Method and Apparatus for Using a Current Picture as a Reference Picture

• US 20180139461A1
• Filed: 05/26/2016
• Published: 05/17/2018
• Est. Priority Date: 05/28/2015
• Status: Active Grant

• Current Assignee: HFI Innovation, Inc. (MediaTek, Inc.)
• Original Assignee: HFI Innovation, Inc. (MediaTek, Inc.)
• Inventors: LIU, Shan, XU, Xiaozhong, LIU, Chenghao
• Granted Patent: US 10,045,038 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 1/66 for reducing bandwidth of signals; for improving efficiency of transmission H04B1/68 takes precedence
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/159 Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/174 the region being a slice, e.g. a line of blocks or a group of blocks
• CPC Class Codes: H04N 19/433 characterised by techniques for memory access
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/573 Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 19/82 involving filtering within a prediction loop

Abstract

Methods and apparatus of managing decoded picture buffer for a video coding system are disclosed for a system using an Inter prediction mode and an Intra Block Copy mode. According to one method, a current-picture-usage flag in a picture or slice level is determined. If the current-picture-usage flag indicates that the current picture is not allowed to be used as the reference picture for the current picture, only one picture buffer is allocated in a DPB (decoded picture buffer) for the current picture and a reconstructed current picture after in-loop filtering is stored in the picture buffer in the DPB. According to another method, the system allocates only one picture buffer in the DPB for both the Inter prediction mode and the Intra Block Copy mode of the current picture if all of one or more in-loop filters are disabled for the entire part of the current picture.

Claims

1. A method of managing a DPB (decoded picture buffer) for a video coding system, wherein the video coding system uses coding modes including an Inter prediction mode and an Intra Block Copy (IntraBC) mode, comprising:

determining a current-picture-usage flag in a picture level or slice level, wherein the current-picture-usage flag indicates whether the IntraBC mode is enabled for a current picture and the current picture is allowed to be used as a reference picture for the current picture;

if the current-picture-usage flag indicates that the IntraBC mode is not enabled and the current picture is not allowed to be used as the reference picture for the current picture;

allocating only one picture buffer in the DPB (decoded picture buffer) for the current picture; and

storing a reconstructed current picture after in-loop filtering or the reconstructed current picture before the in-loop filtering in said one picture buffer in the DPB; and

if the current-picture-usage flag indicates that the IntraBC mode is enabled for the current picture and the current picture is allowed to be used as the reference picture for the current picture;

allowing to allocate up to two picture buffers in the DPB for the current picture; and

allowing to store both the reconstructed current picture after the in-loop filtering and the reconstructed current picture before the in-loop filtering in said up to two picture buffers in the DPB.

2. The method of claim 1, wherein the current-picture-usage flag in the picture level or slice level is used to replace a corresponding current-picture-usage flag in a sequence level.

3. The method of claim 1, wherein the current-picture-usage flag in the picture level is used in addition to a corresponding current-picture-usage flag in a sequence level.

4. The method of claim 1, wherein the current-picture-usage flag in the slice level is used in addition to a corresponding current-picture-usage flag in a sequence level.

5. A method of managing a DPB (decoded picture buffer) for a video coding system, wherein the video coding system uses coding modes including an Inter prediction mode and an Intra Block Copy (IntraBC) mode, comprising:

determining whether one or more in-loop filters are used for an entire part of a current picture; and

if all of said one or more in-loop filters are disabled for the entire part of the current picture;

allocating only one picture buffer in the DPB (decoded picture buffer) for both the Inter prediction mode and the Intra Block Copy (IntraBC) mode of the current picture; and

storing only an unfiltered version of a reconstructed current picture in said one picture buffer.

6. The method of claim 5, further comprising:

determining a current-picture-usage flag in a sequence level, picture level or slice level, wherein the current-picture-usage flag indicates whether the IntraBC mode is enabled for the current picture and the current picture is allowed to be used as a reference picture for the current picture; and

if the current-picture-usage flag indicates that the IntraBC mode is not enabled and the current picture is not allowed to be used as the reference picture for the current picture, allocating only one picture buffer in the DPB for the Inter prediction mode of the current picture and storing only a filtered version of the reconstructed current picture in said one picture buffer.

7. The method of claim 5, wherein said one or more in-loop filters comprise deblocking filter and SAO filter (sample adaptive offset filter).

8. The method of claim 7, wherein the SAO filter is disabled if any of following conditions is true:

a) a sequence level SAO enable flag is false;

b) the sequence level SAO enable flag is true, there is only one slice in the current picture, and a slice level SAO flag is false for all colour components; and

c) the sequence level SAO enable flag is true, there are more than one slice in the current picture, and the slice level SAO flag is false for all colour components and for all slices.

9. The method of claim 7, wherein the deblocking filter is disabled if any of following conditions is true:

a) there is only one slice in the current picture, and a slice-level deblocking-filter-disable flag is present and is true;

b) there is only one slice in the current picture, the slice-level deblocking-filter-disable flag is not present, and a picture-level deblocking-filter-disable flag is true; and

c) there are more than one slice in the current picture, the slice-level deblocking-filter-disable flag is true for all slices when present or when not present, the picture-level deblocking-filter-disable flag is true.

10. An apparatus for managing a DPB (decoded picture buffer) for a video coding system, wherein the video coding system uses coding modes including an Inter prediction mode and an Intra Block Copy (IntraBC) mode, comprising one or more electronic circuits arranged to:

determine a current-picture-usage flag in a picture level or slice level, wherein the current-picture-usage flag indicates whether the IntraBC mode is enabled for a current picture and the current picture is allowed to be used as a reference picture for the current picture;

if the current-picture-usage flag indicates that the IntraBC mode is not enabled and the current picture is not allowed to be used as the reference picture for the current picture;

allocate only one picture buffer in the DPB (decoded picture buffer) for the current picture; and

store a reconstructed current picture after in-loop filtering or the reconstructed current picture before the in-loop filtering in said one picture buffer in the DPB; and

if the current-picture-usage flag indicates that the IntraBC mode is enabled for the current picture and the current picture is allowed to be used as the reference picture for the current picture;

allow to allocate up to two picture buffers in the DPB for the current picture; and

allow to store the reconstructed current picture after the in-loop filtering and the reconstructed current picture before the in-loop filtering in said up to two picture buffers in the DPB.

11. An apparatus for managing a DPB (decoded picture buffer) for a video coding system, wherein the video coding system uses coding modes including an Inter prediction mode and an Intra Block Copy (IntraBC) mode, comprising one or more electronic circuits arranged to:

determine whether one or more in-loop filters are used for an entire part of a current picture; and

if all of said one or more in-loop filters are disabled for the entire part of the current picture;

allocate only one picture buffer in the DPB (decoded picture buffer) for both the Inter prediction mode and the Intra Block Copy (IntraBC) mode of the current picture; and

store only an unfiltered version of a reconstructed current picture in said one picture buffer.