Block-based spatial activity measures for pictures
An encoder includes circuitry configured to receive a video frame, partition the video frame into a plurality of blocks, determine a respective spatial activity measure for each block in the plurality of blocks and using a transform matrix, encode the video frame using the spatial activity measure. Related apparatus, systems, techniques and articles are also described.
1. An inverse quantizer and inverse transform processor, the processor configured to:
receive a video signal generated from a picture, the picture having been processed at an encoder by:
segmenting the picture into a plurality of blocks;
obtaining a residual for each block of the plurality of blocks using a predictor;
applying a transform to each residual to obtain a transformed block;
determining a spatial activity for each transformed block; and
determining if each block of the plurality of blocks is assigned to a first area of the picture or a second area of the picture by determining if a difference between the spatial activity of the block and the spatial activity of a neighboring block is larger or smaller than a threshold, the blocks in the first area having been assigned by the encoder a first quantization parameter, the blocks in the second area having been assigned by the encoder a second quantization parameter;
inverse quantize the blocks of the first area using the first quantization parameter; and
inverse quantize the blocks of the second area using the second quantization parameter.
2. The processor of claim 1 , further configured to:
inverse transform the inverse quantized blocks of the first area, and
inverse transform the inverse quantized blocks of the second area.
3. The processor of claim 1 , wherein the transform is a Discrete Cosine Transform.
4. The processor of claim 2 , further comprising:
an in-loop filter; and
a decoded picture buffer.
5. The processor of claim 1 , wherein each block of the plurality of blocks is 128×128.
6. A method, the method comprising:
receiving, using an inverse quantizer and inverse transform processor, a video signal generated from a picture, the picture having been processed at an encoder by:
segmenting the picture into a plurality of blocks;
obtaining a residual for each block of the plurality of blocks using a predictor;
applying a transform to each residual to obtain a transformed block;
determining a spatial activity for each transformed block; and
determining if each block of the plurality of blocks is assigned to a first area of the picture or a second area of the picture by determining if a difference between the spatial activity of the block and the spatial activity of a neighboring block is larger or smaller than a threshold, the blocks in the first area having been assigned by the encoder a first quantization parameter, the blocks in the second area having been assigned by the encoder a second quantization parameter;
inverse quantizing, using the inverse quantizer and inverse transform processor, the blocks of the first area using the first quantization parameter; and
inverse quantizing, using the inverse quantizer and inverse transform processor, the blocks of the second area using the second quantization parameter.
7. The method of claim 6 , further comprising:
inverse transforming, using the inverse quantizer and inverse transform processor, the inverse quantized blocks of the first area, and
inverse transforming, using the inverse quantizer and inverse transform processor, the inverse quantized blocks of the second area.
8. The method of claim 6 , wherein the transform is a Discrete Cosine Transform.
9. The method of claim 7 , wherein the inverse quantizer and inverse transform processor comprises an in-loop filter and a decoded picture buffer.
10. The method of claim 6 , wherein each block of the plurality of blocks is 128×128.