Granted Patent B2

US 9,462,286 · App. 13/524,583 · Granted Oct 4, 2016

Inventors: Nguyen Nguyen (Waterloo, CA); Dake He (Waterloo, CA)

Assignee: BlackBerry Limited

H04N19/44H04N19/124H04N19/18H04N19/46

Abstract

Claims (49)

1. A method of decoding a bitstream of encoded video in a video decoder to reconstruct a plurality of greater-than-one flags for a coefficient group, wherein the plurality of greater-than-one flags are grouped in scan order into a plurality of 2-tuples of pairs of greater-than-one flags for the coefficient group, the method comprising:

for each of the plurality of 2-tuples of pairs of greater-than-one flags for the coefficient group,

context-adaptively decoding a tuple-based value from the bitstream for that tuple; and

inferring or decoding the greater-than-one flags for that tuple based on that tuple's decoded tuple-based value, wherein the tuple-based value is a logical OR of the greater-than-one flags in that tuple, and wherein decoding comprises non-context-based bypass decoding, and wherein the inferring or decoding includes

if the tuple-value is zero, inferring that both greater-than-one flags of that tuple are zero, and

if the tuple-value is non-zero, decoding a first greater-than-one flag of the pair for that tuple and, if the first greater-than-one flag is zero, then inferring that a second greater-than-one flag of the pair for that tuple is non-zero and, otherwise, decoding the second greater-than-one flag of the pair.

2. The method claimed in claim 1 , wherein each tuple contains two greater-than-one flags unless a number of greater-than-one flags in the coefficient group is odd, in which case a last tuple in the coefficient group contains one greater-than-one flag and a zero.

3. The method claimed in claim 1 , wherein decoding of greater-than-one flags comprises equiprobability decoding.

4. The method claimed in claim 1 , applied to reconstruct a set of coefficients for the coefficient group and further comprising:

decoding a significant coefficient flag for each coefficient in the coefficient group, each significant coefficient flag indicating whether its corresponding coefficient is non-zero;

decoding additional level information for each coefficient having a magnitude greater-than-one;

decoding sign information for at least one non-zero coefficient; and

reconstructing the set of coefficients based on the decoded significant coefficient flags, the decoded or inferred greater-than-one flags, the decoded additional level information, and the decoded sign information.

5. A method of encoding video in a video encoder to output a bitstream of encoded data by encoding a plurality of greater-than-one flags for a coefficient group, the method comprising:

grouping the greater-than-one flags in scan order into a plurality of non-overlapping 2-tuples of pairs of greater-than-one flags for the coefficient group;

for each of the plurality of 2-tuples of pairs of greater-than-one flags for the coefficient group,

determining a tuple-based value for that tuple as a logical OR of the greater-than-one flags in that tuple;

context-adaptively encoding the tuple-based values in the bitstream; and

for each greater-than-one flag in that tuple, if that greater-than-one flag is not inferable, then encoding that greater-than-one flag in the bitstream, wherein the encoding is non-context-based bypass encoding, including,

if the tuple-value is zero, not encoding either of the pairs of greater-than-one flags, and

if the tuple-value is non-zero, encoding a first greater-than-one flag of the pair for that tuple and, if the first greater-than-one flag is zero, not encoding a second greater-than-one flag of the pair of that tuple and, otherwise, encoding the second greater-than-one flag of the pair.

6. A decoder for decoding a bitstream of encoded video in a video decoder to reconstruct a plurality of greater-than-one flags for a coefficient group, wherein the plurality of greater-than-one flags partitioned in scan order form a plurality of 2-tuples of pairs of greater-than-one flags for the coefficient group, the decoder comprising:

a processor;

a memory; and

a decoding application stored in memory and containing instructions that, when executed, cause the processor to

for each of the plurality of 2-tuples of pairs of greater-than-one flags for the coefficient group,

context-adaptively decode a tuple-based value from the bitstream for that tuple; and

infer or decode the greater-than-one flags for that tuple based on that tuple's decoded tuple-based value, wherein the tuple-based value is a logical OR of the greater-than-one flags in that tuple, and wherein decoding comprises non-context-based bypass decoding, and wherein the processor is to infer or decode by

if the tuple-value is zero, inferring that both greater-than-one flags of that tuple are zero, and

if the tuple-value is non-zero, decoding a first greater-than-one flag of the pair for that tuple and, if the first greater-than-one flag is zero, then inferring that a second greater-than-one flag of the pair for that tuple is non-zero and, otherwise, decoding the second greater-than-one flag of the pair.

7. The decoder claimed in claim 6 , wherein each tuple contains two greater-than-one flags unless a number of greater-than-one flags in the coefficient group is odd, in which case a last tuple in the coefficient group contains one greater-than-one flag and a zero.

8. The decoder claimed in claim 6 , wherein the decoder is configured to decode greater-than-one flags using equiprobability decoding.

9. The decoder claimed in claim 6 , applied to reconstruct a set of coefficients for the coefficient group and wherein the decoder is further configured to:

decode a significant coefficient flag for each coefficient in the coefficient group, each significant coefficient flag indicating whether its corresponding coefficient is non-zero;

decode additional level information for each coefficient having a magnitude greater-than-one;

decode sign information for at least one non-zero coefficient; and

reconstruct the set of coefficients based on the decoded significant coefficient flags, the decoded or inferred greater-than-one flags, the decoded additional level information, and the decoded sign information.

10. A non-transitory processor-readable medium storing processor-executable instructions which, when executed, configures one or more processors to perform the method claimed in claim 1 .

11. An encoder for encoding video in a video encoder to output a bitstream of encoded data by encoding a plurality of greater-than-one flags for a coefficient group, the encoder comprising:

a processor;

a memory; and

an encoding application stored in memory and containing instructions that, when executed, cause the processor to:

group the greater-than-one flags in scan order into a plurality of non-overlapping 2-tuples of pairs of greater-than-one flags for the coefficient group;

for each of the plurality of 2-tuples of pairs of greater-than-one flags for the coefficient group,

determine a tuple-based value for that tuple as a logical OR of the greater-than-one flags in that tuple;

context-adaptively encode the tuple-based values in the bitstream; and

for each greater-than-one flag in that tuple, if that greater-than-one flag is not inferable, then encode that greater-than-one flag in the bitstream using non-context-based bypass encoding, including,

if the tuple-value is zero, not encoding either of the pairs of greater-than-one flags, and

if the tuple-value is non-zero, encoding a first greater-than-one flag of the pair for that tuple and, if the first greater-than-one flag is zero, not encoding a second greater-than-one flag of the pair of that tuple and, otherwise, encoding the second greater-than-one flag of the pair.

Assignments (9)

Continuity (1)