US-12621455-B2 - Apparatus, a method and a computer program for video coding and decoding

Abstract

A method comprising: obtaining image blocks (702) comprising image samples (704, 706); performing one or more pre-processing operations for at least part of the image samples (704, 706) based on directional correlation in said samples (704, 706); and encoding the pre-processed image samples (704, 706) with video or image coding means.

Inventors

• Alireza Zare
• Alireza Aminlou
• Jani Lainema
• Ramin Ghaznavi Youvalari
• Pekka ASTOLA

Assignees

• NOKIA TECHNOLOGIES OY

Dates

Publication Date

20260505

Application Date

20221006

Priority Date

20211021

Claims (20)

1. 1 . An apparatus comprising: at least one processor; and at least one memory including computer program code; the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: obtain image blocks comprising image samples; perform one or more pre-processing operations for at least part of the image samples based on directional correlation in said image samples, wherein at least one of the one or more preprocessing operations is configured to reduce a number of image samples along a direction having a strong correlation of an image content; and encode the pre-processed image samples.
2. 2 . The apparatus according to claim 1 , wherein: at least one of said pre-processing operations comprises downsampling the image content in direction of a reference line.
3. 3 . The apparatus according to claim 1 , wherein: at least one of said pre-processing operations comprises a packing operation.
4. 4 . The apparatus according to claim 3 , wherein the apparatus upon execution is further caused to: pack horizontal and vertical reference lines content into a single picture by using one or more partitioning operations.
5. 5 . The apparatus according to claim 3 , wherein the apparatus upon execution is further caused to: pack horizontal or vertical reference lines in units of a stride size of N samples in a first direction; and place each of N sample units in the first direction or a second direction.
6. 6 . The apparatus according to claim 3 , wherein the apparatus upon execution is further caused to: perform a loop of sampling horizontal or vertical reference lines with a stride size of every N samples, wherein the loop is repeated for each of offset values 1 to N defining a first set of samples to be sampled.
7. 7 . The apparatus according to claim 1 , wherein the apparatus upon execution is further caused to: apply a one-dimensional (1-D) spatial-to frequency domain transform on the image samples in direction of the reference line.
8. 8 . The apparatus according to claim 2 , wherein the apparatus upon execution is further caused to: signal direction of the reference line by a picture-level indication.
9. 9 . The apparatus according to claim 2 , wherein: at least one of said pre-processing operations comprises switching off one or more coding tools.
10. 10 . The apparatus according to claim 2 , wherein the apparatus upon execution is further caused to: limit an intra sub-partitioning (ISP) to the direction of the reference line.
11. 11 . The apparatus according to claim 2 , wherein the apparatus upon execution is further caused to: ignore a maximum number of allowed sub-partitions, when an intra sub-partitioning (ISP) is carried out in the direction of the reference line.
12. 12 . The apparatus according to claim 1 , wherein the apparatus upon execution is further caused to: carry out intra prediction as one-dimensional (1-D) planar prediction.
13. 13 . The apparatus according to claim 1 , wherein: a filling order of a most probable mode (MPM) list is based on intra mode distribution in coding of reference lines content.
14. 14 . The apparatus according to claim 2 , wherein the apparatus upon execution is further caused to: alter a cross-component linear model (CCLM) mode according to the direction of the reference line.
15. 15 . A method comprising: obtaining image blocks comprising image samples, performing one or more pre-processing operations for at least part of the image samples based on directional correlation in said image samples, wherein at least one of said pre-processing operations is configured to reduce a number of image samples along a direction having a strong correlation of an image content; and encoding the pre-processed image samples.
16. 16 . The method according to claim 15 , wherein: at least one of said pre-processing operations comprises downsampling the image content in direction of a reference line.
17. 17 . The method according to claim 15 , wherein: at least one of said pre-processing operations comprises a packing operation.
18. 18 . The method according to claim 17 , comprising: packing horizontal and vertical reference lines content into a single picture using one or more partitioning operations.
19. 19 . The method according to claim 17 , comprising: packing the horizontal or the vertical reference lines in units of a stride size of N samples in a first direction; and placing each of N sample units in the first direction or a second direction.
20. 20 . The method according to claim 17 , further comprising: performing a loop of sampling the horizontal or the vertical reference lines with a stride size of every N samples, wherein the loop is repeated for each of offset values 1 to N defining a first set of samples to be sampled.

