1. A method of encoding a unit of video data, comprising:dividing a transform block of video data into a plurality of transform coefficient sub-sets;determining, for a sub-set of the plurality of transform coefficient sub-sets, whether or not to generate a syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and generating, for the sub-set of the plurality of transform coefficient sub-sets, the syntax element.

3. The method of claim 1, wherein determining, for the sub-set, whether or not to generate the syntax element comprises determining whether generating the syntax element will improve coding efficiency.

4. The method of claim 1, wherein determining whether or not to generate the syntax element comprises comparing a number of potential non-zero coefficients of the sub-set to at least one threshold; and if the number of potential non-zero coefficients of the sub-set is greater than the threshold, generating the syntax element,

5. The method of claim 4, further comprising:determining the number of potential non-zero coefficients based on bow many coefficients of the sub-set have a position alter a last non-zero coefficient of the transform block.

6. The method of claim 1, wherein determining whether or not to generate the syntax element comprises:determining, for a plurality of previously coded transform blocks of video data, an average number of non-zero coefficients included in the subset;comparing the average number of non-zero coefficients included in the sub-set to a threshold; and if the average number of non-zero coefficients is less than the threshold, generating the syntax clement.

7. The method of claim 1, wherein determining whether or not to generate the syntax element comprises;determining whether the subset includes a last non-zero coefficient for the transform block of video data, wherein the syntax element that indicates whether or not the sob-set includes any non-zero coefficients is not generated if the subset includes the last non-zero coefficient.

8. The method of claim 1, further comprising:determining, for each sub-set of the plurality of transform coefficient sub-sets, whether or not to generate the syntax element.

9. A device configured to encode at least one transform block of video data, comprising:a processor configured to:divide a transform block of video data into a plurality of transform coeffient sub-sets;determine, for a sub-set of the plurality of transform coefficient sub-sets, whether or not to generate a syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and generate, for the sub-set of the plurality of transform coefficient sub-sets, the syntax element

11. The device of claim 9, wherein the processor is further configured to:determine, for the sub-set, whether or not to generate the syntax element based on whether generating the syntax element will improve coding efficiency

12. The device of claim 9, wherein the processor is further configured to:determine whether or not to generate the syntax element based on comparing a number of potential non-zero coefficient of the sub-set to at least one threshold; and if the number of potential non-zero coefficients of the sub-set is greater than the threshold, generate the syntax element

13. The device of claim 12, wherein the processor is further configured to:determine the number of potential non-zero coefficients based on how many coefficients of the sub-set have a position after a last non-zero coefficient of the transform block

14. The device of claim 9, wherein the processor 13 further configured to:determine, for a plurality of previously coded transform blocks of video data, an average number of non-zero coefficients included in the subset;compare the average number of non-zero coefficients included in the sub-set to a threshold; and if the average number of non-zero coefficients is less than the threshold, generate the syntax element

15. The device of claim 9, wherein the encoding module is further configured to: determine, for each sub-set of the plurality of transform coefficient sub-sets, whether or not to generate the syntax element

16. The device of claim 9, wherein the processor is further configured to:determining whether the subset includes a last non-zero coefficient for the transform block of video data, wherein the syntax clement that indicates whether or not the sub-set includes any non-zero coefficients is not generated if the subset includes the last non-zero coefficient

17. A computer-readable storage medium that stores instructions that, when executed, cause a computing device to:divide a transform block of video data into a plurality of transform coefficient sub-sets; determine, for a sub-set of the plurality of transform coefficient sub-sets, whether or not to generate a syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and generate, for the sub-set of the plurality of transform coefficient sub-sets, the syntax element

19. The computer-readable storage medium of claim 17, wherein the instructions further cause the computing device to:determine, for the sub-set, whether or riot to generate the syntax element based on whether generating the syntax element will improve coding efficiency.

21. The computer-readable storage medium of claim 20, wherein the instructions further cause the computing device to:determine the number of potential non-zero coefficients based on how many coefficients of the sub-set have a position after a last non-zero coefficient of the transform block.

