BITSTREAM CONFORMANCE TEST IN VIDEO CODING

• US 20140086303A1
• Filed: 06/14/2013
• Published: 03/27/2014
• Est. Priority Date: 09/24/2012
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: WANG, Ye-Kui
• Granted Patent: US 9,351,005 B2
• Time in Patent Office: Days
• US Class Current: 375/240.02
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/31 in the temporal domain
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards

Abstract

A device performs a decoding process as part of a bitstream conformance test. As part of the decoding process, the device performs a bitstream extraction process to extract, from a bitstream, an operation point representation of an operation point defined by a target set of layer identifiers and a target highest temporal identifier. The target set of layer identifiers contains values of layer identifier syntax elements present in the operation point representation, the target set of layer identifiers being a subset of values of layer identifier syntax elements of the bitstream. The target highest temporal identifier is equal to a greatest temporal identifier present in the operation point representation, the target highest temporal identifier being less than or equal to a greatest temporal identifier present in the bitstream. The device decodes network abstraction layer (NAL) units of the operation point representation.

Claims

1. A method of processing video data, the method comprising:

performing a bitstream conformance test that determines whether a bitstream conforms to a video coding standard, wherein performing the bitstream conformance test comprises performing a decoding process, wherein performing the decoding process comprises;

performing a bitstream extraction process that extracts, from the bitstream, an operation point representation of an operation point defined by a target set of layer identifiers and a target highest temporal identifier,

wherein the target set of layer identifiers contains values of layer identifier syntax elements present in the operation point representation, the target set of layer identifiers being a subset of values of layer identifier syntax elements of the bitstream,

wherein the target highest temporal identifier is equal to a greatest temporal identifier present in the operation point representation, the target highest temporal identifier being less than or equal to a greatest temporal identifier present in the bitstream; and

decoding network abstraction layer (NAL) units of the operation point representation.

2. The method of claim 1, wherein:

the operation point is a first operation point,

the method further comprises performing the decoding process a second time,

when the decoding process is performed the second time, the decoding process is not performed as part of the bitstream conformance test, and

performing the decoding process for the second time comprises;

receiving, from an external source, a second target set of layer identifiers and a second target highest temporal identifier, the second target set of layer identifiers containing values of layer identifier syntax elements present in an operation point representation of a second operation point that is defined by the second target set of layer identifiers and the second target highest temporal identifier, the second target highest temporal identifier being equal to a greatest temporal identifier present in the operation point representation of the second operation point;

performing the bitstream extraction process to extract, from the bitstream, the operation point representation of the second operation point; and

decoding NAL units of the operation point representation of the second operation point.

3. The method of claim 1, wherein:

the operation point is a first operation point,

the method further comprises performing the decoding process a second time,

when the decoding process is performed the second time, the decoding process is not performed as part of the bitstream conformance test, and

performing the decoding process for the second time comprises;

performing the bitstream extraction process to extract, from the bitstream, an operation point representation of a second operation point,

wherein 0 is the only value indicated by layer identifier syntax elements present in the operation point representation of the second operation point, and

wherein the greatest temporal identifier present in the bitstream is equal to a greatest temporal identifier present in the operation point representation of the second operation point; and

decoding NAL units of the operation point representation of the second operation point.

4. The method of claim 1, wherein performing the bitstream conformance test comprises:

selecting the operation point;

determining the target set of layer identifiers of the operation point and the target highest temporal identifier of the operation point;

selecting a set of hypothetical reference decoder (HRD) parameters applicable to the operation point; and

using the selected set of HRD parameters to configure a HRD that performs the decoding process.

5. The method of claim 4,

wherein performing the decoding process further comprises decoding, from a sequence parameter set (SPS), an array of syntax elements, wherein each of the syntax elements in the array indicates a maximum required size of a decoded picture buffer (DPB) of the HRD;

and

wherein performing the bitstream conformance test comprises;

determining, based on the target highest temporal identifier, a particular syntax element in the array; and

determining that the bitstream is not in conformance with the video coding standard when a value indicated by the particular syntax element is greater than a maximum DPB size.

