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EP-4101168-B1 - SIMPLIFYING SIGNALLING SLICE HEADER SYNTAX ELEMENTS

EP4101168B1EP 4101168 B1EP4101168 B1EP 4101168B1EP-4101168-B1

Inventors

  • ESENLIK, SEMIH
  • WANG, BIAO
  • KOTRA, ANAND MEHER
  • ALSHINA, Elena Alexandrovna

Dates

Publication Date
20260506
Application Date
20210301

Claims (12)

  1. A method of decoding of a picture from a video bitstream implemented by a decoding device, the bitstream including a slice header of a current slice and data representing the current slice, the method comprising: obtaining a parameter used to derive the number of tiles in the current slice from the slice header, in case that a presence condition is satisfied, wherein the presence condition comprises: the slice address of the current slice is not the address of the last tile in the picture where the current slice located, wherein the address of each slice in the picture is given by the starting tile of the slice, wherein the value of the parameter of the current slice is inferred to be equal to a default value, in case that the presence condition is not satisfied; reconstructing the current slice using the number of tiles in the current slice and the data representing the current slice.
  2. The method of claim 1, wherein the slice address of the current slice being the address of the last tile in the picture comprises determining that the number of tiles in the picture minus the slice address of the current slice is equal to 1.
  3. The method of claim 1, wherein the slice address of the current slice not being the address of the last tile in the picture comprises determining that the number of tiles in the picture minus the slice address of the current slice is greater than 1.
  4. The method according to any one of claims 1 to 3, wherein the value of the parameter of the current slice is inferred to be equal to 0.
  5. The method according to any one of claims 1 to 4, wherein the condition further comprises: determining that the current slice is in raster-scan mode.
  6. The method according to any one of claims 1 to 5, wherein reconstructing the current slice using the number of tiles in the current slice comprises: determining a scan order of the coding tree units in the current slice using the number of tiles in the current slice; and reconstructing the coding tree units in the current slice using the scan order.
  7. A method for encoding of a picture into a video bitstream implemented by an encoding device, the bitstream including a slice header of a current slice and data representing the current slice, the method comprising: encoding a parameter used to derive the number of tiles in the current slice and including the parameter in the slice header, in case that a presence condition is satisfied, wherein the presence condition comprises: the slice address of the current slice is not the address of the last tile in the picture where the current slice located, wherein the address of each slice in the picture is given by the starting tile of the slice, wherein the parameter of the current slice is not present in the bitstream, in case that the presence condition is not satisfied.
  8. An apparatus for decoding a picture from a video bitstream, the bitstream including a slice header of a current slice and data representing the current slice, the apparatus comprising: an obtaining unit configured to obtain a parameter used to derive the number of tiles in the current slice from the slice header, in case that a presence condition is satisfied, wherein the presence condition comprises: the slice address of the current slice is not the address of the last tile in the picture where the current slice located, wherein the address of each slice in the picture is given by the starting tile of the slice, wherein the value of the parameter of the current slice is inferred to be equal to a default value, in case that the presence condition is not satisfied; a reconstructing unit configured to reconstruct the current slice using the number of tiles in the current slice and the data representing the current slice.
  9. An apparatus for encoding of a picture into a coded video bitstream, the bitstream including a slice header of a current slice and data representing the current slice, the apparatus comprising: an encoding unit configured to encode a parameter used to derive the number of tiles in the current slice and to include the parameter in the slice header, in case that a presence condition is satisfied, wherein the presence condition comprises: the slice address of the current slice is not the address of the last tile in the picture where the current slice located, wherein the slice address of each slice in the picture is given by the starting tile of the slice, wherein the encoding unit is configured to not include the parameter of the current slice in the bitstream, in case that the presence condition is not satisfied.
  10. A computer program product comprising program code for performing the method according to any one of claims 1 - 7 when executed on a computer or a processor.
  11. A non-transitory computer-readable medium carrying a program code which, when executed by a computer device, causes the computer device to perform the method of any one of claims 1 - 7.
  12. A video bitstream, the bitstream including a slice header of a current slice and data representing the current slice, wherein the slice header comprises a slice address of the current slice; wherein in case that a presence condition is satisfied, the slice header further comprises a parameter used to derive the number of tiles in the current slice from the slice header, and the presence condition comprises: the slice address of the current slice is not the address of the last tile in the picture where the current slice located, wherein the slice address of each slice in the picture is given by the starting tile of the slice, wherein the parameter of the current slice is not present in the video bitstream, in case that the presence condition is not satisfied.

