# US 2014/0192869 A1 · Method, device, computer program, and information storage means for encoding or decoding a video sequence

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2014/0192869 A1
- Document ID: US20140192869A1
- Status: Published application
- Kind: A1
- Application number: 14/146,598
- Filed: 2014-01-02
- Published: 2014-07-10
- Earliest claimed: 2013-01-04
- Assignees: Canon Kabushiki Kaisha
- Applicants: Canon Kabushiki Kaisha
- Inventors: GUILLAUME LAROCHE; EDOUARD FRANÇOIS; CHRISTOPHE GISQUET; PATRICE ONNO
- Web page: https://patentgrep.com/patent/US20140192869A1

## CPC

- H04N 19/176: the region being a block, e.g. a macroblock
- H04N 19/117: Filters, e.g. for pre-processing or post-processing (sub-band filter banks H04N19/635)
- H04N 19/14: Coding unit complexity, e.g. amount of activity or edge presence estimation (H04N19/146 takes precedence)
- H04N 19/147: according to rate distortion criteria (rate-distortion as a criterion for motion estimation H04N19/567)
- H04N 19/19: using optimisation based on Lagrange multipliers
- H04N 19/82: involving filtering within a prediction loop
- H04N 19/86: involving reduction of coding artifacts, e.g. of blockiness
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

The invention relates to video coding. A method of encoding or decoding such a video sequence according to the invention comprises: obtaining a reconstructed frame area made of an array of sample values; applying a sample adaptive offset, SAO, filtering to the reconstructed frame area based on SAO parameters; wherein at least one of the SAO parameters is determined independently of the sample values of the reconstructed frame area. Preferably, the sample-independent SAO parameters define an Edge Offset filtering.

## Claims

### Claim 1

A method of encoding or decoding a video sequence, the method comprising decoding an encoded frame into a decoded frame, wherein decoding the encoded frame comprises:
obtaining a reconstructed frame area made of an array of sample values;
applying a sample adaptive offset, SAO, filtering to the reconstructed frame area based on SAO parameters;
wherein at least one of the SAO parameters is determined independently of the sample values of the reconstructed frame area.

### Claim 2 (depends on 1)

The method of claim 1, wherein the SAO parameters include a SAO filtering type, a SAO-type-depending parameter and offsets, wherein the at least one SAO parameter includes the offsets.

### Claim 3 (depends on 2)

The method of claim 2, wherein the offsets of the at least one SAO parameter includes four prefixed offsets equal to |1, 0, 0 −1|.

### Claim 4 (depends on 2)

The method of claim 2, wherein the offsets of the at least one SAO parameter includes four offsets O1, O2, O3, O4 such that O1>O2≧0≧O3>O4 and |O1=|O4| and |O2|=|O3|, where |x| is the absolute value of x; and the offsets depend on a quantization parameter used to decode a frame area of the encoded frame.

### Claim 5 (depends on 2)

The method of claim 2, wherein the at least one SAO parameter further includes the SAO filtering type.

### Claim 6 (depends on 5)

The method of claim 5, wherein the SAO filtering type determined independently of the sample values is set to Edge Offset filtering.

### Claim 7 (depends on 2)

The method of claim 2, wherein the at least one SAO parameter includes all the SAO parameters, including the SAO-type-depending parameter.

### Claim 8 (depends on 7)

The method of claim 7, wherein the SAO filtering type is a SAO Edge Offset filtering and the SAO-type-depending parameter is a direction of Edge Offset filtering.

### Claim 9 (depends on 8)

The method of claim 8, wherein the Edge Offset direction is prefixed for a plurality of frames of the video sequence.

### Claim 10 (depends on 9)

The method of claim 9, wherein the prefixed Edge Offset direction is a horizontal direction.

### Claim 11 (depends on 8)

The method of claim 8, wherein the Edge Offset direction is selected for each new frame within the video sequence, based on a picture order count associated with each new frame.

### Claim 12 (depends on 9)

The method of claim 9, wherein vertical and horizontal Edge Offset directions are favored for selection compared to diagonal Edge Offset directions.

### Claim 13 (depends on 12)

The method of claim 12, wherein the diagonal Edge Offset directions are disabled for selection.

### Claim 14 (depends on 8)

The method of claim 8, wherein the Edge Offset direction is perpendicular to an Edge Offset direction determined for a co-located frame area in another frame of the video sequence.

### Claim 15 (depends on 8)

The method of claim 8, wherein the Edge Offset direction is determined based on a direction for spatial prediction associated with the reconstructed frame area.

### Claim 16 (depends on 15)

The method of claim 15, wherein the Edge Offset direction is the closest direction to a perpendicular of the spatial prediction direction, from amongst predefined directions.

