Applying a scaling factor to select a filter for filtering decoded video data

1 . A method of filtering decoded video data, the method comprising:

calculating a first filter selection value for a first color component of a decoded block of video data;

determining a first scaling factor for the first filter selection value for the first color component of the decoded block;

quantizing the first filter selection value using the first scaling factor to form a first quantized filter selection value;

selecting a first filter for the first color component of the decoded block according to the first quantized filter selection value as a first selected filter;

filtering the first color component of the decoded block using the first selected filter;

calculating a second filter selection value for a second color component of the decoded block, the second color component being different than the first color component;

determining a second scaling factor based on the second color component;

quantizing the second filter selection value using the second scaling factor to form a second quantized filter selection value;

selecting a second filter for the second color component according to the second quantized filter selection value; and

filtering the second color component using the second filter.

2 . The method of claim 1 , wherein the first filter selection value comprises an activity value, and wherein calculating the activity value for the decoded block comprises:

calculating one or more gradient values; and

determining the activity value according to whether a sum of the gradient values exceeds a threshold.

3 . The method of claim 2 , wherein the one or more gradient values include a horizontal gradient value (g h ) and a vertical gradient value (g v ), and wherein determining the activity value comprises comparing g h to a first threshold and comparing g v to a second threshold.

4 . The method of claim 1 , wherein the first filter selection value comprises an activity value, and wherein calculating the activity value comprises calculating a sum of a horizontal Laplacian value and a vertical Laplacian value.

5 . The method of claim 1 , wherein the first filter selection value comprises a variance value.

6 . The method of claim 5 , wherein calculating the variance value comprises calculating one of a standard deviation, a variance, a mean, or a median of a window of samples, the window of samples including at least part of the decoded block.

7 . The method of claim 6 , wherein calculating the variance value further comprises calculating differences between samples of the decoded block and the calculated one of the standard deviation, the variance, the mean, or the median of the window.

8 . The method of claim 7 , wherein calculating the variance value comprises calculating one of sum of absolute differences (SAD) of the differences, sum of squared differences (SSD) of the differences, or a square root of the sum of squared values of the differences.

9 . The method of claim 1 , wherein the first color component comprises one of luminance, blue hue chrominance, or red hue chrominance.

10 . The method of claim 1 , wherein determining the first scaling factor further comprises determining the first scaling factor the decoded block, the color information comprising a a color sampling format for the decoded block or a picture including the decoded block.

11 . The method of claim 10 , wherein the color sampling format comprises one of 4:2:0, 4:2:2, or 4:4:4.

12 . The method of claim 1 , wherein selecting the first filter comprises determining a class for the decoded block according to the first quantized filter selection value.

13 . The method of claim 1 , further comprising encoding the decoded block prior to decoding the decoded block.

14 . A device for filtering decoded video data, the device comprising:

a memory configured to store video data; and

a processing system implemented in circuitry and configured to:

calculate a first filter selection value for a first color component of a decoded block of video data;

determine a first scaling factor for the first filter selection value for the first color component for the decoded block;

quantize the first filter selection value using the first scaling factor to form a first quantized filter selection value;

select a first filter for the first color component of the decoded block according to the first quantized filter selection value as a first selected filter;

filter the first color component of the decoded block using the first selected filter;

calculate a second filter selection value for a second color component of the decoded block, the second color component being different than the first color component;

determine a second scaling factor based on the second color component;

quantize the second filter selection value using the second scaling factor to form a second quantized filter selection value;

select a second filter for the second color component according to the second quantized filter selection value; and

filter the second color component using the second filter.

15 . The device of claim 14 , further comprising a display configured to display a picture that includes the decoded block of video data.

16 . The device of claim 14 , wherein the device comprises one or more of a camera, a computer, a mobile device, a broadcast receiver device, or a set-top box.

17 . The device of claim 14 , further comprising a memory configured to store the video data.

18 . The device of claim 14 , wherein the first filter selection value comprises an activity value, and wherein to calculate the activity value, the processing system is configured to calculate a sum of a horizontal Laplacian value and a vertical Laplacian value.

19 . A device for filtering decoded video data, the device comprising:

means for calculating a first filter selection value for a first color component of a decoded block of video data;

means for determining a first scaling factor for the first filter selection value for the first color component of the decoded block;

means for quantizing the first filter selection value using the first scaling factor to form a first quantized filter selection value;

means for selecting a first filter for the decoded block according to the first quantized filter selection value;

means for filtering the first color component of the decoded block using the first selected filter;

means for calculating a second filter selection value for a second color component of the decoded block, the second color component being different than the first color component;

means for determining a second scaling factor based on the second color component;

means for quantizing the second filter selection value using the second scaling factor to form a second quantized filter selection value;

means for selecting a second filter for the second color component according to the second quantized filter selection value; and

means for filtering the second color component using the second filter.

20 . The device of claim 19 , wherein the first filter selection value comprises an activity value, and wherein the means for calculating the activity value comprises means for calculating a sum of a horizontal Laplacian value and a vertical Laplacian value.