Description

TECHNICAL FIELD Embodiments of the present application (disclosure) generally relate to the field of picture processing and more particularly to simplifying signalling slice header syntax elements. BACKGROUND Video coding (video encoding and decoding) is used in a wide range of digital video applications, for example broadcast digital TV, video transmission over internet and mobile networks, real-time conversational applications such as video chat, video conferencing, DVD and Blu-ray discs, video content acquisition and editing systems, and camcorders of security applications. The amount of video data needed to depict even a relatively short video can be substantial, which may result in difficulties when the data is to be streamed or otherwise communicated across a communications network with limited bandwidth capacity. Thus, video data is generally compressed before being communicated across modem day telecommunications networks. The size of a video could also be an issue when the video is stored on a storage device because memory resources may be limited. Video compression devices often use software and/or hardware at the source to code the video data prior to transmission or storage, thereby decreasing the quantity of data needed to represent digital video images. The compressed data is then received at the destination by a video decompression device that decodes the video data. With limited network resources and ever-increasing demands of higher video quality, improved compression and decompression techniques that improve compression ratio with little to no sacrifice in picture quality are desirable. In order to improve the compression performances by conditionally omitting from the bitstream syntax elements that, under speficic circumstances, happen to be redundant, the following prior art document (which is VVC Draft 8): BROSS B ET AL: "Versatile Video Coding (Draft 8)", 17. JVET MEETING; 7-17 Jan. 2020; BRUSSELS; (THE JOINT VIDEO EXPLORATION TEAM OF ISO/IEC JTC1/SC29/WG11 AND ITU-T SG.16 ), no. JVET-Q2001, 27 Feb. 2020, Retrieved from the Internet: URL:http://phenix.int-evry.fr/jvet/doc_end_user/documents/17_Brussels/wg11/JVET-Q2001-v14.zip JVET-Q2001-vD.docxdiscloses syntax element num_tiles_in_slice_minus1 to be conditionally present in the slice header. The presence condition considers rect_slice_flag and whether NumTilesInPics>1, see D1, section 7.3.7.1. SUMMARY Embodiments of the present disclosure provide apparatuses and methods for encoding and decoding, as well as a computer program product, a non-transitory computer-readable medium carrying a program code and a video bistream, according to the independent claims. The present invention provides: A method of decoding of a picture from a video bitstream implemented by a decoding device, the bitstream including a slice header of a current slice and data representing the current slice, the method comprising: obtaining a parameter (for example, um_tiles_in_slice_minus1) used to derive the number of tiles in the current slice from the slice header, in case that a condition is satisfied, wherein the condition comprises: the slice address (for example, slice_address) of the current slice is not the address of the last tile in the picture where the current slice located; reconstructing the current slice using the number of tiles in the current slice and the data representing the current slice.The method includes also the further features mentioned in appended claim 1. In the method, as described above, the slice address of the current slice being the address of the last tile in the picture may comprise determining that the number of tiles in the picture minus the slice address of the current slice is equal to 1. In the method, as described above, the slice address of the current slice not being the address of the last tile in the picture may comprise determining that the number of tiles in the picture (for example, NumTilesInPic) minus the slice address of the current slice is greater than 1. Thus, according to the present invention the presence of the picture header structure in the slice header may be used to control the presence of the slice address and the number of tiles in the slice indications. If there is a single slice in a picture the slice address should be equal to the first tile in the picture and the number of tiles in the slice should be equal to the number of tiles in the picture. This may thus enhance compression efficiency. In the method as described above, the value of the parameter of the current slice is inferred to be equal to a default value when the condition is not satisfied. In the method as described above, the default value may be equal to 0. In the method as described above, the condition may further comprise: determining that the current slice is in raster-scan mode. In the method as described above, reconstructing the current slice using the number of tiles in the current slice may comprise: determining a scan order of t