### Claim 17 (depends on 1)

The method of claim 1, wherein frames of the video sequence are encoded using temporal prediction according to a temporal prediction frame hierarchy between frames; and the SAO filtering is enabled for frame areas belonging to a frame having a lower depth according to the temporal prediction frame hierarchy, the SAO filtering is disabled for frame areas belonging to a frame having a higher depth according to the temporal prediction frame hierarchy, and enabling SAO filtering for frame areas belonging to a frame having a middle depth according to the temporal prediction frame hierarchy depends on quantization parameters associated with the depths or on Lagrange parameter λ.

### Claim 18 (depends on 1)

The method of claim 1, wherein SAO parameters are determined for another frame of the video sequence; and the SAO parameters to be used for SAO-filtering the reconstructed frame area are:
by-default SAO parameters if the SAO parameters determined for a co-located frame area in the other frame define no SAO filtering or a Band Offset filtering,
the same SAO parameters, except a perpendicular Edge Offset direction, as those determined for a co-located frame area in the other frame if those determined parameters define an Edge Offset filtering.

### Claim 19 (depends on 1)

The method of claim 1, further comprising cascading several SAO filterings on the reconstructed frame area based on respective sets of SAO parameters, wherein at least one SAO parameter of each respective set of SAO parameters is determined independently of the sample values of the reconstructed frame area.

### Claim 20 (depends on 19)

The method of claim 19, wherein three Edge Offset SAO filterings are cascaded corresponding to three Edge Offset directions that are different from an Edge Offset direction determined for a co-located frame area in another frame of the video sequence.

### Claim 21 (depends on 19)

The method of claim 19, wherein the bitstream comprises a plurality of flags to specify whether associated Edge Offset directions are enabled or not.

### Claim 22 (depends on 19)

The method of claim 19, wherein the direction of the SAO filtering first occurring in the cascade is determined based on an Edge Offset direction determined for a co-located frame area in another frame of the video sequence.

### Claim 23 (depends on 19)

The method of claim 19, wherein the several cascaded SAO filterings uses the same set of offsets.

### Claim 24

A device for encoding or decoding a video sequence, comprising an internal decoder configured to decode an encoded frame into a decoded frame, wherein the internal decoder comprises:
a frame area module configured to obtain a reconstructed frame area made of an array of sample values;
a sample adaptive offset, SAO, filter configured to apply a SAO filtering to the reconstructed frame area based on SAO parameters;
a SAO parameter determining module configure to determine at least one of the SAO parameters independently of the sample values of the reconstructed frame area.

### Claim 25 (depends on 24)

The device of claim 24, wherein the SAO parameters include a SAO filtering type, a SAO-type-depending parameter and offsets, wherein the at least one SAO parameter includes the offsets.

### Claim 26 (depends on 25)

The device of claim 25, wherein the offsets of the at least one SAO parameter includes four prefixed offsets equal to |1, 0, 0 −1|.

### Claim 27 (depends on 25)

The device of claim 25, wherein the at least one SAO parameter further includes the SAO filtering type.

### Claim 28 (depends on 25)

The device of claim 25, wherein the at least one SAO parameter includes all the SAO parameters, including the SAO-type-depending parameter.

### Claim 29 (depends on 28)

The device of claim 28, wherein the SAO filtering type is a SAO Edge Offset filtering and the SAO-type-depending parameter is a direction of Edge Offset filtering.

### Claim 30 (depends on 24)

The device of claim 24, wherein frames of the video sequence are encoded using temporal prediction according to a temporal prediction frame hierarchy between frames; and the device is configured to enable SAO filtering for frame areas belonging to a frame having a lower depth according to the temporal prediction frame hierarchy, to disable SAO filtering for frame areas belonging to a frame having a higher depth according to the temporal prediction frame hierarchy, and to enable SAO filtering for frame areas belonging to a frame having a middle depth according to the temporal prediction frame hierarchy depending on quantization parameters associated with the depths or on Lagrange parameter λ.

### Claim 31 (depends on 24)

The device of claim 24, wherein SAO parameters are determined for another frame of the video sequence; and the SAO parameters to be used for SAO-filtering the reconstructed frame area are:
by-default SAO parameters if the SAO parameters determined for a co-located frame area in the other frame define no SAO filtering or a Band Offset filtering,
the same SAO parameters, except a perpendicular Edge Offset direction, as those determined for a co-located frame area in the other frame if those determined parameters define an Edge Offset filtering.

### Claim 32 (depends on 24)

The device of claim 24, comprising several SAO filters in cascade to cascade several SAO filterings on the reconstructed frame area based on respective sets of SAO parameters, wherein at least one SAO parameter of each respective set of SAO parameters is determined independently of the sample values of the reconstructed frame area.

### Claim 33 (depends on 1)

A non-transitory computer-readable medium storing a program which, when executed by a microprocessor or computer system in a device, causes the device to perform the steps of any of claim 1.