# US 12,225,234 B2 · DPB size based reference picture entry constraints

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- Number: US 12,225,234 B2
- Document ID: US12225234B2
- Status: Granted
- Kind: B2
- Application number: 17/714,008
- Filed: 2022-04-05
- Published: 2022-07-28
- Granted: 2025-02-11
- Earliest claimed: 2019-10-07
- Assignees: Huawei Technologies Co., Ltd.
- Applicants: Huawei Technologies Co., Ltd.
- Inventors: Ye-Kui Wang
- Web page: https://patentgrep.com/patent/US12225234B2

## CPC

- H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards
- 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
- H04N 19/136: Incoming video signal characteristics or properties
- H04N 19/159: Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
- H04N 19/172: the region being a picture, frame or field
- H04N 19/174: the region being a slice, e.g. a line of blocks or a group of blocks
- H04N 19/187: the unit being a scalable video layer
- H04N 19/188: {the unit being a video data packet, e.g. a network abstraction layer [NAL] unit}
- H04N 19/30: using hierarchical techniques, e.g. scalability (H04N19/63 takes precedence)
- H04N 19/423: characterised by memory arrangements (H04N19/433 takes precedence)
- H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence)
- H04N 19/463: by compressing encoding parameters before transmission
- H04N 19/50: using predictive coding (H04N19/61 takes precedence)
- H04N 19/573: Motion compensation with multiple frame prediction using two or more reference frames in a given prediction direction
- H04N 19/593: involving spatial prediction techniques
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A video coding mechanism is disclosed. The mechanism includes receiving a bitstream comprising a current picture and a reference picture list syntax structure (ref_pic_list_struct( )) comprising a number of reference entries (num_ref_entries) constrained to a range of zero to a maximum decoded picture buffer size plus an offset. The current picture is decoded based on the ref_pic_list_struct( ) to produce a decoded picture. The decoded picture is forwarded for display as part of a decoded video sequence.

## Claims

### Claim 1

A method implemented by a decoder, the method comprising:
receiving a bitstream comprising a current picture, a decoded picture buffer parameter syntax structure (dpb_parameters( )), and a reference picture list syntax structure (ref_pic_list_struct( )) comprising a number of reference entries (num_ref_entries) constrained to a range of zero to a maximum decoded picture buffer size plus an offset, wherein the num_ref_entries specifies a number of entries in the ref_pic_list_struct( ), wherein the dpb_parameters( ) comprises a maximum decoded picture buffer minus one (max_dec_pic_buffering_minus1) that corresponds to the maximum decoded picture buffer size, wherein when the dpb_parameters( ) is included in a video parameter set (VPS), output layer sets (OLSs) to which the dpb_parameters( ) applies are specified by the VPS, and wherein when the dpb_parameters( ) is included in a sequence parameter set (SPS), OLSs to which the dpb_parameters( ) applies are specified by the SPS; and
decoding the current picture based on the ref_pic_list_struct( ) and dpb_parameters( ) to produce a decoded picture.

### Claim 2 (depends on 1)

The method of claim 1, wherein the reference picture list syntax structure is referenced according to a list index (listIdx) and a reference picture list structure index (rplsIdx), denoted as ref_pic_list_struct(listIdx, rplsIdx), wherein the number of reference entries is denoted num_ref_entries [listIdx][rplsIdx], and wherein the num_ref_entries [listIdx][rplsIdx] specifies a number of entries in the ref_pic_list_struct(listIdx, rplsIdx).

### Claim 3 (depends on 1)

The method of claim 1, wherein a number of pictures in a set of reference pictures (setOfRefPics) referred to in the reference picture list syntax structure is constrained to be less than or equal to the maximum decoded picture buffer size minus one.

### Claim 4 (depends on 3)

The method of claim 3, wherein the reference picture list syntax structure includes a reference picture list zero (RefPicList[0]) and a reference picture list one (RefPicList[1]), and wherein the set of reference pictures is a set of unique pictures referred to by all entries in RefPicList[0] that have a same network abstraction layer (NAL) unit header layer identifier (nuh_layer_id) as the current picture and all entries of in RefPicList[1] that have the same nuh_layer_id as the current picture.

### Claim 5 (depends on 3)

The method of claim 3, wherein the set of reference pictures is a same set for all slices of each picture.

### Claim 6 (depends on 1)

The method of claim 1, wherein the reference picture list syntax structure (ref_pic_list_struct( )) is present in a sequence parameter set (SPS), a picture header (PH) syntax structure, or a slice header.

