Methods and apparatus for reducing blockiness in decoded video

DETAILED DESCRIPTION The present invention provides for methods and apparatus for determining and/or indicating when blockiness reduction techniques should be applied to encoded video images.
In accordance with one embodiment of the present invention, an encoder detects when the video data being encoded will result in blocky video images.
The encoder incorporates information identifying the encoded data that will result in blocky video images into the encoded video bitstream generated by the encoder.
In addition, the encoder may include in the encoded video bitstream instructions for processing the blocky video data to reduce the blockiness of the images generated from the encoded video data.
The information identifying the blocky video data and specific instructions for processing such blocky video data may be included in, e.
g.
, MPEG transport headers.
In another embodiment of the present invention, a decoder incorporates a circuit for detecting encoded video data that will produce blocky video images.
The blockiness identification circuit does this by monitoring a received encoded video bitstream for one or more indica of blocky video data.
One of these is the information identifying data corresponding to blocky images that is generated by the encoder of the present invention.
Other indica which may be used to detect encoded video data corresponding to blocky video images include high quantization scale factors, large numbers of intra coded macroblocks in predictively coded and/or bi-directionally coded video frames, large motion vectors and/or a cost function which is determined using pixel differences at block boundaries.
The video encoder of the present invention may use the same or similar indica of blocky video images to identify encoded data generated by the encoder that will result in blocky video images.
In accordance with the present invention video data that is identified as likely to produce blocky images is processed, e.
g.
, by using a Gaussian low pass filter, by filtering at just the block boundaries or by adjusting IDCT coefficients to minimize a blockiness cost function used to estimate the impact blockiness will have on the quality of the image which will be generated from the blocky video data