Spatial scalable compression

A layered encoder for encoding and decoding a video stream, comprising:

• a downsampling unit for reducing the resolution of the video stream;
• a base encoder for encoding a lower resolution base stream;
• an upconverting unit for decoding and increasing the resolution of the base stream to produce a reconstructed video stream;
• a subtractor unit for subtracting the reconstructed video stream from the original video stream to produce a residual signal;
• a picture analyzer for performing segmentation and determining which groups of pixels in each frame have at least a predetermined chance of having a predetermined characteristic and calculating a gain value for the content of each pixel, wherein the gain for pixels which have the at least predetermined chance of having the predetermined characteristic is biased toward 1 and the gain for other pixels is biased toward 0;
• a first multiplier unit which multiplies the residual signal by the gain values so as to remove bits from the residual signal which do not have the predetermined chance of having the predetermined characteristic;
• an enhancement encoder for encoding the resulting residual signal from the multiplier and outputting an enhancement stream.

A method for providing spatial scalable compression using adaptive content filtering of a video stream, comprising the steps of:

• downsampling the video stream to reduce the resolution of the video stream;
• encoding the downsampled video stream to produce a base stream;
• decoding and upconverting the base stream to produce a reconstructed video stream;
• subtracting the reconstructed video stream from the video stream to produce a residual stream;
• determining which segments or pixels in each frame have at least a predetermined chance of having a predetermined characteristic;
• calculating a gain value for the content of each segment or pixel, wherein the gain for pixels which have the at least predetermined chance of having the predetermined characteristic is biased toward 1 and the gain for other pixels is biased toward 0;
• multiplying the residual stream by the gain values so as to remove bits from the residual stream which do not have the predetermined chance of having the predetermined characteristic;
• and
• encoding the resulting residual stream and outputting an enhancement stream.