22. The computer-readable storage medium of claim 17, wherein the instructions further cause the computing device to:determine, for a plurality of previously coded transform blocks of video data, an average number of non-zero coefficients included in the subset;compare the average number of non-zero coefficients included in the sub-set to a threshold; and if the average number of non-zero coefficients is less than the threshold, generate the syntax element.

23. The computer-readable storage medium of claim 17, wherein the instructions further cause the computing device to:determine, for each sub-set of the plurality of transform coefficient sub-sets, whether or not to generate the syntax element,

24, The computer-readable storage medium of claim 17, wherein the instructions further cause the computing device to:determine whether the subset includes a last non-zero coefficient for the transform block of video data, wherein the syntax element that indicates whether or not the sub-set includes any non-zero coefficients is not generated if the subset includes the last non-zero coefficient

25. A device configured to encode at least one transform block of video data, comprising:means for dividing a transform block of video data into a plurality of transform coefficient sub-sets;means for determining, for a sub-set of the plurality of transform coefficient sub-sets, whether or not to generate a syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and means for generating, for the sub-set of the plurality of transform coefficient sub-sets, the syntax element.

27. The device of claim 25, further comprising:means for determining, for the sub-set, whether or not to generate the syntax element based on whether generating the syntax element will improve coding efficiency.

28. The device of claim 25, thither comprising:means for determining whether or not to generate the syntax element based on comparing a number of potential non-zero coefficient of the sub-set to at least one threshold; and means for, if the number of potential non-zero coefficients of the sub-set is greater than the threshold, generating the syntax element.

29, The device of claim 28, further comprising:means for determining the number of potential non-zero coefficients based on how many coefficients of the sub-set have a position after a last non-zero coefficient of the transform block.

30. The device of claim 25, wherein the means for determining whether or not to generate the syntax clement comprise:means for determining, for a plurality of previously coded transform blocks of video data, an average number of non-zero coefficients included in the subset;means for comparing the average number of non-zero coefficients included in the sub-set to a threshold; and means for, if the average number of non-zero coefficients is less than the threshold, generating the syntax clement.

31. The device of claim 25, further comprising:means for determining, for each sub-set of the plurality of transform coefficient sub-sets, whether or not to generate the syntax element.

32. The device of claim 25, further comprising:means for determining whether the subset includes a last non-zero coefficient for the transform block of video data, wherein the syntax element that indicates whether or not the sub-set includes any non-zero coefficients is not generated if the subset includes the last non-zero coefficient,

33. A method of decoding a unit of video data, comprising:dividing a transform block of video data into a plurality of transform coefficient sub-sets; and determining, for a sub-set of the plurality of transform coefficient sub-sets, whether the sub-set includes an associated syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and determining, based on the syntax element, whether or not to decode the sub-set.

34. The method of claim 33, further comprising:if the sub-set does not include the syntax element, decoding the sub-set.

35. The method of claim 34, further comprising:if the sub-set of data does include the syntax element, determining whether to decode the sub-set based on the indication.

36. The method of claim 35, further comprising:if the syntax clement associated with the sub-set has a first value, decoding the sub-set; and if the syntax element has a second value different than the first value, not decoding the sub-set.

37. The method of claim 33, further comprising:determining, for each sub-set of the plurality of transform coefficient sub-sets, whether the sub-set includes an associated syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and determining, based on the syntax element, whether or not to decode the sub-set.

38. The method of claim 33, further comprising:if the sub-set does not include the syntax element, determining whether the sub-set includes a separate syntax element that indicates that a last non-zero coefficient is included in the sub-set; and decoding the subset if the sub-set includes the separate syntax element that indicates that a last non-zero coefficient is included in the sub-set.

39. A device configured to decode a unit of video data, comprising:a processor configured to:divide a transform block of video data into a plurality of transform coefficient sub-sets;determine, for a sub-set of the plurality of transform coefficient sub-sets, whether the sub-set includes an associated syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and determine, based on the syntax clement, whether or not to decode the sub-set.

