Video coding

Abstract

A method of encoding a video signal representing a sequence of pictures, the method comprising comparing a first picture with a second picture, calculating a measure of the similarity between the first and the second pictures, comparing the measure of similarity with a predetermined criterion of similarity and, when the measure of similarity does not meet the predetermined criterion of similarity, outputting an indicator indicating that a non-temporally predictive error concealment method should be used by a subsequent decoder and, when the measure of similarity meets the predetermined criterion of similarity, outputting an indicator indicating that a temporally predictive error concealment method should be used by a subsequent decoder.

1 . A method of encoding a video signal representing a sequence of pictures to form an encoded video signal, the method comprising:
 generating an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and   providing the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture.   
   
   
       2 . A method according to  claim 1 , comprising generating the error concealment algorithm type indicator to indicate either a temporally-predictive or a non-temporally-predictive type of error concealment algorithm. 
   
   
       3 . A method according to  claim 1 , comprising generating the error concealment algorithm type indicator by:
 comparing a first picture of the sequence or a part thereof with a second picture of the sequence;   calculating a measure of similarity between the first picture or said part thereof and said second picture; and
 comparing the measure of similarity with a predetermined criterion of similarity. 
   
   
   
       4 . A method according to  claim 2 , comprising generating the error concealment algorithm type indicator by:
 comparing a first picture of the sequence or a part thereof with a second picture of the sequence;   calculating a measure of similarity between the first picture or said part thereof and said second picture; and   comparing the measure of similarity with a predetermined criterion of similarity.   
   
   
       5 . A method according to  claim 4 , comprising:
 generating the error concealment algorithm type indicator to indicate that a non-temporally-predictive error concealment algorithm should be used in the corresponding decoding process for the first picture or said part thereof, when the measure of similarity does not meet the predetermined criterion of similarity; and,   generating the error concealment algorithm type indicator to indicate that a temporally-predictive error concealment algorithm should be used in the corresponding decoding process for the first picture or said part thereof when the measure of similarity meets the predetermined criterion of similarity.   
   
   
       6 . A method according to  claim 5 , comprising updating the error concealment algorithm type indicator when the measure of similarity does not meet the predetermined criterion of similarity. 
   
   
       7 . A method according to  claim 5 , comprising including the error concealment algorithm type indicator in a picture header. 
   
   
       8 . A method according to  claim 5 , comprising encoding the video signal according to the H.263 standard and including the error concealment algorithm type indicator in the Supplemental Enhancement Information of the standard. 
   
   
       9 . A method according to  claim 5 , comprising updating the error concealment algorithm type indicator when the measure of similarity does not meet the predetermined criterion of similarity, and leaving the error concealment algorithm type indicator unchanged when the measure of similarity meets the predetermined criterion of similarity. 
   
   
       10 . A method according to  claim 5 , comprising using a scene identifier as the error concealment algorithm type indicator, the scene identifier having the same value for all pictures of a scene, the scene identifier having a different value for each different scene. 
   
   
       11 . A method according to  claim 5 , comprising using a scene identifier as the error concealment algorithm type indicator, the scene identifier having one of two values, with pictures from adjacent scenes having non-identical scene identifier values. 
   
   
       12 . A method according to  claim 5 , comprising including the error concealment algorithm type indicator in a picture segment header and/or a macroblock header. 
   
   
       13 . A method according to  claim 5 , comprising generating the error concealment algorithm type indicator to indicate a type of error concealment algorithm to be applied to a specified rectangular area of a picture. 
   
   
       14 . A method according to  claim 13 , comprising generating multiple error concealment algorithm type indicators for a picture, each error concealment algorithm type indicator being specific to one of a plurality of non-overlapping rectangular areas of the picture. 
   
   
       15 . An apparatus for encoding a video signal representing a sequence of pictures to form an encoded video signal, the apparatus being configured to:
 generate an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and   provide the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture.   
   
   
       16 . An apparatus according to  claim 15 , wherein the apparatus is configured to generate the error concealment algorithm type indicator to indicate either a temporally-predictive or a non-temporally-predictive type of error concealment algorithm. 
   
   
       17 . An apparatus according to  claim 28 , wherein the apparatus is configured to generate the error concealment algorithm type indicator by:
 comparing a first picture of the sequence or a part thereof with a second picture of the sequence;   calculating a measure of similarity between the first picture or said part thereof and said second picture; and
 comparing the measure of similarity with a predetermined criterion of similarity. 
   
