Methods for signaling virtual boundaries and wrap-around motion compensation
The present disclosure provides methods for picture processing. The method can include: receiving a bitstream comprising a set of pictures; determining, according to the received bitstream, whether a virtual boundary is signaled at a sequence level for the set of pictures; in response to the virtual boundary being signaled at the sequence level, determining a position of the virtual boundary for the set of pictures, the position being bounded by a range signaled in the received bitstream; and disabling in-loop filtering operations across the virtual boundary.
1. A method of decoding a bitstream to output one or more pictures for a video stream, the method comprising:
receiving a bitstream associated with a video sequence; and
decoding, using coded information of the bitstream, the video sequence,
wherein the decoding comprises:
determining, according to the bitstream, whether a resolution of a first picture in the video sequence is different from a resolution of a reference picture associated with the first picture;
in response to the resolution of the first picture being different from the resolution of the reference picture associated with the first picture, determining that wrap-around motion compensation is disabled for the first picture;
determining, based on a first flag signaled in the bitstream, whether a picture resolution is allowed to be changed within the video sequence; and
determining, based on a second flag signaled in the bitstream, whether information of virtual boundaries is signaled in a sequence parameter set (SPS),
wherein when the first flag has a value indicating that the picture resolution is allowed to be changed within the video sequence, the second flag has a value indicating that the information of virtual boundaries is not signaled in the SPS.
2. The method of claim 1 , wherein when the value of the first flag is equal to 1, the value of the second flag is equal to 0.
3. The method of claim 1 , wherein the first flag and second flag are signaled in the SPS.
4. The method of claim 3 , wherein the decoding comprises:
determining, based on the second flag, whether the information of virtual boundaries is signaled in the SPS.
5. The method of claim 1 , wherein the decoding comprises:
determining, based on a first parameter signaled in the bitstream, a maximum width or height of each picture of the video sequence; and
determining, based on a second parameter signaled in the bitstream, a location of a virtual boundary for the video sequence,
wherein a value of the second parameter is bounded by a range determined by a value of the first parameter.
6. The method of claim 5 , wherein the range is determined by a smallest integer that is greater than or equal to a quotient of the value of the first parameter divided by 8.
7. The method of claim 5 , wherein the value of the first parameter is in units of luma samples.
8. The method of claim 5 , wherein the first parameter and third second parameter are signaled in the SPS.
9. The method of claim 1 , further comprising:
determining, based on a first parameter signaled in the bitstream, a maximum width or height of each picture of the video sequence;
determining, based on a second parameter signaled in a picture parameter set (PPS) of the bitstream, a width or height of a decoded picture referring to the PPS,
wherein when the first flag has a value indicating that the picture resolution is not allowed to be changed within the video sequence, the second parameter has a value equal to a value of the first parameter.
10. A method of encoding a video sequence into a bitstream, the method comprising:
receiving a video sequence;
encoding one or more pictures of the video sequence; and
generating a bitstream,
wherein the encoding comprises:
determining whether a resolution of a first picture in the video sequence is different from a resolution of a reference picture associated with the first picture;
in response to the resolution of the first picture being different from the resolution of the reference picture associated with the first picture, disabling wrap-around motion compensation for the first picture;
encoding a first flag indicating whether a picture resolution is allowed to be changed within the video sequence;
encoding, based on a value of the first flag, a second flag indicating whether information of virtual boundaries is signaled in a sequence parameter set (SPS),
wherein when the value of the first flag indicating that the picture resolution is allowed to be changed within the video sequence, the encoded second flag has a value indicating that the information of virtual boundaries is not signaled in the SPS.
11. The method of claim 10 , wherein when the value of the first flag is equal to 1, the value of the second flag is equal to 0.
12. The method of claim 10 , wherein the encoding comprises:
encoding the first flag and second flag into the SPS.
13. The method of claim 12 , wherein the encoded second flag has a value indicating that the information of virtual boundaries is signaled in the bitstream, and the encoding comprises:
encoding the information of virtual boundaries into the SPS.
14. The method of claim 10 , wherein the encoding comprises:
encoding a first parameter indicating a maximum width or height of each picture of the video sequence; and
encoding a second parameter indicating a location of a virtual boundary for the video sequence,
wherein a value of the second parameter is bounded by a range determined by a value of the first parameter.
15. The method of claim 14 , wherein the encoding comprises:
determining the range based on a smallest integer that is greater than or equal to a quotient of the value of the first parameter divided by 8.
16. The method of claim 14 , wherein the value of the first parameter is in units of luma samples.
17. The method of claim 14 , wherein the encoding comprises:
encoding the first parameter and second parameter into to the SPS.
18. The method of claim 10 , further comprising:
encoding a first parameter indicating a maximum width or height of each picture of the video sequence;
encoding a second parameter signaled in a picture parameter set (PPS) of the bitstream, the second parameter indicating a width or height of an encoded picture referring to the PPS,
wherein when the first flag has a value indicating that the picture resolution is not allowed to be changed within the video sequence, the second parameter has a value equal to a value of the first parameter.
19. A method of storing a bitstream associated with a video sequence, the method comprising:
determining whether a resolution of a first picture in the video sequence is different from a resolution of a reference picture associated with the first picture;
generating the bitstream based on the determining, wherein when the resolution of the first picture is different from the resolution of the reference picture associated with the first picture, wrap-around motion compensation is disabled for the first picture;
encoding, into the bitstream, a first flag indicating whether a picture resolution is allowed to be changed within the video sequence;
encoding, into the bitstream, a second flag indicating whether information of virtual boundaries is signaled in a sequence parameter set (SPS) that the video sequence refers to, wherein when a value of the first flag indicates that the picture resolution is allowed to be changed within the video sequence, the second flag has a value indicating that the information of virtual boundaries is not signaled in the SPS; and
storing the bitstream in a non-transitory computer-readable storage medium.
20. The method of claim 19 , further comprising:
encoding, into the bitstream, a first parameter indicating a maximum width or height of each picture of the video sequence; and
encoding, into the bitstream, a second parameter indicating a location of a virtual boundary for the video sequence,
wherein a value of the second parameter is bounded by a range determined by a value of the first parameter.