EP-4738822-A1 - VIDEO ENCODING METHOD AND ELECTRONIC DEVICE

Abstract

A method of encoding a video is provided. The method may include: partitioning an image frame into a coding tree unit (CTU); deciding prediction mode candidates of the coding tree unit by applying first low complexity rate-distortion optimization (LC-RDO), wherein the first LC-RDO includes applying a first correction value for correcting at least one of a rate, distortion, or rate-distortion cost; deciding a prediction mode from among the prediction mode candidates by applying second LC-RDO, wherein the second LC-RDO includes applying a second correction value for correcting at least one of the rate, distortion, or rate-distortion cost; and generating a bitstream based on the decided prediction mode.

Inventors

• YOO, KIWON
• Kang, WooSeok
• KIM, DOOHYUN
• KIM, MINHO
• JI, Kumran
• CHOI, BUMKWI

Assignees

• Samsung Electronics Co., Ltd.

Dates

Publication Date

20260506

Application Date

20240807

Claims (15)

1. A method of encoding a video, the method comprising: partitioning an image frame into a coding tree unit (CTU); deciding prediction mode candidates of the coding tree unit by applying first low complexity rate-distortion optimization (LC-RDO), wherein the first LC-RDO includes applying a first correction value for correcting at least one of a rate, distortion, or rate-distortion cost; deciding a prediction mode from among the prediction mode candidates by applying second LC-RDO, wherein the second LC-RDO includes applying a second correction value for correcting at least one of the rate, distortion, or rate-distortion cost; and generating a bitstream based on the decided prediction mode.
2. The method of claim 1, wherein the first correction value and the second correction value are applied based on a pre-calculated lookup table.
3. The method of claim 2, wherein the pre-calculated lookup table is generated based on a difference between a rate-distortion cost of rate-distortion optimization (RDO) and a rate-distortion cost of low complexity rate-distortion optimization (LC-RDO), wherein the rate-distortion cost of the RDO is calculated by applying the RDO to an encoding process and the rate-distortion cost of the LC-RDO is calculated by applying the LC-RDO to the encoding process.
4. The method of any one of claims 1 to 3, wherein the first LC-RDO includes applying a first rate correction value for correcting a rate and a first distortion correction value for correcting distortion, and the second LC-RDO includes applying a second rate correction value for correcting the rate and a second distortion correction value for correcting the distortion.
5. The method of any one of claims 1 to 3, wherein the first LC-RDO includes applying a first rate-distortion cost correction value for correcting the rate-distortion cost, and the second LC-RDO includes applying a second rate-distortion cost correction value for correcting the rate-distortion cost.
6. The method of any one of claims 1 to 5, further comprising determining whether to partition the coding tree unit into a plurality of coding units, wherein a determination of whether to partition each of the coding units is recursively performed until an optimal prediction mode of each of the coding units is decided.
7. The method of claim 6, wherein the determining of whether to partition the coding tree unit into the plurality of coding units comprises determining whether to partition the coding tree unit by applying third LC-RDO, wherein the third LC-RDO includes applying a third correction value for correcting at least one of the rate, distortion, or rate-distortion cost.
8. An electronic device for encoding a video, the electronic device comprising: memory storing one or more instructions; and one or more processors configured to execute the one or more instructions stored in the memory, wherein the one or more processors are configured to execute the one or more instructions to partition an image frame into a coding tree unit (CTU), decide prediction mode candidates of the coding tree unit by applying first low complexity rate-distortion optimization (LC-RDO), wherein the first LC-RDO includes applying a first correction value for correcting at least one of a rate, distortion, or rate-distortion cost, decide a prediction mode from among the prediction mode candidates by applying second LC-RDO, wherein the second LC-RDO includes applying a second correction value for correcting at least one of the rate, distortion, or rate-distortion cost, and generate a bitstream based on the decided prediction mode.
9. The electronic device of claim 8, wherein the first correction value and the second correction value are applied based on a pre-calculated lookup table.
10. The electronic device of claim 9, wherein the pre-calculated look-up table is generated based on a difference between a rate-distortion cost of rate-distortion optimization (RDO) and a rate-distortion cost of low complexity rate-distortion optimization (LC-RDO), wherein the rate-distortion cost of the RDO is calculated by applying the RDO to an encoding process and the rate-distortion cost of the LC-RDO is calculated by applying the LC-RDO to the encoding process.
11. The electronic device of any one of claims 8 to 10, wherein the first LC-RDO includes applying a first rate correction value for correcting the rate and a first distortion correction value for correcting the distortion, and the second LC-RDO includes applying a second rate correction value for correcting the rate and a second distortion correction value for correcting the distortion.
12. The electronic device of any one of claims 8 to 10, wherein the first LC-RDO includes applying a first rate-distortion cost correction value for correcting the rate-distortion cost, and the second LC-RDO includes applying a second rate-distortion cost correction value for correcting the rate-distortion cost.
13. The electronic device of any one of claims 8 to 12, wherein the one or more processors are configured to execute the one or more instructions to determine whether to partition the coding tree unit into a plurality of coding units, wherein a determination of whether to partition each of the coding units is recursively performed until an optimal prediction mode of each of the coding units is decided.
14. The electronic device of claim 13, wherein the one or more processors are configured to execute the one or more instructions to determine whether to partition the coding tree unit by applying third LC-RDO, wherein the third LC-RDO includes applying a third correction value for correcting at least one of the rate, distortion, or rate-distortion cost.
15. A computer-readable recording medium storing a program for executing the method of any one of claims 1 to 7 on a computer.