Description

RELATED APPLICATION This application was originally filed as PCT Application No. PCT/FI2022/050666, filed on Oct. 6, 2022, which claims priority from FI application No. 20216089, filed on Oct. 21, 2021, of which priority is claimed and is incorporated herein by reference in its entirety. TECHNICAL FIELD The present invention relates to an apparatus, a method and a computer program for video coding and decoding. BACKGROUND Massively Parallel Processing (MPP) may be defined as a storage structure or a processing structure designed to handle the coordinated processing of program operations by multiple processors. When the processing is aimed for coding of media content, a term Massively Parallel Coding (MPC) may be used. Parallel processing is a useful property for a video codec, which may enable the real-time operation and improve utilization of computational resources. The massively parallel coding (MPC) may be considered a necessity for real-time coding of emerging high-resolution content and large scale video streaming. Contemporary video codecs mainly support high-level parallelization using picture partitioning tools, such as partitioning into tiles, slices, subpictures, etc. This kind of high-level parallelization has a limited scalability, whereas a block/coding tree unit (CTU)-level massively parallel coding (MPC) of video content would provide much enhanced scalability. However, in a massively parallel video coding paradigm where CTUs are coded in parallel, reference samples from the adjacent reconstructed blocks are not available for reconstructing reference samples array in intra prediction, as the CTUs are coded independently. Thus, MPC may incur coding efficiency losses since the coding dependencies among the CTUs are prohibited. SUMMARY Now in order to at least alleviate the above problems, enhanced methods are introduced herein. Various aspects include a method, an apparatus and a non-transitory computer readable medium comprising a computer program, or a signal stored therein, which are characterized by what is stated in the independent claims. Various details of the embodiments are disclosed in the dependent claims and in the corresponding images and description. The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention. A method according to a first aspect comprises obtaining image blocks comprising image samples; performing one or more pre-processing operations for at least part of the image samples based on directional correlation in said samples; and encoding the pre-processed image samples with video or image coding means. An apparatus according to a second embodiment comprises: means for obtaining image blocks comprising image samples; means for performing one or more pre-processing operations for at least part of the image samples based on directional correlation in said samples; and means for encoding the pre-processed image samples with video or image coding means. According to an embodiment, at least one of said pre-processing operations is configured to reduce the number of samples along a direction having a strong correlation of image content. According to an embodiment, at least one of said pre-processing operations comprises downsampling the content in reference lines direction. According to an embodiment, at least one of said pre-processing operations comprises a packing operation. According to an embodiment, the apparatus comprises means for packing horizontal and vertical reference lines content into a single picture using one or more partitioning operations. According to an embodiment, the apparatus comprises means for packing the horizontal or the vertical reference lines in units of a stride size of N samples in a first direction; and means for placing each of the N sample units in the first direction or a second direction. According to an embodiment, the apparatus comprises means for performing a loop of sampling the horizontal or the vertical reference lines with a stride size of every N samples, wherein the loop is repeated for each of offset values 1 to N defining the first sample to be sampled. According to an embodiment, the apparatus comprises means for applying a one-dimensional (1-D) spatial-to frequency domain transform on the image samples in the reference line direction. According to an embodiment, the apparatus comprises means for signaling the reference line direction by a picture-level indication. According to an embodiment, at least one of said pre-processing operations comprises switching off one or more coding tools. According to an embodiment, the apparatus comprises means for limiting the intra sub-partitioning (ISP) to the reference line direction. According to an embodiment, the