Variable number of intra modes for video coding

1. A method for coding video data, the method comprising:

determining a first block of the video data is intra mode coded, wherein the first block of the video data has a first height and a first width;

based on the first height and the first width corresponding to the first block having an area greater than a threshold value, identifying a group of N available intra prediction modes for the first block of video data, wherein N is an integer value greater than two;

selecting from the group of N available intra prediction modes, a first intra prediction mode used to code the first block of the video data;

coding the first block using the first intra prediction mode;

determining a second block of the video data is intra mode coded, wherein the second block of the video data has a second height and a second width;

based on the second height and the second width corresponding to the second block having an area less than the threshold value, identifying a group of M available intra prediction modes for the second block of video data, wherein M is a smaller integer value than N and is greater than two; and

selecting from the group of M available intra prediction modes, a second intra prediction mode used to code the second block of the video data.

2. The method of claim 1 , further comprising:

signaling the threshold value in the video data.

3. The method of claim 1 , wherein each intra prediction mode in the group of N available intra prediction modes has a unique index ranging from 0 to N-1, and wherein each intra prediction mode in the group of M available intra prediction modes has a unique index ranging from 0 to M-1.

4. The method of claim 1 , wherein the first height is greater than the first width, the method further comprising:

determining a second block of the video data is intra mode coded, wherein the second block of the video data has a second height and a second width, and wherein the second width is greater than the second height;

based on the second height and the second width, identifying a group of M available intra prediction modes for the second block of video data, wherein the group of M available intra prediction modes includes at least one intra prediction mode not included in the group of N available intra prediction modes; and

selecting from the group of M available intra prediction modes, a second intra prediction mode used to code the second block of the video data.

5. The method of claim 1 , wherein coding the first block using the first intra prediction mode comprises one of:

encoding the first block using the first intra prediction mode; or

decoding the first block using the first intra prediction mode.

6. A device for coding video data, the device comprising:

a memory configured to store the video data; and

one or more processors configured to:

determine a first block of the video data is intra mode coded, wherein the first block of the video data has a first height and a first width;

based on the first height and the first width corresponding to the first block having an area greater than a threshold value, identify a group of N available intra prediction modes for the first block of video data, wherein N is an integer value greater than two;

select from the group of N available intra prediction modes, a first intra prediction mode used to code the first block of the video data;

code the first block using the first intra prediction mode;

determine a second block of the video data is intra mode coded, wherein the second block of the video data has a second height and a second width;

based on the second height and the second width corresponding to the second block having an area less than the threshold value, identify a group of M available intra prediction modes for the second block of video data, wherein M is a smaller integer value than N and is greater than two; and

select from the group of M available intra prediction modes, a second intra prediction mode used to code the second block of the video data.

7. The device of claim 6 , wherein the one or more processors are further configured to:

signal the threshold value in the video data.

8. The device of claim 6 , wherein each intra prediction mode in the group of N available intra prediction modes has a unique index ranging from 0 to N-1, and wherein each intra prediction mode in the group of M available intra prediction modes has a unique index ranging from 0 to M-1.

9. The device of claim 6 , wherein the first height is greater than the first width, wherein the one or more processors are further configured to:

determine a second block of the video data is intra mode coded, wherein the second block of the video data has a second height and a second width, and wherein the second width is greater than the second height;

based on the second height and the second width, identify a group of M available intra prediction modes for the second block of the video data, wherein the group of M available intra prediction modes includes at least one intra prediction mode not included in the group of N available intra prediction modes; and

select from the group of M available intra prediction modes, a second intra prediction mode used to code the second block of the video data.

10. The device of claim 6 , wherein to code the first block using the first intra prediction mode, the one or more processors are further configured to at least one of:

encode the first block using the first intra prediction mode; or

decode the first block using the first intra prediction mode.

11. The device of claim 6 , wherein the device comprises a wireless communication device configured to decode the video data, further comprising a receiver configured to receive encoded video data.

12. The device of claim 11 , wherein the wireless communication device comprises a telephone handset and wherein the receiver is configured to demodulate, according to a wireless communication standard, a signal comprising the encoded video data.

13. The method of claim 1 , wherein coding comprises decoding, the method further comprising:

receiving the video data at a receiver of a wireless communication device;

storing the video data in a memory of the wireless communication device; and

processing the video data on one or more processors of the wireless communication device.

14. The method of claim 13 , wherein the wireless communication device comprises a telephone handset and wherein receiving the video data at the receiver of the wireless communication device comprises demodulating, according to a wireless communication standard, a signal comprising the video data.

15. The method of claim 1 wherein coding comprises encoding, the method further comprising:

storing the video data in a memory of a wireless communication device;

processing the video data on one or more processors of the wireless communication device; and

transmitting the video data from a transmitter of the wireless communication device.

16. The method of claim 15 , wherein the wireless communication device comprises a telephone handset and wherein transmitting the video data at the transmitter of the wireless communication device comprises modulating, according to a wireless communication standard, a signal comprising the video data.

17. The device of claim 6 , wherein the device comprises a wireless communication device configured to encode the video data, the device further comprising a transmitter configured to transmit encoded video data.

18. The device of claim 17 , wherein the wireless communication device comprises a telephone handset and wherein the transmitter is configured to modulate, according to a wireless communication standard, a signal comprising the encoded video data.

19. A non-transitory computer-readable storage medium storing instructions that when executed by one or more processors cause the one or more processors to:

determine a first block of the video data is intra mode coded, wherein the first block of the video data has a first height and a first width;

based on the first height and the first width corresponding to the first block having an area greater than a threshold value, identify a group of N available intra prediction modes for the first block of video data, wherein N is an integer value greater than two;

select from the group of N available intra prediction modes, a first intra prediction mode used to code the first block of the video data;

code the first block using the first intra prediction mode;

determine a second block of the video data is intra mode coded, wherein the second block of the video data has a second height and a second width;

based on the second height and the second width corresponding to the second block having an area less than the threshold value, identify a group of M available intra prediction modes for the second block of video data, wherein M is a smaller integer value than N and is greater than two; and

select from the group of M available intra prediction modes, a second intra prediction mode used to code the second block of the video data.

20. The non-transitory computer-readable storage medium of claim 19 , storing further instructions that when executed cause the one or more processors to:

signal the threshold value in the video data.

21. The non-transitory computer-readable storage medium of claim 19 , wherein each intra prediction mode in the group of N available intra prediction modes has a unique index ranging from 0 to N-1, and wherein each intra prediction mode in the group of M available intra prediction modes has a unique index ranging from 0 to M-1.

22. The non-transitory computer-readable storage medium of claim 19 , wherein the first height is greater than the first width, and storing further instructions that when executed cause the one or more processors to:

determine a second block of the video data is intra mode coded, wherein the second block of the video data has a second height and a second width, and wherein the second width is greater than the second height;

based on the second height and the second width, identify a group of M available intra prediction modes for the second block of the video data, wherein the group of M available intra prediction modes includes at least one intra prediction mode not included in the group of N available intra prediction modes; and

select from the group of M available intra prediction modes, a second intra prediction mode used to code the second block of the video data.

23. The non-transitory computer-readable storage medium of claim 19 , storing further instructions that when executed cause the one or more processors to:

determine an area of the first block based on the first height and the first width; and

based on the area, determine a value for N.

24. The non-transitory computer-readable storage medium of claim 19 , storing further instructions that when executed cause the one or more processors to code the first block using the first intra prediction mode by at least one of:

encoding the first block using the first intra prediction mode; or

decoding the first block using the first intra prediction mode.