Hypothetical reference decoder for gradual decoding refresh

1 . A non-transitory computer readable medium comprising a computer program product for use by a video coding device, the computer program product comprising computer executable instructions stored on the non-transitory computer readable medium such that when executed by a processor cause the video coding device to:

receive a bitstream comprising a gradual decoding refresh (GDR) access unit (AU) and a buffering period (BP) supplemental enhancement information (SEI) message associated with the GDR AU; and

decode a picture in the GDR AU and the BP SEI message,

wherein a no output of prior pictures flag is set in a header when the picture is a GDR picture.

2 . The non-transitory computer readable medium of claim 1 , wherein the BP SEI message provides an initial coded picture buffer (CPB) removal delay for initialization of a hypothetical reference decoder (HRD) at a position of the GDR AU in decoding order.

3 . The non-transitory computer readable medium of claim 1 , wherein the header is associated with the picture in the GDR AU.

4 . The non-transitory computer readable medium of claim 1 , wherein the bitstream comprises another header associated with the picture, and wherein the another header comprises a picture order count least significant bit value and a recovery picture order count value.

5 . The non-transitory computer readable medium of claim 4 , wherein the picture order count least significant bit value is positioned before the recovery picture order count value in the header associated with the picture.

6 . The non-transitory computer readable medium of claim 1 , wherein the BP SEI message contains a parameter indicating a decoder is capable of decoding the bitstream.

7 . The non-transitory computer readable medium of claim 1 , wherein the picture is the GDR picture when the picture includes a region coded according to inter-prediction and a region coded according to intra-prediction.

8 . An encoder comprising:

one or more processors configured to:

encode into a bitstream a gradual decoding refresh (GDR) access unit (AU) and a buffering period (BP) supplemental enhancement information (SEI) message associated with the GDR AU;

initialize a hypothetical reference decoder (HRD) based on the BP SEI message; and

perform a conformance test on the bitstream using the HRD,

wherein a no output of prior pictures flag is set in a header when a picture in the GDR AU is a GDR picture.

9 . The encoder of claim 8 , wherein the BP SEI message includes an initial coded picture buffer (CPB) removal delay for initialization of the HRD at a position of the GDR AU in decoding order.

10 . The encoder of claim 8 , wherein the header is associated with a picture in the GDR AU.

11 . The encoder of claim 8 , wherein the one or more processors are further configured to encode another header associated with a picture in the GDR AU, wherein the header comprises a picture order count least significant bit value and a recovery picture order count value.

12 . The encoder of claim 11 , wherein the picture order count least significant bit value is positioned before the recovery picture order count value in the header associated with the picture.

13 . The encoder of claim 8 , wherein the BP SEI message contains a parameter indicating a decoder is capable of decoding the bitstream.

14 . The encoder of claim 8 , wherein a picture is the GDR picture when the picture includes a region coded according to inter-prediction and a region coded according to intra-prediction.

15 . A non-transitory computer-readable storage medium storing a bitstream that, when parsed by a coding device, is used by the coding device to generate a video, the bitstream comprising:

a gradual decoding refresh (GDR) access unit (AU) and a buffering period (BP) supplemental enhancement information (SEI) message associated with the GDR AU,

wherein the bitstream is configured to:

cause the coding device to initialize a hypothetical reference decoder (HRD) based on the BP SEI message; and

cause the coding device to perform a conformance test on the bitstream using the HRD, and

wherein a no output of prior pictures flag is set in a header when a picture in the GDR AU is a GDR picture.

16 . The non-transitory computer-readable storage medium of claim 15 , wherein the BP SEI message includes an initial coded picture buffer (CPB) removal delay for initialization of the HRD at a position of the GDR AU in decoding order.

17 . The non-transitory computer-readable storage medium of claim 15 , wherein the header is associated with a picture in the GDR AU.

18 . The non-transitory computer-readable storage medium of claim 15 , wherein the bitstream further comprises another header associated with a picture in the GDR AU, and wherein the header comprises a picture order count least significant bit value and a recovery picture order count value.

19 . The non-transitory computer-readable storage medium of claim 18 , wherein the picture order count least significant bit value is positioned before the recovery picture order count value in the header associated with the picture.

20 . The non-transitory computer-readable storage medium of claim 15 , wherein the BP SEI message contains a parameter indicating a decoder is capable of decoding the bitstream.