   
   
       18 . An apparatus according to  claim 16 , wherein the apparatus is configured to generate the error concealment algorithm type indicator by:
 comparing a first picture of the sequence or a part thereof with a second picture of the sequence;   calculating a measure of similarity between the first picture or said part thereof and said second picture; and
 comparing the measure of similarity with a predetermined criterion of similarity. 
   
   
   
       19 . An apparatus according to  claim 18 , wherein the apparatus is configured to:
 generate the error concealment algorithm type indicator to indicate that a non-temporally-predictive error concealment algorithm should be used in the corresponding decoding process for the first picture or said part thereof when the measure of similarity does not meet the predetermined criterion of similarity; and   generate the error concealment algorithm type indicator to indicate that a temporally-predictive error concealment algorithm should be used in the corresponding decoding process for the first picture or said part thereof when the measure of similarity meets the predetermined criterion of similarity.   
   
   
       20 . An apparatus according to  claim 19 , wherein the apparatus is configured to update the error concealment algorithm type indicator when the measure of similarity does not meet the predetermined criterion of similarity. 
   
   
       21 . An apparatus according to  claim 19 , wherein the apparatus is configured to include the error concealment algorithm type indicator in a picture header. 
   
   
       22 . An apparatus according to  claim 19 , wherein the apparatus is configured to encode the video signal according to the H.263 standard and to include the error concealment algorithm type indicator in the Supplemental Enhancement Information of the standard. 
   
   
       23 . An apparatus according to  claim 19 , wherein the apparatus is configured to use a scene identifier as the error concealment algorithm type indicator, the scene identifier having the same value for all pictures of a scene, the scene identifier having a different value for each different scene. 
   
   
       24 . An apparatus according to  claim 19 , wherein the apparatus is configured to use a scene identifier as the error concealment algorithm type indicator, the scene identifier having one of two values, with pictures from adjacent scenes having non-identical scene identifier values. 
   
   
       25 . An apparatus according to  claim 19 , wherein the apparatus is configured to include the error concealment algorithm type indicator in a picture segment header and/or a macroblock header. 
   
   
       26 . An apparatus according to  claim 19 , wherein the apparatus is configured to generate the error concealment algorithm type indicator to indicate a type of error concealment algorithm to be applied to a specified rectangular area of a picture. 
   
   
       27 . An apparatus according to  claim 26 , wherein the apparatus is configured to provide multiple error concealment algorithm type indicators for a picture, each error concealment algorithm type indicator being specific to one of a plurality of non-overlapping rectangular areas of the picture. 
   
   
       28 . An apparatus according to  claim 19 , wherein the apparatus is configured to update the error concealment algorithm type indicator when the measure of similarity does not meet the predetermined criterion of similarity, and to leave the error concealment algorithm type indicator unchanged when the measure of similarity meets the predetermined criterion of similarity. 
   
   
       29 . A portable radio communications device including at least one of an apparatus for encoding a video signal representing a sequence of pictures to form an encoded video signal and an apparatus for decoding an encoded video signal representing a sequence of pictures, the apparatus for encoding a video signal being configured to:
 generate an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and   provide the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture, and   
     the apparatus for decoding an encoded video signal being configured to:
 receive an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator being separate from an indication of an encoding mode for the picture; 
 use the received error concealment algorithm type indicator as the basis for choosing a particular error concealment algorithm of the type indicated; and 
 apply the chosen error concealment algorithm to conceal an error in the picture or said part thereof. 
 
   
   
       30 . An apparatus for encoding a video signal representing a sequence of pictures to form an encoded video signal, the apparatus comprising one or more functional units for:
 generating an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and   providing the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture.   
   
   
       31 . An apparatus for encoding a video signal representing a sequence of pictures to form an encoded video signal, the apparatus comprising a processor configured to control:
 generation of an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator for providing an indication of a type of error concealment algorithm, said indication to be used as the basis for choosing, in a corresponding decoding process, a particular error concealment algorithm of the type indicated; and   provision of the error concealment algorithm type indicator, for use in the corresponding decoding process, separate from an indication of an encoding mode for the picture.   
   
   
       32 . An apparatus for decoding an encoded video signal representing a sequence of pictures, the apparatus comprising a processor configured to control:
 reception of an error concealment algorithm type indicator for a picture or a part thereof, the error concealment algorithm type indicator being separate from an indication of an encoding mode for the picture;   choice of a particular error concealment algorithm of a type indicated by the received error concealment algorithm type indicator; and   application of the chosen error concealment algorithm to conceal an error in the picture or said part thereof.