6. The method of claim 4,

wherein performing the decoding process comprises decoding, from a SPS, an array of syntax elements that each indicate a maximum required size of a DPB of the HRD;

and

wherein performing the bitstream conformance test comprises;

determining, based on the target highest temporal identifier, a particular syntax element in the array; and

performing a bumping process that empties one or more picture storage buffers of the DPB when a current picture is not an Instantaneous Decoding Refresh (IDR) picture or a Broken Link Access (BLA) picture and the number of pictures in the DPB marked as needed for output is greater than a value indicated by the particular syntax element.

7. The method of claim 4, wherein:

wherein performing the decoding process comprises decoding, from a SPS, an array of syntax elements that each indicate a maximum required size of a DPB of the HRD; and

wherein performing the bitstream conformance test comprises;

determining, based on the target highest temporal identifier, a particular syntax element in the array; and

performing a bumping process that empties one or more picture storage buffers of the DPB when a current picture is not an IDR picture or a BLA picture and the number of pictures in the DPB is indicated by the particular syntax element.

8. The method of claim 4,

wherein performing the decoding process comprises decoding, from a SPS, an array of syntax elements that each indicate a maximum required size of a DPB of the HRD;

wherein performing the bitstream conformance test comprises determining, based on the target highest temporal identifier, a particular syntax element in the array; and

wherein a number of picture storage buffers in the DPB is indicated by the particular syntax element.

9. The method of claim 4,

wherein performing the decoding process comprises:

decoding, from an SPS active for a current picture, a first array of syntax elements that each indicate a maximum required size of a DPB of the HRD;

decoding, from an SPS active for a preceding picture, a second array of syntax elements that each indicate a maximum required size of the DPB of the HRD;

determining, based on the target highest temporal identifier, a first syntax element in the first array;

determining, based on the target highest temporal identifier, a second syntax element in the second array; and

when the current picture is an IDR picture or a BLA picture and a value indicated by the first syntax element is different than a value indicated by the second syntax element, inferring a value of a third syntax element regardless of a value indicated by the third syntax element, wherein the third syntax element specifies how previously-decoded pictures in the DPB are treated after decoding of an IDR picture or BLA picture.

10. The method of claim 4,

wherein performing the decoding process comprises decoding a HRD parameters syntax structure that includes the selected set of HRD parameters, wherein the selected set of HRD parameters includes an array of syntax elements that each indicate a number of alternative coded picture buffer (CPB) specifications in the bitstream;

and

wherein performing the bitstream conformance test comprises;

selecting, based on the target highest temporal identifier, a particular syntax element in the array;

selecting a scheduler selection index in a range of 0 to a value indicated by the particular syntax element; and

determining, based at least in part on the scheduler selection index, an initial CPB removal delay of a CPB of the HRD.

11. The method of claim 4,

wherein performing the decoding process further comprises decoding, from a SPS, an array of syntax elements, wherein each of the syntax elements in the array indicates a maximum required size of a DPB of the HRD;

and

wherein performing the bitstream conformance test comprises;

determining, based on the target highest temporal identifier, a particular syntax element in the array; and

determining, based at least in part on whether a number of decoded pictures in the DPB is less than or equal to the maximum of 0 and a value indicated by the particular syntax element minus1, whether the bitstream conforms to the video coding standard.

12. A device comprising one or more processors configured to:

perform a bitstream conformance test that determines whether a bitstream conforms to a video coding standard;

when the one or more processors perform the bitstream conformance test, perform a decoding process, wherein when the one or more processors perform the decoding process, the one or more processors;

perform a bitstream extraction process that extracts, from the bitstream, an operation point representation of an operation point defined by a target set of layer identifiers and a target highest temporal identifier,

wherein the target set of layer identifiers contains values of layer identifier syntax elements present in the operation point representation, the target set of layer identifiers being a subset of values of layer identifier syntax elements of the bitstream,

wherein the target highest temporal identifier is equal to a greatest temporal identifier present in the operation point representation, the target highest temporal identifier being less than or equal to a greatest temporal identifier present in the bitstream; and

decode network abstraction layer (NAL) units of the operation point representation.

