Methods and devices for coding binary symbols as N-tuples

1. A method of encoding video in a video encoder to output a bitstream of encoded data for a coefficient group containing a plurality of transform domain coefficients, the method comprising:

encoding a significant-coefficient flag for each of the transform domain coefficients in a scan order within the coefficient group, each significant-coefficient flag having a corresponding greater-than-one flag;

partitioning the greater-than-one flags into a plurality of non-overlapping n-tuples of greater-than-one flags, each n-tuple corresponding to n consecutive significant-coefficient flags in the scan order, wherein n is greater than one; and

for each n-tuple, determining a tuple value based on the greater-than-one flags in the n-tuple and on the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple, and

if the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple are all zero, foregoing encoding the tuple value, and

otherwise, encoding the tuple value in the bitstream.

2. The method claimed in claim 1 , wherein the coefficient group includes sixteen coefficients, wherein the coefficient group has sixteen significant-coefficient flags, and wherein the coefficient group has 8 n-tuples.

3. The method claimed in claim 1 , wherein the tuple value is a logic function of the greater-than-one flags in the n-tuple and the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple.

4. The method claimed in claim 1 , wherein the tuple value is a logic function of the greater-than-one flags in the n-tuple.

5. The method claimed in claim 4 , wherein n is two and the logic function is a logical OR or a logical AND.

6. The method claimed in claim 1 , wherein n is two and wherein at least one of the n-tuples has significant-coefficient flags corresponding to the greater-than-one flags in said at least one of the n-tuples that include a non-zero flag and a zero flag, and wherein the tuple value for said at least one of the n-tuples is the value of the greater-than-one flag corresponding to the non-zero flag.

7. The method claimed in claim 6 , wherein another of the n-tuples includes greater-than-one flags corresponding to two non-zero significant-coefficient flags, and wherein the tuple value for said another of the n-tuples is a logic function of the greater-than-one flags of said another of the n-tuples.

8. The method claimed in claim 7 , wherein encoding the tuple value of the another of the n-tuples further includes

encoding a first of the greater-than-one flags for said another of the n-tuples using equiprobable coding;

determining whether the value of a second of the greater-than-one flags for said another of the n-tuples may be inferred from the first of the greater-than-one flags and,

if so, foregoing encoding the second of the greater-than-one flags and,

otherwise, encoding the second of the greater-than-one flags using equiprobable coding.

9. The method claimed in claim 1 , wherein n is greater than two.

10. A method of decoding a bitstream of encoded video in a video decoder to reconstruct a plurality of transform domain coefficients for a coefficient group, the method comprising:

decoding a significant-coefficient flag for each of the transform domain coefficients in a scan order within the coefficient group, each significant-coefficient flag having a corresponding greater-than-one flag;

based on a partitioning of the greater-than-one flags into a plurality of non-overlapping n-tuples of greater-than-one flags, each n-tuple corresponding to n consecutive significant-coefficient flags in the scan order, reconstructing a tuple value for each n-tuple, based on the greater-than-one flags in the n-tuple and on the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple, wherein,

if the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple are all zero, the tuple value is inferred, without decoding, to be zero, and

otherwise, decoding the tuple value from the bitstream,

and wherein n is greater than one; and

reconstructing the greater-than-one flags based on the reconstructed tuple values.

11. The method claimed in claim 10 , wherein the coefficient group includes sixteen coefficients, wherein the coefficient group has sixteen significant-coefficient flags, and wherein the coefficient group has 8 n-tuples.

12. The method claimed in claim 10 , wherein the tuple value is a logic function of the greater-than-one flags in the n-tuple and the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple.

13. The method claimed in claim 10 , wherein the tuple value is a logic function of the greater-than-one flags in the n-tuple.

14. The method claimed in claim 13 , wherein n is two and the logic function is a logical OR or a logical AND.

15. The method claimed in claim 10 , wherein n is two and wherein at least one of the n-tuples has significant-coefficient flags corresponding to the greater-than-one flags in said at least one of the n-tuples that include a non-zero flag and a zero flag, and wherein the tuple value for said at least one of the n-tuples is the value of the greater-than-one flag corresponding to the non-zero flag.

