Methods and apparatus for reducing the cost of video decoders

A method of processing and displaying video data, including data representing a bi-directionally coded image and an intra-coded image, the method comprising the steps of:

• storing data representing the intra-coded image;
• discarding data corresponding to a portion of the bi-directionally coded image which will not be displayed;
• storing data representing a portion of the bi-directionally coded image which will be displayed;
• displaying a first image generated from the data representing the stored intra-coded image;
• and
• displaying a second image generated from the stored data representing a portion of the bi-directionally coded image.

A method of processing encoded video data, comprising the steps of:

• receiving encoded data representing at least one intra-coded image only a portion of which is to be displayed after decoding;
• decoding the encoded data representing the portion of the intra-coded image which is to be displayed after decoding at a first resolution;
• and
• decoding the encoded data representing the portion of the intra-coded image which is not to be displayed after decoding at a second resolution which is lower than the first resolution.

A method of decoding encoded image data, comprising the steps of:

• identifying a center of interest of an encoded image by examining the encoded image data for center of interest information included therein;
• decoding a first portion of the encoded image data representing a first image portion located a first distance from the identified center of interest in accordance with a first decoding procedure;
• and
• decoding a second portion of the encoded image data representing a second portion of the encoded image located a second distance from the center of interest using a second decoding procedure which is less resource intensive than the first decoding procedure, the second distance being greater than the first distance.

A method of processing encoded video data, comprising the steps of:

• receiving encoded data representing at least one predictively-coded image only a portion of which is to be displayed after decoding;
• decoding the encoded data representing the portion of the predictively-coded image which is to be displayed after decoding at a first resolution;
• and
• decoding the encoded data representing the portion of the predictively-coded image which is not to be displayed after decoding at a second resolution which is lower than the first resolution.

A video decoder apparatus, comprising:

• means for identifying and discarding encoded image data representing a portion of a B-frame which is not to be displayed;
• means for decoding encoded image data representing a portion of a bi-directionally coded frame which is to be displayed;
• and
• a memory device coupled to the means for decoding for storing decoded image data.

A video decoder apparatus, comprising:

• a circuit for identifying image data representing a portion of an intra-coded frame which is not to be displayed;
• a data reduction device for performing a data reduction operation on the data representing the portion of the intra-coded frame which is not to be displayed;
• a storage device for storing the data generated by the data reduction device;
• and
• a motion compensated prediction circuit coupled to the storage device for using the stored data to perform a motion compensated prediction operation.

A video decoder apparatus, comprising:

• a circuit for identifying image data representing a portion of a predictively-coded frame which is not to be displayed;
• a data reduction device for performing a data reduction operation on the data representing the portion of the predictively coded frame which is not to be displayed;
• a storage device for storing data generated by performing the data reduction operation;
• and
• a motion compensated prediction circuit coupled to the storage device for using stored data to perform a motion compensated perdition operation.