13. The device of claim 12, wherein:

the operation point is a first operation point,

the one or more processors are configured to perform the decoding process a second time,

when the decoding process is performed the second time, the decoding process is not performed as part of the bitstream conformance test, and

the one or more processors are configured such that when the one or more processors perform the decoding process for the second time, the one or more processors;

receive, from an external source, a second target set of layer identifiers and a second target highest temporal identifier, the second target set of layer identifiers containing values of layer identifier syntax elements present in an operation point representation of a second operation point that is defined by the second target set of layer identifiers and the second target highest temporal identifier, the second target highest temporal identifier being equal to a greatest temporal identifier present in the operation point representation of the second operation point;

perform the bitstream extraction process to extract, from the bitstream, the operation point representation of the second operation point; and

decode NAL units of the operation point representation of the second operation point.

14. The device of claim 12, wherein:

the operation point is a first operation point,

the one or more processors are configured to perform the decoding process a second time,

when the decoding process is performed the second time, the decoding process is not performed as part of the bitstream conformance test, and

the one or more processors are configured such that when the one or more processors perform the decoding process for the second time, the one or more processors;

perform the bitstream extraction process to extract, from the bitstream, an operation point representation of a second operation point,

wherein 0 is the only value indicated by layer identifier syntax elements present in the operation point representation of the second operation point, and

wherein the greatest temporal identifier present in the bitstream is equal to a greatest temporal identifier present in the operation point representation of the second operation point; and

decode NAL units of the operation point representation of the second operation point.

15. The device of claim 12, wherein the one or more processors are configured such that when the one or more processors perform the bitstream conformance test, the one or more processors:

select the operation point;

determine the target set of layer identifiers of the operation point and the target highest temporal identifier of the operation point;

select a set of hypothetical reference decoder (HRD) parameters applicable to the operation point; and

use the selected set of HRD parameters to configure a HRD that performs the decoding process.

16. The device of claim 15,

wherein the one or more processors are configured such that when the one or more processors perform the decoding process, the one or more processors decode, from a sequence parameter set (SPS), an array of syntax elements, wherein each of the syntax elements in the array indicates a maximum required size of a decoded picture buffer (DPB) of the HRD;

and

wherein when the one or more processors perform the bitstream conformance test, the one or more processors;

determine, based on the target highest temporal identifier, a particular syntax element in the array; and

determine that the bitstream is not in conformance with the video coding standard when a value indicated by the particular syntax element is greater than a maximum DPB size.

17. The device of claim 15,

wherein when the one or more processors perform the decoding process, the one or more processors decode, from a SPS, an array of syntax elements that each indicate a maximum required size of a DPB of the HRD;

and

wherein when the one or more processors perform the bitstream conformance test, the one or more processors;

determine, based on the target highest temporal identifier, a particular syntax element in the array; and

perform a bumping process that empties one or more picture storage buffers of the DPB when a current picture is not an Instantaneous Decoding Refresh (IDR) picture or a Broken Link Access (BLA) picture and the number of pictures in the DPB marked as needed for output is greater than a value indicated by the particular syntax element.

18. The device of claim 15, wherein:

wherein when the one or more processors perform the decoding process, the one or more processors decode, from a SPS, an array of syntax elements that each indicate a maximum required size of a DPB of the HRD; and

wherein when the one or more processors perform the bitstream conformance test, the one or more processors;

determine, based on the target highest temporal identifier, a particular syntax element in the array; and

perform a bumping process that empties one or more picture storage buffers of the DPB when a current picture is not an IDR picture or a BLA picture and the number of pictures in the DPB is indicated by the particular syntax element.

19. The device of claim 15,

wherein when the one or more processors perform the decoding process, the one or more processors decode, from a SPS, an array of syntax elements that each indicate a maximum required size of a DPB of the HRD;

wherein when the one or more processors perform the bitstream conformance test, the one or more processors determine, based on the target highest temporal identifier, a particular syntax element in the array; and

wherein a number of picture storage buffers in the DPB is indicated by the particular syntax element.

