Video encoding and decoding
A method for encoding video with a two-dimensional (2D) transform separable to two one-dimensional (1D) transforms. The method receives an array of values for a sub-section of an image, performs a first 1D-transform of the array, transposes the resulting array, and performs a second 1D-transform of the array resulting from the transpose. The method, without performing another transpose, generates a data stream using a transposed scan order based on the values of the array resulting from the second transform. A method for decoding video encoded by a 2D transform, which separable to two 1D transforms. The method receives a data stream containing encoded values for an image, parses out the values into an array using a transposed scan order, performs a first 1D-inverse transform on the array, transposes the resulting array, and performs a second 1D-inverse transform of the array resulting from the transpose to produce a decoded output.
1. A method of dynamically transposing an image-value array associated with a video image, the method comprising:
a) identifying a pattern of coefficients of the image-value array;
b) determining whether a particular set of transpose operations exists for the identified pattern of coefficients;
c) when the particular set of transpose operations exists for the identified pattern, using the particular set of transpose operations to transpose the image-value array; and
d) when the particular set of transpose operations does not exist for the identified pattern, using a default set of transpose operations to transpose the image-value array.
2. The method of claim 1 wherein the pattern of coefficients is a pattern of non-zero coefficients.
3. The method of claim 1 wherein the image-value array includes encoded image values.
4. The method of claim 1 wherein the image-value array includes unencoded image values.
5. The method of claim 1 wherein detennining whether a particular set of transpose operations exists comprises a table look up operation.
6. The method of claim 5 , wherein the table stores different patterns of non-zero coefficients and a set of corresponding transpose operations for each stored pattern.
7. A computer readable medium storing a computer program for dynamically transposing an image-value array associated with a video image, the computer program comprising sets of instructions for:
a) identiPying a pattern of coefficients of the image-value array;
b) detennining whether a particular set of transpose operations exists for the identified pattern of coefficients;
c) when the particular set of transpose operations exists for the identified pattern, using the particular set of transpose operations to transpose the image-value array; and
d) when the particular set of transpose operations does not exist for the identified pattern, using a default set of transpose operations to transpose the image-value array.
8. The computer readable medium of claim 7 , wherein the pattern of coefficients is a pattern of non-zero coefficients.
9. The computer readable medium of claim 7 , wherein the image-value array includes encoded image values.
10. The computer readable medium of claim 7 , wherein the image-value array includes unencoded image values.
11. The computer readable medium of claim 7 , wherein determining whether a particular set of transpose operations exists comprises a table look up operation.
12. The computer readable medium of claim 11 , wherein the table stores different patterns of non-zero coefficients and a set of corresponding transpose operations for each stored pattern.