16. The method claimed in claim 15 , wherein another of the n-tuples includes greater-than-one flags corresponding to two non-zero significant-coefficient flags, and wherein the tuple value for said another of the n-tuples is a logic function of the greater-than-one flags of said another of the n-tuples.

17. The method claimed in claim 16 , wherein decoding the tuple value of said another of the n-tuples further includes

decoding a first of the greater-than-one flags for said another of the n-tuples using equiprobable coding;

determining whether the value of a second of the greater-than-one flags for said another of the n-tuples may be inferred from the first of the greater-than-one flags and,

if so, foregoing decoding the second of the greater-than-one flags and,

otherwise, decoding the second of the greater-than-one flags using equiprobable coding.

18. The method claimed in claim 10 , wherein n is greater than two.

19. An encoder for encoding video in a video encoder to output a bitstream of encoded data for a coefficient group containing a plurality of transform domain coefficients, the encoder comprising:

a processor;

a memory; and

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

encode a significant-coefficient flag for each of the transform domain coefficients in a scan order within the coefficient group, each significant-coefficient flag having a corresponding greater-than-one flag,

partition the greater-than-one flags into a plurality of non-overlapping n-tuples of greater-than-one flags, each n-tuple corresponding to n consecutive significant-coefficient flags in the scan order, wherein n is greater than one, and

for each n-tuple, determine a tuple value based on the greater-than-one flags in the n-tuple and on the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple, and

if the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple are all zero, forego encoding the tuple value, and

otherwise, encode the tuple value in the bitstream.

20. A decoder for decoding a bitstream of encoded video in a video decoder to reconstruct a plurality of transform domain coefficients for a coefficient group, the decoder comprising:

a processor;

a memory; and

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

decode a significant-coefficient flag for each of the transform domain coefficients in a scan order within the coefficient group, each significant-coefficient flag having a corresponding greater-than-one flag,

based on a partitioning of the greater-than-one flags into a plurality of non-overlapping n-tuples of greater-than-one flags, each n-tuple corresponding to n consecutive significant-coefficient flags in the scan order, reconstruct a tuple value for each n-tuple, based on the greater-than-one flags in the n-tuple and on the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple, wherein,

if the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple are all zero, the tuple value is inferred, without decoding, to be zero, and

otherwise, decoding the tuple value from the bitstream,

and wherein n is greater than one, and

reconstructing the greater-than-one flags based on the reconstructed tuple values.

21. A non-transitory processor-readable medium storing processor-executable instructions for encoding video in a video encoder to output a bitstream of encoded data for a coefficient group containing a plurality of transform domain coefficients, wherein the instructions, when executed, are to cause one or more processors to:

encode a significant-coefficient flag for each of the transform domain coefficients in a scan order within the coefficient group, each significant-coefficient flag having a corresponding greater-than-one flag;

partition the greater-than-one flags into a plurality of non-overlapping n-tuples of greater-than-one flags, each n-tuple corresponding to n consecutive significant-coefficient flags in the scan order, wherein n is greater than one; and

for each n-tuple, determine a tuple value based on the greater-than-one flags in the n-tuple and on the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple, and

if the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple are all zero, forego encoding the tuple value, and

otherwise, encode the tuple value in the bitstream.

22. A non-transitory processor-readable medium storing processor-executable instructions for decoding a bitstream of encoded video in a video decoder to reconstruct a plurality of transform domain coefficients for a coefficient group, wherein the instructions, when executed, are to cause one or more processors to:

decode a significant-coefficient flag for each of the transform domain coefficients in a scan order within the coefficient group, each significant-coefficient flag having a corresponding greater-than-one flag,

based on a partitioning of the greater-than-one flags into a plurality of non-overlapping n-tuples of greater-than-one flags, each n-tuple corresponding to n consecutive significant-coefficient flags in the scan order, reconstruct a tuple value for each n-tuple, based on the greater-than-one flags in the n-tuple and on the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple, wherein,

if the significant-coefficient flags corresponding to the greater-than-one flags in the n-tuple are all zero, the tuple value is inferred, without decoding, to be zero, and

otherwise, decoding the tuple value from the bitstream,

and wherein n is greater than one, and

reconstructing the greater-than-one flags based on the reconstructed tuple values.

23. The method of claim 1 , wherein each significant-coefficient flag has a corresponding greater-than-one flag irrespective of whether that significant-coefficient flag is non-zero.