20. The device of claim 15,

wherein when the one or more processors perform the decoding process, the one or more processors:

decode, from an SPS active for a current picture, a first array of syntax elements that each indicate a maximum required size of a DPB of the HRD;

decode, from an SPS active for a preceding picture, a second array of syntax elements that each indicate a maximum required size of the DPB of the HRD;

determine, based on the target highest temporal identifier, a first syntax element in the first array;

determine, based on the target highest temporal identifier, a second syntax element in the second array; and

when the current picture is an IDR picture or a BLA picture and a value indicated by the first syntax element is different than a value indicated by the second syntax element, infer a value of a third syntax element regardless of a value indicated by the third syntax element, wherein the third syntax element specifies how previously-decoded pictures in the DPB are treated after decoding of an IDR picture or BLA picture.

21. The device of claim 15,

wherein when the one or more processors perform the decoding process, the one or more processors decode a HRD parameters syntax structure that includes the selected set of HRD parameters, wherein the selected set of HRD parameters includes an array of syntax elements that each indicate a number of alternative coded picture buffer (CPB) specifications in the bitstream;

and

wherein when the one or more processors perform the bitstream conformance test, the one or more processors;

select, based on the target highest temporal identifier, a particular syntax element in the array;

select a scheduler selection index in a range of 0 to a value indicated by the particular syntax element; and

determine, based at least in part on the scheduler selection index, an initial CPB removal delay of a CPB of the HRD.

22. The device of claim 15,

wherein when the one or more processors perform the decoding process, the one or more processors decode, from a SPS, an array of syntax elements, wherein each of the syntax elements in the array indicates a maximum required size of a DPB of the HRD;

and

wherein when the one or more processors perform the bitstream conformance test, the one or more processors;

determine, based on the target highest temporal identifier, a particular syntax element in the array; and

determine, based at least in part on whether a number of decoded pictures in the DPB is less than or equal to the maximum of 0 and a value indicated by the particular syntax element minus1, whether the bitstream conforms to the video coding standard.

23. A device comprising:

means for performing a bitstream conformance test that determines whether a bitstream conforms to a video coding standard, wherein performing the bitstream conformance test comprises performing a decoding process, wherein performing the decoding process comprises;

performing a bitstream extraction process that extracts, from the bitstream, an operation point representation of an operation point defined by a target set of layer identifiers and a target highest temporal identifier,

wherein the target set of layer identifiers contains values of layer identifier syntax elements present in the operation point representation, the target set of layer identifiers being a subset of values of layer identifier syntax elements of the bitstream,

wherein the target highest temporal identifier is equal to a greatest temporal identifier present in the operation point representation, the target highest temporal identifier being less than or equal to a greatest temporal identifier present in the bitstream; and

decoding network abstraction layer (NAL) units of the operation point representation.

24. The device of claim 23, wherein performing the bitstream conformance test comprises:

selecting an operation point of the bitstream;

determining the target set of layer identifiers of the operation point and the target highest temporal identifier of the operation point;

selecting a set of hypothetical reference decoder (HRD) parameters applicable to the operation point; and

using the selected set of HRD parameters to configure a HRD that performs the decoding process.

25. A computer-readable storage medium having instructions stored thereon that, when executed by one or more processors of a device, configure the device to:

perform a bitstream conformance test that determines whether a bitstream conforms to a video coding standard, wherein performing the bitstream conformance test comprises performing a decoding process, wherein performing the decoding process comprises;

performing a bitstream extraction process that extracts, from the bitstream, an operation point representation of an operation point defined by a target set of layer identifiers and a target highest temporal identifier,

wherein the target set of layer identifiers contains values of layer identifier syntax elements present in the operation point representation, the target set of layer identifiers being a subset of values of layer identifier syntax elements of the bitstream,

wherein the target highest temporal identifier is equal to a greatest temporal identifier present in the operation point representation, the target highest temporal identifier being less than or equal to a greatest temporal identifier present in the bitstream; and

decoding network abstraction layer (NAL) units of the operation point representation.

26. The computer-readable storage medium of claim 25, wherein the instructions configure the device such that during the bitstream conformance test, the device:

selects an operation point of the bitstream;

determine the target set of layer identifiers of the operation point and the target highest temporal identifier of the operation point;

selects a set of hypothetical reference decoder (HRD) parameters applicable to the operation point; and

uses the selected set of HRD parameters to configure a HRD that performs the decoding process.