Method and apparatus to process video sequences in transform space

Abstract

A system configured to preform pre-compression on video sequences within a transform space to improve the compressibility of the video sequence during standard video encoding. In some cases, the pre-compression is configured to prevent the introduction of perceivable distortion into the video sequence or to substantially minimize the introduction of perceivable distortion. In some examples, a transform-Domain video processor may pre-compress or pre-process the video sequence in one, two, or three dimensional blocks or sequences using models of human visual contrast sensitivity.

What is claimed is: 
     
         1 . A method comprising:
 receiving a set of frames;   transforming the set of frames into a linearly equivalent transform representation of the set of frames;   determining transform components associated with a dimensional transform based at least in part on blocks of the visual data associated with the set of frames, each of the blocks having a specified transformation block size;   determining a specified angular size and a resolution of visually quantizers by applying a spatial contrast sensitivity function to frequencies of the transform components;   quantizing the set of frames using the visually quantizers to generate pre-compressed representation of the set of frames; and   performing an inverse transform operation on the pre-compressed representation of the set of frames to construct a pre-compressed set of frames, the pre-compressed set of frames compressible, by a video encoder, to a smaller size than the set of frames.   
     
     
         2 . The method as recited in  claim 1 , wherein the dimensional transform and the inverse transform operation are in the linearly equivalent transform space. 
     
     
         3 . The method as recited in  claim 1 , wherein the visually quantizers are determined at least in part based on an inverse of an amplitude of an unevenly-spaced transform domain component frequency. 
     
     
         4 . The method as recited in  claim 1 , wherein the dimensional transform is an unevenly-spaced frequency transform. 
     
     
         5 . The method as recited in  claim 1 , wherein the dimensional transform is an evenly-spaced frequency transform. 
     
     
         6 . The method as recited in  claim 1 , wherein the set of frames are part of a video sequence. 
     
     
         7 . The method as recited in  claim 1 , wherein the dimensional transform is a two-dimensional transform. 
     
     
         8 . A method comprising:
 receiving a set of frames;   generating a series of adjacent pixels from the set of frames;   generating a frequency domain representation of the series of pixels by applying a reversible linear forward transform to the series of adjacent pixels;   applying a frequency response shape function to the frequency domain representation of the series of pixels; and   performing an inverse transform operation on the frequency domain representation of the series of pixels to in part construct a pre-compressed set of frames, the pre-compressed set of frames compressible, by a video encoder, to a smaller size than the set of frames.   
     
     
         9 . The method as recited in  claim 8 , wherein applying the frequency response shape function to the frequency domain representation of the series of pixels includes applying a multiplicative constant to individual frequency amplitudes of the frequency domain representation of the series of pixels. 
     
     
         10 . The method as recited in  claim 8 , wherein applying the frequency response shape function to the frequency domain representation of the series of pixels includes applying a quantize operation followed by a dequantize operation using a quantizing factor determined for each individual frequency of the frequency domain representation of the series of pixels. 
     
     
         11 . The method as recited in  claim 8 , further comprising:
 generating a second series of adjacent pixels from the set of frames;   
       generating, substantially concurrently with the first frequency domain representation of the first series of pixels, a second frequency domain representation of the second series of pixels by applying the reversible linear forward transform to the second series of adjacent pixels;
 applying, substantially concurrently with applying the frequency response shape function to the first frequency domain representation of the first series of pixels, the frequency response shape function to the second frequency domain representation of the second series of pixels; and 
 performing, substantially concurrently with performing the inverse transform operation on the first frequency domain representation of the first series of pixels, a second inverse transform operation on the second frequency domain representation of the second series of pixels to in part construct the pre-compressed set of frames. 
 
     
     
         12 . A method comprising:
 receiving a plurality of three-dimensional (3D) input block associated with a set of frames, each of the plurality of 3D input blocks having a specified transformation block size;   generate a frequency domain representation of the plurality of 3D input blocks by applying a reversible linear forward transform to the plurality of 3D input blocks;   apply a frequency response shape function to the frequency domain representation of the plurality of 3D input blocks; and   performing an inverse transform operation on the frequency domain representation of the plurality of 3D input blocks to in part construct a pre-compressed set of frames.   
     
     
         13 . The method as recited in  claim 12 , further comprising receiving the reversible linear forward transform and storing the reversible linear forward transform prior to generating the frequency domain representation of the plurality of 3D input blocks. 
     
     
         14 . The method as recited in  claim 12 , further comprising selecting the reversible linear forward transform based at least in part on the set of frames prior to generating the frequency domain representation of the plurality of 3D input blocks. 
     
     
         15 . The method as recited in  claim 12 , wherein the reversible linear forward transform is a reversible 3D linear forward transform. 
     
     
         16 . The method as recited in  claim 12 , wherein applying the frequency response shape function to the frequency domain representation of the plurality of 3D input blocks includes applying a multiplicative constant to individual frequency amplitudes of the frequency domain representation of the plurality of 3D input blocks. 
     
     
         17 . The method as recited in  claim 12 , wherein applying the frequency response shape function to the frequency domain representation of the plurality of 3D input blocks includes applying a quantize operation followed by a dequantize operation using a quantizing factor determined for each individual frequency of the frequency domain representation of the plurality of 3D input blocks. 
     
     
         18 . The method as recited in  claim 12 , further comprising:
 encoding the pre-compressed set of frames into an encoded set of frames; and   sending the encoded set of frames to a remote device.   
     
     
         19 . The method as recited in  claim 12 , further comprising:
 compressing the pre-compressed set of frames into a compressed set of frames, the compressed set of frames having a smaller size than a compressed version of the set of frames.   
     
     
         20 . The method as recited in  claim 12 , further comprising:
 receiving a second plurality of 3D input block associated with the set of frames;   generating, substantially concurrently with the first frequency domain representation of the first plurality of 3D input block, a second frequency domain representation of the second plurality of 3D input block by applying the reversible linear forward transform to the second plurality of 3D input block;   applying, substantially concurrently with applying the frequency response shape function to the first frequency domain representation of the first plurality of 3D input block, the frequency response shape function to the second frequency domain representation of the second plurality of 3D input block; and   performing, substantially concurrently with performing the inverse transform operation on the first frequency domain representation of the first plurality of 3D input block, a second inverse transform operation on the second frequency domain representation of the second plurality of 3D input block to in part construct the pre-compressed set of frames.