity parameters of the current PU are applied to the corresponding block in a temporal reference picture in the same view to generate the reference residual in temporal direction. The corresponding block in the temporal reference picture is located by a derived motion vector (DMV). DMV is the motion vector (MV) of the reference block which the current DV is pointing to in the reference view. The reference block can be obtained as follows. The left-top coordinate of the reference block is equal to the left-top coordinate of a reference block inside or outside of the current block, added by the DV of the current block. Fig. 7 demonstrates exemplary reference blocks. The concept of proposed ATRP is illustrated in Fig. 4, and the derivation of DMV is illustrated in Fig. 5.

[0028] When ADVD and ATRP are combined, three MV candidates are derived for ATRP. The order to fill the three MV candidates is depicted in Fig. 6. The spatial MVs and temporal MVs are derived from the spatial and temporal merging candidate list and the first two available spatial and/or temporal MVs will be included into the MV candidate list after the DMV.

[0029] In another embodiment, the first three available DMV and spatial and/or temporal MVs will be included into the MV candidate list.

[0030] A new MV candidate is appended into the list only if it is not equal to any MV candidate already in the list.

[0031] In another embodiment, a new MV candidate is appended into the list only if it is not equal to the first MV candidate in the list.

[0032] In still another embodiment, a new MV candidate is not appended into the list if it is equal to (0, 0).

[0033] If the list is empty after checking DMV and MVs in spatial/temporal neighbouring blocks, a default MV is inserted into the list as the first entry.

[0034] In one embodiment, the default MV is (0, 0).

[0035] If the list has not been fulfilled, default MVs are inserted into the list sequentially.

[0036] In one embodiment, two default MVs are ( MVentry[0].x+4, MVentry [0].y), and ( MVentry[0].x-4, MVentry [0].y). where MVentry [0] is the first entry in the list.

[0037] An encoder can determine the best MV candidate used in ATRP according to RDO criterion, and signal the index to the decoder, similar to what is done in ADVD for ARP.

Claims

1. A method of generating a derived disparity vector (DV), wherein the derived DV of a block is selected from multiple DV candidates.

2. The method as claimed in claim 1, wherein a new DV candidate is appended into the list only if it is not equal to any DV candidate already in the list.

3. The method as claimed in claim 1, wherein a new DV candidate is appended into the list only if it is not equal to the first DV candidate in the list.

4. The method as claimed in claim 1, wherein a new DV candidate is not appended into the list if it is equal to (0, 0).

5. The method as claimed in claim 1, wherein a new DV candidate not is appended into the list if it is equal to (0, y), where y is equal to 0 or not.

6. The method as claimed in claim 1, wherein the NBDV or DoNBDV of the spatial/temporal neighbouring blocks are checked to fill the list if the list has not been fulfilled after checking DVs in spatial/temporal neighbouring blocks. DoNBDV is used if DoNBDV is utilized in the NBDV derivation process. Otherwise, NBDV is used.

7. The method as claimed in claim 6, wherein the NBDV or DoNBDV of the left and above neighbouring blocks are checked to fill the list.

8. The method as claimed in claim 1, wherein DoNBDV of the current block is checked to fill the list if the list has not been fulfilled after checking DVs and

NBDV/DoNBDV in spatial/temporal neighbouring blocks, and DoNBDV is utilized in the NBDV derivation process.

9. The method as claimed in claim 1, wherein a default DV is inserted into the list as the first entry if the list is empty after checking DVs and NBDV/DoNBDV in spatial/temporal neighbouring blocks, and DoNBDV of the current block.

10. The method as claimed in claim 9, wherein the default DV is (0, 0).

11. The method as claimed in claim 1, wherein default DVs are inserted into the list sequentially if the list has not been fulfilled.

12. The method as claimed in claim 11, wherein two default DVs are (DVentry[0].x+4, DVentry[0].y), and ( DVentry[0].x-4, DVentry[0].y), where

DVentry[0] is the first entry in the list.

13. A method of generating a derived MV, wherein the derived MV of a block can be chosen from several candidate MVs.

14. The method as claimed in claim 13, wherein the first three available DMV and spatial and/or temporal MVs will be included into the MV candidate list.

15. The method as claimed in claim 13, wherein a new MV candidate is appended into the list only if it is not equal to any MV candidate already in the list.

16. The method as claimed in claim 13, wherein a new MV candidate is appended into the list only if it is not equal to the first MV candidate in the list.

17. The method as claimed in claim 13, wherein a new MV candidate is not appended into the list if it is equal to (0, 0).

18. The method as claimed in claim 13, wherein a default MV is inserted into the list as the first entry if the list is empty after checking DMV and MVs in spatial/temporal neighbouring blocks.

19. The method as claimed in claim 18, wherein the default MV is (0, 0).

20. The method as claimed in claim 13, wherein default MVs are inserted into the list sequentially if the list has not been fulfilled.

21. The method as claimed in claim 20, wherein two default MVs are (MVentry[0].x+4, MVentry[0].y), and ( MVentry[0].x-4, MVentry[0].y), where MVentry[0] is the first entry in the list.