Description

Technical Field The present disclosure relates to a video encoding method considering rate-distortion cost and an electronic device for encoding a video. Background Art Video codecs divide video frames into smaller units through block partitioning and process and compress the divided units. As a key technology for a compression process of video codecs, rate-distortion optimization (RDO) is used. The RDO selects an optimal compression method from among various encoding modes by considering the trade-off between the bit rate and distortion of compressed data. Meanwhile, high-performance video codecs require significant computational complexity to achieve high compression efficiency. However, in resource-constrained environments such as mobile devices, low computational complexity and power consumption become important considerations. Accordingly, low complexity rate-distortion optimization (LC-RDO) for efficient video data compression with low computational complexity is being used. Disclosure of Invention Solution to Problem According to an aspect of the present disclosure, a method of encoding a video may be provided. The method may include partitioning an image frame into a coding tree unit (CTU). The method may include deciding prediction mode candidates of the coding tree unit by applying first low complexity rate-distortion optimization (LC-RDO). The first LC-RDO may include applying a first correction value for correcting at least one of a rate, distortion, or rate-distortion cost. The method may include deciding a prediction mode from among the prediction mode candidates by applying second LC-RDO. The second LC-RDO may include applying a second correction value for correcting at least one of the rate, distortion, or rate-distortion cost. The method may include generating a bitstream based on the decided prediction mode. According to an aspect of the present disclosure, an electronic device for encoding a video may be provided. The electronic device may include memory storing one or more instructions; and one or more processors configured to execute the one or more instructions stored in the memory. The one or more processors may be configured to execute the one or more instructions to partition an image frame into a coding tree unit (CTU). The one or more processors may be configured to execute the one or more instructions to apply first low complexity rate-distortion optimization (LC-RDO) to decide prediction mode candidates of the coding tree unit. The first LC-RDO may include applying a first correction value for correcting at least one of a rate, distortion, or rate-distortion cost. The one or more processors may be configured to execute the one or more instructions to apply second LC-RDO to decide a prediction mode from among the prediction mode candidates. The second LC-RDO may include applying a second correction value for correcting at least one of the rate, distortion, or rate-distortion cost. The one or more processors may be configured to execute the one or more instructions to generate a bitstream based on the decided prediction mode. According to an aspect of the present disclosure, a computer-readable recording medium storing a program for executing any one of the above-described methods or methods to be described below, for encoding a video, performed by an electronic device, may be provided. Brief Description of Drawings FIG. 1 is a diagram illustrating an encoding process of an electronic device, according to an embodiment of the present disclosure.FIG. 2A is a diagram for describing a concept of an encoding unit according to an embodiment of the present disclosure.FIG. 2B is a diagram for describing a concept of an encoding unit according to an embodiment of the present disclosure.FIG. 2C is a diagram for describing a recursive search operation for determining a partitioning structure of a block in an electronic device, according to an embodiment of the present disclosure.FIG. 3 is a flowchart for describing an operation of encoding a video in an electronic device, according to an embodiment of the present disclosure.FIG. 4A is a block diagram for describing an operation of calculating rate-distortion (RD) cost in general rate-distortion optimization (RDO).FIG. 4B is a block diagram for describing an operation of calculating RD cost in general low complexity-rate-distortion optimization (LC-RDO).FIG. 5A is a block diagram for describing an RD cost calculation operation in LC-RDO used by an electronic device according to an embodiment of the present disclosure.FIG. 5B is a flowchart for describing an RD cost calculation operation in LC-RDO used by an electronic device, according to an embodiment of the present disclosure.FIG. 6A is a block diagram for describing an RD cost calculation operation in LC-RDO used by an electronic device, according to an embodiment of the present disclosure.FIG. 6B is a block diagram for describing an RD cost calculation operation in LC-LC-RDO used by an e