### Claim 7

A method implemented by an encoder, the method comprising:
encoding a current picture based on a reference picture into a bitstream;
encoding a decoded picture buffer parameter syntax structure (dpb_parameters( )) into the bitstream;
encoding a reference picture list syntax structure (ref_pic_list_struct( )) into the bitstream, wherein the reference picture list syntax structure indicates the reference picture and comprises a number of reference entries (num_ref_entries), and wherein the number of reference entries are constrained to a range of zero to a maximum decoded picture buffer size plus an offset, wherein the num_ref_entries specifies a number of entries in the ref_pic_list_struct( ), wherein the dpb_parameters( ) comprises a maximum decoded picture buffer minus one (max_dec_pic_buffering_minus1) that corresponds to the maximum decoded picture buffer size, wherein when the dpb_parameters( ) is included in a video parameter set (VPS), output layer sets (OLSs) to which the dpb_parameters( ) applies are specified by the VPS, and wherein when the dpb_parameters( ) is included in a sequence parameter set (SPS), OLSs to which the dpb_parameters( ) applies are specified by the SPS; and
storing the bitstream for communication toward a decoder.

### Claim 8 (depends on 7)

The method of claim 7, wherein the reference picture list syntax structure is referenced according to a list index (listIdx) and a reference picture list structure index (rplsIdx), denoted as ref_pic_list_struct(listIdx, rplsIdx), wherein the number of reference entries is denoted num_ref_entries [listIdx][rplsIdx], and wherein the num_ref_entries [listIdx][rplsIdx] specifies a number of entries in the ref_pic_list_struct(listIdx, rplsIdx).

### Claim 9 (depends on 7)

The method of claim 7, wherein a number of pictures in a set of reference pictures (setOfRefPics) referred to in the reference picture list syntax structure is constrained to be less than or equal to the maximum decoded picture buffer size minus one.

### Claim 10 (depends on 9)

The method of claim 9, wherein the reference picture list syntax structure includes a reference picture list zero (RefPicList[0]) and a reference picture list one (RefPicList[1]), and wherein the set of reference pictures is a set of unique pictures referred to by all entries in RefPicList[0] that have a same network abstraction layer (NAL) unit header layer identifier (nuh_layer_id) as the current picture and all entries of in RefPicList[1] that have the same nuh_layer_id as the current picture.

### Claim 11 (depends on 9)

The method of claim 9, wherein the set of reference pictures is a same set for all slices of each picture.

### Claim 12

A video coding device comprising:
a memory storing instructions;
one or more processors coupled to the memory, the one or more processors configured to execute the instructions to cause the video decoding device to:
receive a bitstream comprising a current picture, a decoded picture buffer parameter syntax structure (dpb_parameters( )), and a reference picture list syntax structure (ref_pic_list_struct( )) comprising a number of reference entries (num_ref_entries) constrained to a range of zero to a maximum decoded picture buffer size plus an offset, wherein the num_ref_entries specifies a number of entries in the ref_pic_list_struct( ), wherein the dpb_parameters( ) comprises a maximum decoded picture buffer minus one (max_dec_pic_buffering_minus1) that corresponds to the maximum decoded picture buffer size, wherein when the dpb_parameters( ) is included in a video parameter set (VPS), output layer sets (OLSs) to which the dpb_parameters( ) applies are specified by the VPS, and wherein when the dpb_parameters( ) is included in a sequence parameter set (SPS), OLSs to which the dpb_parameters( ) applies are specified by the SPS; and
decode the current picture based on the ref_pic_list_struct( ) and dpb_parameters( ) to produce a decoded picture.

### Claim 13 (depends on 12)

The video coding device of claim 12, wherein the reference picture list syntax structure is referenced according to a list index (listIdx) and a reference picture list structure index (rplsIdx), denoted as ref_pic_list_struct(listIdx, rplsIdx), wherein the number of reference entries is denoted num_ref_entries [listIdx][rplsIdx], and wherein the num_ref_entries [listIdx][rplsIdx] specifies a number of entries in the ref_pic_list_struct(listIdx, rplsIdx).

### Claim 14 (depends on 12)

The video coding device of claim 12, wherein a number of pictures in a set of reference pictures (setOfRefPics) referred to in the reference picture list syntax structure is constrained to be less than or equal to the maximum decoded picture buffer size minus one.

### Claim 15 (depends on 14)

The video coding device of claim 14, wherein the reference picture list syntax structure includes a reference picture list zero (RefPicList[0]) and a reference picture list one (RefPicList[1]), and wherein the set of reference pictures is a set of unique pictures referred to by all entries in RefPicList[0] that have a same network abstraction layer (NAL) unit header layer identifier (nuh_layer_id) as the current picture and all entries in the RefPicList[1] that have the same nuh_layer_id as the current picture.

### Claim 16 (depends on 14)

The video coding device of claim 14, wherein the set of reference pictures is a same set for all slices of each picture.