40. The device of claim 39, wherein the processor is further configured to: if the sub-set does not include the syntax element, decode the sub-set.

41. The device of claim 40, wherein the processor is further configured to: if the sub-set of data does include the syntax element, determine whether to decode the sub-set based on the indication.

42. The device of claim 41, wherein the processor is further configured to:if the syntax clement associated with the sub-set has a first value, decode the sub-set; and if the syntax element has a second value different than the first value, not decode the sub-set.

43. The device of claim 39, wherein the processor is further configured to:determine, for each sub-set of the plurality of transform coefficient sub-sets, whether the sub-set includes an associated syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and determine, based on the syntax element, whether or not to decode the sub-set,

44. The device of claim 39, wherein the processor is further configured to:if the sub-set does not include the syntax element, determine whether the sub-set includes a separate syntax element that indicates that a last non-zero coefficient is included in the sub-set; and decode the subset if the sub-set includes the separate syntax element that indicates that a last non-zero coefficient is included in the sub-set.

45. A computer-readable storage medium that stores instructions that, when executed, cause a computing device to:divide a transform block of video data into a plurality of transform coefficient sub-sets;determine, for a sub-set of the plurality of transform coefficient sUb-sets, whether the sub-set includes an associated syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and determine, based on the syntax element, whether or not to decode the sub-set.

46. The computer-readable storage medium of claim 45, wherein the instructions further cause the computing device to:if the sub-set does not include the syntax element, decode the sub-set.

47. The computer-readable storage medium of claim 46, wherein the instructions further cause the computing device to;if the sub-set of data does include the syntax element, determine whether to decode the sub-set based on the indication.

48. The computer-readable storage medium of claim 47, wherein the instructions further cause the computing device to:if the syntax element associated with the sub-set has a first value, decode the sub-set; and if the syntax clement has a second value different than the first value, not decode the sub-set.

49. The computer-readable storage medium of claim 46, wherein the instructions further cause the computing device to:determine, for each sub-set of the plurality of transform coefficient sub-sets, whether the sub-set includes an associated syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and determine, based on the syntax element, whether or not to decode the sub-set.

50. The computer-readable storage medium of claim 45, wherein the instructions further cause the computing device to:if the sub-set does not include the syntax element, determine whether the sub-set includes a separate syntax element that indicates that a last non-zero coefficient is included in the sub-set; and decode the subset if the sub-set includes the separate syntax element that indicates that a last non-zero coefficient is included in the sub-set

51. A device configured to decode a unit of video data, comprising:means for dividing a transform block of video data into a plurality of transform coefficient sub-sets;means for determining, for a sub-set of the plurality of transform coefficient sub-sets, whether the sub-set includes a syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and means for determining, based on the syntax element, whether or not to decode the sub-set

52. The device of claim 51, further comprising:means for, if the sub-set does not include the syntax element, decoding the sub-set.

53. The device of claim 52, further comprising:means for, if the sub-set of data does include the syntax element, determining whether to decode the sub-set based on the indication.

54. The device of claim 53, further comprising:means for, if the syntax element associated with the sub-set has a first value, decoding the sub-set; and means for, if the syntax element has a second value different than the first value, not decoding the sub-set.

55. The device of claim 51, further comprising:means for determining, for each sub-set of the plurality of transform coefficient sub-sets, whether the sub-set includes an associated syntax element that indicates whether or not the sub-set includes any non-zero coefficients; and means for determining, based on the syntax element, whether or not to decode the sub-set.

56. The device of claim 51, further comprising:if the sub-set does not include the syntax element, means for determining whether the sub-set includes a separate syntax element that indicates that a last non-zero coefficient is included in the sub-set; and means for decoding the subset if the sub-set includes the separate syntax element that indicates that a last non-zero coefficient is included in the sub-set.']

211 The computer-readable storage medium of claim 17, wherein the instructions further cause the computing device to:determine whether or not to generate the syntax element based on comparing a number of potential non-zero coefficient of the sub-set to at least one threshold; and if the number of potential non-zero coefficients of the sub-set is greater than the threshold, generate the syntax element.